effects of nutritional and environmental factors on physiological responses and semen...
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EFFECTS OF NUTRITIONAL AND ENVIRONMENTAL
FACTORS ON PHYSIOLOGICAL RESPONSES AND
SEMEN CHARACTERISTICS OF DESERT RAMS
BY
SUHAIR SAYED MOHAMMED A/ ALRAHMAN (B.V.Sc., University of Cairo, M.V.Sc., University of Khartoum)
Thesis submitted in fulfillment of the requirement of the degree of
Ph.D. in Veterinary Science in Animal Physiology
Supervisor
Dr. Abdalla M. Abdelatif
(B.V.Sc , M.V.Sc., Ph.D.)
Department of Physiology
Faculty of Veterinary Medicine
University of Khartoum
November, 2005
DEDICATION
To the soul of my
dear younger brother
Ustaz Omer Sayed, whose
love, sympathy and
assistance brought this
work to the end.
fâ{t|Ü
Acknowledgements
Iam greatly indebted to my supervisor Dr. Abdalla M. Abdelatif
with sincere thanks for his continuous help and guidance and patience
throughout this study.
Iam particularly grateful to Dr. Faisal H. Ibrahim, Minister of
Agriculture, Animal Resources and Irrigation – Khartoum State and Prof.
Ali M. Abdelmagid for their financial support. Also special thanks are
due to the administration of Bahr Elghazal University for granting me
necessary time and fund to fulfil this work.
Due thanks and gratitude are to my brother Ustaz Mohammed
Sayed , whose presence by my side throughout this study helped me to
overcome all accompanied hinders and events . My thanks are
extended to Ustaz Mohamed E. Alnageeb, Ustaz Ashwag Alnour,
Hussien A. El Gadir, Staff of Department of Physiology and staff of
Department of Biochemistry–Soba Research Centre for their assistance
during the study. Special thanks are to Dr. Shawgi M. Hassan and Ustaz
Alwasila Mukhtar for their assistance in the statistical analysis, Ustaz A.
Hamed A. Rahim for typing this thesis.
Finally Iam most grateful to my family, sisters and brothers for
their endless emotional support .
ABSTRACT
The studies were conducted to investigate the effects of certain
nutritional and climatic factors on thermoregulation, blood composition
and semen characteristics of Desert rams .The experimental design
included evaluation of the effects of lowering the level of feeding
Lucerne hay to 66% (medium) and 33% (low) at libitum level on
thermoregulation, blood metabolites and semen characteristics under
typical winter and summer thermal environments. Also the effects of
exposure of Desert rams to solar radiation and exhaustion test , performed
by frequent ejaculation, on thermoregulation, blood metabolites and
semen characteristics were evaluated. The responses of rams to shearing
and fasting during winter and summer conditions were also investigated.
Feeding 33% at libitum level of lucerne hay during winter and
summer resulted in lowering of body weight (BW) and scrotal
circumference (SC) of Desert rams. The rectal temperature (Tr) decreased
significantly in the morning and afternoon and showed a diurnal pattern.
The respiration rate (RR) was significantly lowered during the morning.
Serum total protein concentration was significantly lower during winter
and serum albumin concentration was significantly lower in both seasons
in response to feed restriction. In both seasons, feed restriction
significantly lowered ejaculate volume, sperm individual motility and
sperm concentration. During summer , sperm mass motility and live
sperm percentage were significantly lower and abnormal sperm
percentage was significantly higher.
Exposure of Desert rams to solar radiation significantly increased
morning rectal temperature (Tr) in the second week and afternoon value
of (Tr) in the first week of the experimental period. The respiratory rate
(RR) in the morning and afternoon was significantly higher in the last
week of the experimental period. In the last two weeks of the
experimental period , the ratio of neutrophils was significantly lower and
that of monocytes was significantly higher. The ratio of eosinophils was
significantly lower in the last week of the experimental period compared
to the value obtained for the shaded group. Compared to the control the
unshaded rams also had significantly higher serum total protein
concentration in the third week of the experimental period, while the
concentration of serum albumin was significantly lower in the second
week of exposure to solar radiation.Serum urea and plasma glucose levels
were significantly lower in the third week of the experimental period. The
ejaculate volume, sperm mass and individual motility, sperm
concentration and live sperm percent were significantly lower in response
to solar heat stress while abnormal sperm percent was significantly
higher. The exhaustion test of the rams for 3 consecutive days during
exposure to solar radiation resulted in lower PCV level in the last day of
the experimental period and low total leukocyte count (TLC) in the first
day. The serum total protein level was significantly lower in the first and
second day, and the plasma glucose level was significantly increased in
the second day. For seminal traits, the sperm individual motility, sperm
cell concentration and abnormal sperm percent were significantly lower
in response to exhaustion test and heat stress ;while the percent of live
sperm was significantly higher. Exhaustion of shaded rams lowered PCV
level during the three days of the experimental period, total leukocytes
(TLC) in the first and second days and the percent of monocytes in the
first day. In shaded rams exhaustion test significantly lowered the
concentration of serum total protein in the first and second day of the
experimental period; while the concentration of serum urea and plasma
glucose increased in the last and first day of the experimental period
respectively. Exhaustion of shaded rams significantly lowered the
ejaculate volume in the three days, sperm individual motility in the first
and third day and sperm concentration in the first and second day of the
experimental period .The percent of abnormal sperm was significantly
higher in the second day .
Shearing of rams significantly lowered rectal temperature (Tr) in
the morning during winter and summer and in the afternoon during
summer only. The respiration rate (RR) was significantly lower in
response to shearing in the afternoon during winter and summer. The
plasma glucose level was significantly higher during winter in shorn
rams compared to summer values. The sperm mass motility was
significantly lower during summer compared to winter and the sperm
individual motility was significantly lower in both seasons in response to
shearing. Compared to respective values obtained for the control group,
fasting of shorn rams resulted in significantly lower ratio of lymphocytes
during both seasons and higher monocytes ratio during summer.
However, in both groups the ratio of neutrophils and eosinophils was
significantly higher during summer and the ratio of monocytes was
significantly lower. The serum concentrations of total protein and urea
were significantly higher in winter in shorn fasted rams compared to
values obtained for the unshorn. During summer, fasting of shorn rams
significantly lowered serum urea concentration. In both seasons, plasma
glucose concentration was significantly higher in fasted shorn rams
compared to unshorn, and it was significantly lower during winter post-
fasting in shorn rams compared to values obtained during summer.
The findings of these studies showed that feed restriction
induced significant changes in the physiological responses of Desert
rams. The results indicated that Desert rams can acclimatize on exposure
to direct solar radiation. However, thermal stress negatively affected
scrotal thermoregulatory mechanism and consequently seminal traits.
Exhaustion of unshaded rams did not exert an additional stressful
condition. Shearing of Desert rams had positive influences on
thermoregulation during both seasons and negative influences on sperm
motility.
LIST OF CONTENTS
Page
DEDICATION……………………………………………..………………………………………….. i
ACKNOWLEDGEMENTS………………………….…………………………………………… ii
ABSTRACT …………………………………………………………………………………………… iii
LIST OF CONTENTS………………………..………………..…………………………………… v
LIST OF TABLES………………………………….……………………………………………… xv
CHAPTER ONE: GENERAL INTRODUCTION ………......…………………… 1
1.1 Economic importance of sheep in
Sudan………………………………………..…… 1
1.2. Reproductive performance of sheep under tropical conditions……………… 2
1.3 Effects of nutritional factors………...……………………………………………………… 3
1.3.1. Thermoregulation………………….………………………………………………………… 3
1.3.2 Blood metabolites………………………………………………………………….………… 5
1.3.3 Semen characteristics……………..………………………………………………………… 6
1.4 Effects of thermal factors on male animals……………………………...………… 10
1.4.1 Effects of seasonal changes in thermal environment………………….……… 10
1.4.1.1 Thermoregulation…………………………………………………………….…………… 11
1.4.1.2 Blood composition……………………………………………………………..………… 12
1.4.1.3 Semen characteristics ………………………………...…………………………………
1.4.2 Effects of exposure to solar radiation……………………………………..…………
13
15
1.4.2.1 Thermoregulation………………………………………………………………………… 16
1.4.2.2 Blood composition……….………..……………………………………………………… 16
1.4.2.3 Semen characteristics………………………………………..…..……………………… 18
1.4 .3 Effects of thermal environment and shearing……….…………….…………… 19
1.4.3.1 Thermoregulation……………………….………………………………………………… 20
1.4.3.2 Blood composition………………………...……………………………………………… 21
1.4.3.3 Semen characteristics…………………………………..………………………………… 22
1.5 Effects of frequency of ejaculation………………………….…………………………… 22
1.5.1 Frequent ejaculation of semen and assessment of male reproductive
capacity …………………………………………………………………..……………………… 22
1.5.2 Effects of frequent ejaculation on semen characteristics…..………………… 23
1.6 Objectives …………………………….…………………………………………………………… 26
CHAPTER TWO: MATERIALS AND METHODS.......................................... 28
2.1 Experimental animals………………………….……………………………………………… 28
2.2 Housing and management…………………………………………………………………… 28
2.3. Rectal temperature (Tr) …………………...………………………………………………… 30
2.4 Respiration rate (RR) ………………….……………………………………………………… 30
2.5 Body weight (BW) …………………..………………………………………………………… 30
2.6 Scrotal circumference (SC) ………………………………………………………………… 30
2.7 Collection of samples………………….……………………………………………………… 30
2.7.1 Blood samples…………………………….…………………………………………………… 30
2.7.2 Semen samples………………………….…………………………………………………… 31
2.8 Analyses of samples………………...………………………………………………………… 31
2.8.1 Blood samples………………………………………………………………………………… 31
2.8.1.1 Packed cell volume (PCV)…………………………...................................................... 31
2.8.1.2 Leukocytic indices...................................................... ....................................................... 32
2.8.1.2.1 Total leukocyte count.(TLC) .................................................................................... 32
2.8.1.2.2 Differential leukocyte count (DLC) ..................................................................... 32
2.8.2 Serum samples...................................................................................................................... 32
2.8.2.1 Serum total
protein.............................................................................................................. 32
2.8.2.2 Serum albumin..............................................................
....................................................... 32
2.8.2.3 Serum
urea............................................................................................................................... 33
2.9 Plasma glucose..............................................................
....................................................... 33
2.10 Semen samples..............................................................
....................................................... 33
2.10.1 Appearance.....................................................................
....................................................... 33
2.10.2 Ejaculate
volume............................................................................................................... 34
2.10.3 Sperm mass motility.......................................................
............................................. 34
2.10.4 Sperm individual
motility............................................................................................ 34
2.10.5 Sperm cell
concentration........................................................................................... 34
2.10.6 Incidence of live
sperm................................................................................................. 35
2.10.7 Incidence of abnormal
sperm.................................................................................... 35
2.10.8 Hydrogen ion concentration (pH)
....................................................................... 35
2.11 Climatic
measurements.......................................................................................................... 36
2.12 General experimental
plan................................................................................................... 36
2.13 Statistical analysis.............................................................
....................................................... 38
CHAPTER THREE: EFFECTS OF LEVEL OF FEEDING LUCERNE
HAY AND SEASONAL CHANGES IN THERMAL
ENVIRONMENT ON THERMOREGULATION,
BLOOD METABOLITES AND SEMEN
CHARACTERISTICS................................................................................. 39
3.1 Introduction....................................................... ............................................................................... 39
3.2 Experimental procedure.............................. .............................................................................. 41
3.3. Results....................................................... ........................................................................................ 43
3.3.1. Body weight ( BW) .............................................................................................................. 45
3.3.2. Scrotal circumference (SC) ..............................................................................................
3.3.3 Thermoregulation .....................................................................................................................
45
45
3.3.3.1 Rectal temperature ( Tr) ................................................................................................... 45
3.3.3.2 Respiration rate (RR) ........................................................................................................ 49
3.3.4 Blood metabolites ................................................................................................................ 49
3.3.4.1 Serum total protein............................................................................................................ 49
3.3.4.2 Serum albumin....................................................... ............................................................... 54
3.3.4.3 Serum urea...................................................................... ....................................................... 54
3.3.4.4 Plasma glucose...................................................................................................................... 54
3.3.5 Semen characteristics............................................................................................................. 58
3.3.5.1 Ejaculate volume....................................................... ....................................................... 58
3.3.5.2 Sperm mass motility.......................................................................................................... 58
3.3.5.3 Sperm individual motility............................................................................................... 58
3.3.5.4 Sperm cell concentration................................................................................................. 62
3.3.5.5 Incidence of live sperm ............................................................................................... 62
5.3.5.6 Incidence of abnormal sperm .................................................................................. 62
3.4 Discussion................................................. ............................................................................. 66
3.4.1. Body weight and scrotal circumference................................................................. 66
3.4.2. Thermoregulation..................................................................................................................... 68
3.4.3. Blood metabolites.................................................................................................................... 71
3.4.4. Semen characteristics............................................................................................................ 73
3.5 Summary.............................................. .................................................................................... 80
CHAPTER FOUR: EFFECTS OF EXPOSURE TO SOLAR RADIATION ON
THERMOREGULATION, BLOOD COMPOSITION AND
SEMEN CHARACTERISTICS .... 82
4.1 Introduction....................................................... ............................................................................... 82
4.2 Experimental procedure............................................................................................................. 83
4.3. Results....................................................... ......................................................................................... 86
4.3.1 Effects of exposure to solar radiation........................................................................... 86
4.3.1.1 Thermoregulation................................................................................................................. 86
4.3.1.1.1 Rectal temperature (Tr) ............................................... ................................................ 86
4.3.1.1.2 Respiration rate(RR) .................... ............................................................................... 90
4.3.1.2 Blood composition....................................................... ....................................................... 90
4.3.1.2.1 Packed cell volume (PCV) ......................................................................................... 90
4.3.1.2.2 Leukocytic indices........................................................................................................ 94
4.3.1.2.3 Serum total protein............................... ........................................................................ 97
4.3.1.2.4.Serum albumin....................................................... ........................................................... 97
4.3.1.2.5 Serum urea....................................................... .................................................................... 97
4.3.1.2.6 Plasma glucose......................................... ......................................................................... 101
4.3.1.3 Semen characteristics....................................................... .................................................. 101
4.3.1.3.1 Ejaculate volume....................................................... ....................................................... 101
4.3.1.3.2 Sperm mass motility...................................................................................................... 101
4.3.1.3.3 Sperm individual motility......................................................................................... 105
4.3.1.3.4 Sperms cell concentration............................................................................................ 105
4.3.1.3.5 Incidence of live sperm................................................................................................ 105
4.3.1.3.6 Incidence of abnormal sperm.................................................................................. 109
4.3.1.3.7 Semen pH....................................................... .................................................................... 109
4.3.1.4 Scrotal circumference (SC) ........................................................................................... 109
4.3.2 Effects of exposure to solar radiation and exhaustion test........................... 113
4.3.2.1 Blood composition....................................................... ..................................................... 113
4.3.2.1.1 Packed cell volume(PCV)............................................................................................ 113
4.3.2.1.2 Leukocytic indices....................................................... ................................................. 113
4.3.2.1.3 Serum total protein....................................................... ................................................ 121
4.3.2.1.4 Serum albumin....................................................... .......................................................... 121
4.3.2.1.5 Serum urea....................................................... .................................................................... 125
4.3.2.1.6 Plasma glucose....................................................... ........................................................... 125
4.3.2.2 Semen characteristics.......................................................................................................
4.3.2.2.1 Ejaculate volume .............................................................................................................
130
130
4.3.2.2.2 Sperms mass motility............................................ ....................................................... 130
4.3.2.2.3 Sperms individual motility......................................................................................... 135
4.3..2.2.4 Sperms cell concentration ......................................................................................... 135
4.3.2.2.5 Incidence of live sperm ............................................................................................... 140
4.3.2.2.6 Incidence of abnormal sperm.................................................................................. 140
4.3.2.2.7 Semen pH............................................................................................................................. 145
4.4 Discussion....................................................... ............................................................................... 149
4.4.1 Exposure to solar radiation 149
4.4.1.1 Thermoregulation 149
4.4.1.2 Blood composition 151
4.4.1.3 Semen characteristics 155
4.4.2 Exposure to solar adiation and exhaustion test 160
4.4.2.1 Blood composition 160
4.4.2.2 Semen characteristics 163
4.5 Summary................................ ....................................................................................................... 167
CHAPTER FIVE: EFFECTS OF SEASONAL CHANGES IN 171
THERMAL ENVIRONMENT AND SHEARING ON
THERMOREGULATION, BLOOD CONSTITUENTS
AND SEMEN CHARACTERISTICS................................................
5.1 Introduction....................................................... ............................................................................... 171
5.2 Experimental procedure.................................................... ....................................................... 173
5.3 Results....................................................... ......................................................................................... 177
5.3.1 Effect of season on the responses to shearing....................................................... 177
5.3.1.1 Thermoregulation....................................................... ....................................................... 177
5.3.1.1.1 Rectal temperature(Tr) ................................................................................................. 177
5.3.1.1.2 Respiration rate(RR) .................................................................................................... 180
5.3.1.2 Blood composition............................ ................................................................................ 180
5.3.1.2.1 Packed cell volume(PCV) .......................................................................................... 180
5.3.2.2 Leukocytic indices....................................................... ....................................................... 180
5.3.1.2.3 Serum total protein....................................................... ................................................. 185
5.3.1.2.4 Serum albumin....................................................... .......................................................... 185
5.3.1.2.5 Serum urea................................................................... ....................................................... 185
5.3.1.2.6 Plasma glucose........................................................... ....................................................... 190
5.3.1.3 Semen characteristics....................................................... .................................................. 190
5.3.1.3.1 Ejaculate volume....................................................... ....................................................... 190
5.3.1.3.2 Sperm mass motility....................................................... ............................................. 190
5.3.1.3.3 Sperm individual motility......................................................................................... 190
5.3.1.3.4 Sperms cell concentration........................................................................................... 195
5.3.1.3.5 Incidence of live sperm............................................................................................... 195
5.3.1.3.6 Incidence of abnormal sperm................................................................................... 195
5.3.1.3.7 Semen pH....................................... ...................................................................................
5.3.1.4 Scrotal circumference (SC).........................................................................................
195
195
5.3.2 Effects of season, shearing and fasting on blood composition …........ 201
5.3.2.1 Packed cell volume(PCV) ........................................................................................... 201
5.3.2.2 Leukocytic indices.................................. …...................................................................... 201
5.3.2.3 Serum total protein.................................................. ....................................................... 205
5.3.2.4 Serum albumin.......................................................... .......................................................... 207
5.3.2.5 Serum urea......................................................... .................................................................... 207
5.3.2.6 Plasma glucose.......................................................... .......................................................... 207
5.4. Discussion....................................................... ............................................................................... 211
4.5.1. Seasonal change and shearing ......................................................................................... 211
5.4.1.1 Thermoregulation .............................................................................................................. 211
5.4.1.2 Blood composition ........................................................................................................... 213
5.4.1.3 Semen characteristics ....................................................................................................... 214
5.4.2. Seasonal change, shearing and fasting ...................................................................... 216
5.5 Summary....................................................... ................................................................................... 220
CHARTER SIX: GENERAL DISCUSSION AND CONCLUSIONS…… 223
REFERENCES………………………...…………………………………………..…………………. 232
ARABIC ABSTRACT …………………………..………………………………………………
LIST OF TABLES
Table Page.
1. The chemical composition of the feeds on dry matter basis 29
2. General experimental plan………………………..……………………… 37
3. Experimental plan ……………………………...…………………………… 42
4. The mean values of ambient temperature and relative
humidity during the experimental period ……………….……… 44
5. Effect of level of feeding lucerne hay and season on the
mean body weight (BW) ……………………….………………………… 46
6. Effect of level of feeding lucerne hay and season on scrotal
circumference (SC) …………………………….…………………………… 47
7. Effect of level of feeding lucerne hay and season on rectal
temperature (Tr) at 7:00 a.m. ……………..…………………………… 48
8. Effect of level of feeding lucerne hay and season on rectal
temperature (Tr) at 2:00 p.m. …………………………….…………… 50
9. Effect of level of feeding lucerne hay and season on the
diurnal pattern of rectal temperature (Tr) ………………………… 51
10. Effect of level of feeding lucerne hay and season on
respiration rate (RR) at 7:00 a.m. …………………………………… 52
11. Effect of level of feeding lucerne hay and season on serum
total protein concentration……………………………………..………… 53
12. Effect of level of feeding lucerne hay and season on serum
albumin concentration………………………………………..…………… 55
13. Effect of level of feeding lucerne hay and season on serum
urea concentration…………………………………………………………… 56
14. Effect of level of feeding lucerne hay and season on
plasma glucose concentration………………………………………… 57
15. Effect of level of feeding lucerne hay and season on 59
ejaculate volume………………………………………………………………
16. Effect of level of feeding lucerne hay and season on sperm
mass motility (MM) ……………………………………..………………… 60
17. Effect of level of feeding lucerne hay and season on sperm
individual motility (IM) …………………………..……………………… 61
18. Effect of level of feeding lucerne hay and season on sperm
cell concentration ………………………………………………………… 63
19. Effect of level of feeding lucerne hay and season on the
incidence of live sperm …………………………………...……………… 64
20. Effect of level of feeding lucerne hay and season on the
incidence of abnormal sperm ………………………………..………… 65
21. Experimental plan …………………………………………………..……… 84
22. The prevailing climatic conditions during the experimental
period. ……………………………………………………………….…………… 87
23. Effect of exposure to solar radiation on rectal temperature
(Tr) at 7: 00 a.m. ……………………………………………………..……… 88
24. Effect of exposure to solar radiation on rectal temperature
(Tr) at 2: 00 p.m.………………………………………………………..…… 89
25. Effect of exposure to solar radiation on respiration rate
(RR) at 7: 00 a.m. …………………………………………………………… 91
26. Effect of exposure to solar radiation on respiration rate
(RR) at 2: 00 p.m. …………………………………………………………… 92
27. Effect of exposure to solar radiation on (PCV) ………… 93
28. Effect of exposure to solar radiation on total leukocytes
count (TLC) …………………………………………….……………………… 95
29. Effect of exposure to solar radiation on differential
leukocyte count (DLC) …………………….……………………………… 96
30. Effect of exposure to solar radiation on serum total protein
concentration ………………………………………………………..………… 98
31. Effect of exposure to solar radiation on serum albumin
concentration…………………………………………………………………… 99
32. Effects of exposure to solar radiation on serum urea
concentration…………………………………………………………………… 100
33. Effect of exposure to solar radiation on plasma glucose
concentration…………………………………………………………………… 102
34. Effect of exposure to solar radiation on ejaculate volume 103
35. Effect of exposure to solar radiation on sperm mass motility
(MM) ………………………………………………………………… 104
36. Effect of exposure to solar radiation on sperm individual
motility (IM) ……………………………………………………...…………… 106
37. Effect of exposure to solar radiation on sperm cell
concentration……………………………………………..………… 107
38. Effect of exposure to solar radiation on the incidence of live
sperm……………………………………………………………………… 108
39. Effect of exposure to solar radiation on the incidence of
abnormal sperm ……………………………………………………………… 110
40. Effect of exposure to solar radiation on semen pH ………….. 111
41. Effect of exposure to solar radiation on scrotal
circumference (SC) …………………………….…………………………… 112
42. Effect of exhaustion test on PCV in shaded rams…………… 114
43. Effect of exhaustion test on PCV in unshaded rams………. 115
44. Effect of exhaustion test on total leukocyte count (TLC) of
shaded rams………………………………………………………..…………… 116
45. Effect of exhaustion test on total leukocyte count (TLC) of 117
unshaded rams…………………………………………………………………
46. Effect of exhaustion test on differential leukocytes count
(DLC) of shaded rams……………………………………………………… 119
47. Effect of exhaustion test on differential leukocyte count
(DLC) of unshaded rams……………………………..…………………… 120
48. Effect of exhaustion test on serum total protein concentra-
tion of shaded rams………………………..………………………………… 122
49. Effect of exhaustion test on serum total protein of unshaded
rams……………………………………….………………………… 123
50. Effect of exhaustion test on serum albumin concentration of
shaded rams………………………………………………………………… 124
51. Effect of exhaustion test on serum albumin concentration of
unshaded rams………………………………………………………..…… 126
52. Effect of exhaustion test on serum urea concentration of
shaded rams………………………………………………….………………… 127
53. Effect of exhaustion test on serum urea concentration of
unshaded rams……………………………………………….………………… 128
54. Effect of exhaustion test on plasma glucose concentration
of shaded rams………………………………………………………………… 129
55. Effect of exhaustion test on plasma glucose concentration
of unshaded rams…………………………………………..………………… 131
56. Effect of exhaustion test on ejaculate volume of shaded
rams……………………………………………………………………………… 132
57. Effect of exhaustion test on ejaculate volume of unshaded
rams……………………………………………………………………………… 133
58. Effect of exhaustion test on sperm mass motility (MM) of
shaded rams…………………………………………………………………… 134
59. Effect of exhaustion test on sperm mass motility (MM)of
unshaded rams……………………………………………..………………… 136
60. Effect of exhaustion test on sperm individual motility (IM)
of shaded rams………………………………………………………………… 137
61. Effect of exhaustion test on sperm individual motility
(IM)of unshaded rams……………………………………………………… 138
62. Effect of exhaustion test on sperm cell concentration of
shaded rams…………………………………………………………………… 139
63. Effect of exhaustion test on sperm cell concentration of
unshaded rams……………………………………………………….………… 141
64. Effect of exhaustion test on the incidence of live sperm of
shaded rams………………………………………………………………..…… 142
65. Effect of exhaustion test on the incidence of live sperm of
unshaded rams………………………………………………………………… 143
66. Effect of exhaustion test on the incidence of abnormal
sperm of shaded rams……………………………………………………… 144
67. Effect of exhaustion test on the incidence of abnormal
sperm of unshaded rams……………………………………..…………… 146
68. Effect of exhaustion test on semen pH of shaded rams…….. 147
69. Effect of exhaustion test on semen pH of unshaded rams… 148
70. Experimental plan …………………………………..……………………… 174
71. The prevailing climatic conditions during the experimental
period………………………………………… 176
72. Effect of season and shearing on rectal temperature (Tr) at
7: 00 a.m.………………………………………………………….…………… 178
73. Effect of season and shearing on rectal temperature (Tr) at
2: 00 p.m.…………………………………………………….………………… 179
74. Effect of season and shearing on respiration rate(RR) at 181
7: 00 a.m.………………………………………………………….…………
75. Effect of season and shearing on respiration rate (RR) at 2:
00 p.m.…………………………………………………………….…………… 182
76. Effect of season and shearing on PCV…………………………… 183
77. Effect of season and shearing on total leukocyte count
(TLC) ………………………………………………………………...…………… 184
78. Effect of season and shearing on differential leukocyte
count (DLC) …………………………………………………………………… 186
79. Effect of season and shearing on serum total protein
concentration ……………………………………………………..…………… 187
80. Effects of season and shearing on serum albumin
concentration ………………………………………………..………………… 188
81. Effect of season and shearing on serum urea concentration 189
82. Effect of season and shearing on plasma glucose concen-
tration………………………………………………………………………….….. 191
83. Effect of season and shearing on ejaculate volume …………. 192
84. Effect of season and shearing on sperm mass motility
(MM) …………………………………………………...………………………… 193
85. Effect of season and shearing on sperm individual motility
(IM) …………………………………………..…………………………………… 194
86. Effect of season and shearing on sperm cell concentration 196
87. Effect of season and shearing on the incidence of live
sperm…………………………………………………………………………….… 197
88. Effect of season and shearing on the incidence of abnormal
sperm ………………………………………….…………………… 198
89. Effects of season and shearing on semen pH …………..………… 199
90. Effect of season and shearing on scrotal circumference (SC) ………………………………………………………………………..……… 200
91. Effect of season, shearing and fasting on PCV ……………… 202
92. Effect of season, shearing and fasting on total leukocyte
count (TLC) ………………………………………………………………….… 203
93. Effect of season, shearing and fasting on differential
leukocyte count (DLC) ……………………………………….…………… 204
94. Effect of season, shearing and fasting on serum total protein
concentration ……………………………….……………………… 206
95. Effect of season, shearing and fasting on serum albumin
concentration……………………………………………..…………………… 208
96. Effect of season, shearing and fasting on serum urea
concentration…………………………………………………………………… 209
97. Effect of season, shearing and fasting on plasma glucose
concentration…………………………………………………………………… 210
CHAPTER ONE GENERAL INTRODUCTION
1.1 Economic importance of sheep in Sudan
The domestic sheep (Ovis aries) are widely distributed in the Sudan.
They are characterized by high adaptive capabilities to different climatic
conditions, which include extreme thermal environments and changes in
water and nutritional requirements (Gatenby, 1986a). Compared to other
ruminants, sheep are characterized by early maturation, short
reproductive cycle, utilization of poor pastures and tolerance to drought
conditions and diseases (Ingham et al., 1990). In the tropics, sheep are
raised for meat, milk, skin and wool production (Devendra and Mcleroy,
1987; Payne, 1990).
The Sudan which lies wholly within the tropics is characterized by
different climatic and ecological systems; it possesses some of the major
essentials for successful development of sheep industry which include a
high productive performance. Sheep are raised mainly by nomads; most
of them tend to have a semi-residential system, while small flocks also
exist under transhumance system (Elamin, 1975). In the wet season,
sheep utilize natural pastures and during the dry season they migrate in
pursuit of water and grazing areas (Atabani, 1966; Mohammed, 1989). The indigenous sheep population, which is estimated at 47 millions, are
classified into ecotypes, Desert, Nilotic, Arid Upland and Arid Equatorial sheep (Mcleroy, 1961a,b; Devendra and Mcleroy, 1987). Desert sheep constitute more
than 60% of the sheep population, and they are strictly confined to northern Sudan and semi-arid climatic zones (Atabani, 1966). The most recent survey indicates
that the live sheep and exported mutton represent the highest contribution compared with other species of livestock (Ministry of Animal Resources Annual
Report, 2001), and their contribution to the national economy is well pronounced. The Desert sheep is designated as the most important breed in mutton and milk
production in Sudan. They comprise the majority of live sheep export and constitute an important source of local meat consumption (Muffarih, 1991). The
annual live exported sheep is about one million and the exported mutton is about 4 thousand tons and the locally consumed mutton is more than 11 million heads per
year. The annual export of sheep hide is about 2.5 millions pieces (Elkhidir et al., 1998).
The sheep production in Sudan is influenced by many constraints
other than genotypic factors; due to seasonal migrations of pasturalists,
climatic and nutritional factors constitute major hindrances. The drought
conditions usually result in poor pastures, low productivity and great
losses (Suleiman, 1989).
As sheep in Sudan have high contribution to national economy, it
is worth studying factors that retard their productive and reproductive
potentials. The studies designed to investigate the effects of nutritional
and thermal factors on physiological adaptation and reproductive
performance could yield useful scientific information needed for
upgrading productivity.
1.2. Reproductive performance of sheep under tropical conditions
In the tropics, sheep reproduction is below their genetic potentials,
due to the harsh environment and substandard managemental system
(Devendra and Mcleroy, 1987). Tropical sheep breeds do not exhibit a
seasonal breeding pattern; they are able to breed throughout the year
(Devendra and Mcleroy, 1987; Jainudeen and Hafez, 2000). Their
reproductive performance is influenced by genetic potentials, thermal
environment and nutritional factors (Hafez, 1968; Grell, 1977; Gerlach
and Aurich, 2000).
Rams attain sexual maturity at 5-10 months. They are allowed to
mate naturally at the age of 18-20 months (Gatenby, 1986b). The age at
puberty of ewes is 5-12 months and oestrous cycle is stimulated by the
presence of rams and nutrition (Carles, 1983).The first breeding age of
ewes is at 8-12 months, and the length of their reproductive life is
approximately 5 years (Devendra and Mcleroy, 1987). Thermal stress
reduces food intake and induces testicular degeneration in rams, which
results in the production of low quality semen (Robertshaw, 1985).
However, in ewes thermal stress suppresses conception rate and early
embryonic death may occur (Devendra and Mcleroy, 1987). In sheep,
high plane of nutrition favours early puberty, faster growth and better
libido and short reaction time in rams (Devendra and Mcleroy, 1987).
However, undernutrition during rearing periods delays puberty and sexual
maturity (Chemineau and Terqui, 1985). Sexual maturity may be delayed
even beyond one year of age on a low plane of nutrition or under
unfavourable climatic conditions (Grell, 1977).
1.3. Effects of nutritional factors The general nutritional requirements of sheep are
limited by the voluntary food intake which depends upon their reproductive and productive performance (Khalifa, 1971). However, the utilization of available nutrients is inversely related to the dry matter intake, the digestibility of food and level of dietary protein (Devendra, 1986). The fate of absorbed nutrients is influenced by the environmental conditions and the physiological responses of animals
(Weston, 1966). 1.3.1 Thermoregulation
The intake of food and thermoregulation are integrated and controlled by the hypothalamus, as the lateral hypothalamic area is designated as a feeding centre and the ventromedial one is a satiety centre. In sheep, food intake is regulated by a thermostatic mechanism and there is an inverse relationship between food intake and body temperature and the specific dynamic action (SDA) of food
(Blaxter et al., 1959). Seasonal changes influence food availability and consumption.The food intake, which influences the energy budget and thermoregulation, increases during winter as the maintenance requirements increase, and decreases in hot environment to avoid excess thermal loads (Young, 1981). Energy for maintenance of vital physiological processes is derived from the organic matter in food, while heat
increment of metabolism is associated with the level of feeding and the quality of food (Robertshaw, 1981). When the endogenous heat produced by food intake and metabolism sums with the exogenous heat of the environment, the heat load of the animal increases (Young and Degen, 1981). Consequently, metabolism increases to satisfy the requirements of more oxygen for the increased evaporative heat loss, and eventually the body temperature
rises (Robertshaw and Finch, 1976). In hot environment, high planes of feeding decrease the
heat tolerance of sheep (Blaxter and Boyne, 1982) and increase the rectal temperature and respiration rate (Webster and Johnson, 1968; Sano et al., 1995). However, low levels of feeding which decrease the metabolic heat production (Shmidt-Nielsen, 1995), reduce rectal
temperature and respiration rate (Naqvi and Rai, 1991). During food restriction, the energy requirements of mammals are obtained mainly from mobilization of proteins and fats (Panaretto, 1968). In the fasting state, the availability of energy depends upon utilization of body reserves to prevent tissue catabolism (Payne and Payne, 1987). These energy transformations usually interfere with body thermoregulation in animals (Nangia and Grag, 1988).
1.3.2 Blood metabolites
The changes in the nutritional status of sheep and seasonal changes in the thermal environment may influence the composition of blood.The heart rate, cardiac output and blood volume were higher in fed sheep compared to values obtained in fasting state (Burrin, 1989a). The arterial blood pressure was found to be polyphasic in fed sheep, while it was monophasic in fasting state with low blood volume due to reduction in the supply of blood constituents (Bianca,
1968). The formation of the cellular elements of blood
depends on the nutrients obtained from the animal feed. The plane of nutrition and level of dietary protein affect
erythrocyte count, PCV level and haemoglobin (Hb) concentration (Naqvi and Hooda, 1991). The PCV level and Hb concentration were higher with high plane of nutrition and high dietary protein content, while inanition decreased their levels in sheep (Payne and Payne, 1987). However, Nangia and Garg (1988) reported an increase in PCV level in starved sheep, which was attributed to dehydration as
water and food intake are positively correlated. In sheep the concentration of blood metabolites
represents an integrated index of the nutritional supply in relation to utilization of nutrients and it reflects the nutritional status of the animal. Feeding is the most effective stimulant of the normal diurnal pattern of blood metabolites and hormones in ruminants (Godden and Weekes, 1981); the levels of sugars and nitrogen increase shortly after feeding and fall gradually to the fasting level
(Sharma , 1973). The crude protein content of diet may influence the
nutritional status and the level of blood metabolites in sheep. High and medium levels of crude protein increase digestibility and efficiency of microbial degradation (Gill and Nagi, 1971; Mohan et al., 1987).Consequently, the concentrations of total plasma protein, albumin and urea increased with simultaneous increase in the rate of excretion of urea (Graham and Searl, 1966). However, the intake of low level of crude protein maintained the urea concentration at a constant level in the early stage, which subsequently decreased sharply (Farid, 1985). Although starvation results in excessive break down of body tissues, short-term fasting of Avivastra sheep in hot environment did not induce changes in the concentrations of total protein, albumin and urea (Naqvi and Hooda, 1991). These findings suggest that ruminants are capable of maintaining the level of blood urea during the dry season with scanty food by urea recycling
(Payne, 1990). In ruminants, propionate is the most important glucose
precursor obtained by microbial fermentation of
carbohydrates.When the glucose supply is limited, mobilization of body energy stores for glucose synthesis (and oxidation of spare glucose) will maintain a constant level of blood glucose (Brockman and Laarveld,1986). The utilization of glucose in sheep is efficient and its concentration exhibits a diurnal pattern (Sano et al., 1995). However, due to the continuous absorption of glucose and slow passage of food in the alimentary tract of sheep, it is not regarded as an indicator of the nutritional status (Khalifa, 1971). However, underfeeding in Suffolk wethers decreased blood glucose concentration (Moloney and Moore, 1994). During starvation, the decline in blood glucose level in ruminants is attributed to low concentration of propionic
acid (Naqvi and Hooda, 1991).
1.3.3 Semen characteristics The effects of nutritional stress on the gonads are more
pronounced in female than in male animals, which are encountered only in extreme conditions. A deficiency of energy and/or protein lowers male fertility by depressing semen production and characteristics (Setchell et al., 1965). Various studies in sheep have shown the deterioration of semen characteristics in response to undernutrition (Moule, 1970; Howland, 1975; Martin et al, 1987; Dun and Moss,
1992; Schillo, 1992; Martin and Walkden-Brown, 1995). Various neuro-peptides are involved in the central regulation of food intake(Igbal et al., 2003).Henry et al. (2000) suggested that neuropeptide Y (NPY) in the arcuate nucleus is a good example of the neural regulation for the reproductive axis in response to nutritional status of mammals . In feed restricted animals, NPY can elicit different effects on the secretion of luteinizing hormone (LH). High doses of NPY inhibit the productive axis in male sheep, and in feed restricted sheep NPY lowers LH secretion
(Henry et al., 2000). The nutrients required for sperm production are relatively small
compared to the requirements of growth (McDonald et al., 2002).
However, Hiore and Tomizuka (1965) found that loss of body mass in
male goats was associated with reduction in the output of spermatozoa,
while it had no influences in sheep (Tilton et al., 1964). However, Martin
and Walkden-Brown (1995) reported strong and direct relationships
between plane of nutrition, testicular mass and number of spermatozoa
available in the ejaculates of rams. Martin et al. (1980) observed an
increase in testicular size in association with high planes of nutrition of
sheep. However, prolonged severe undernutrition and poor supply of
energy and protein resulted in decrease in testicular size and production
of lower quality of semen (Knight, 1987).
In Merino rams, Oldham et al. (1978) indicated that an increase of 25% in testicular size resulted in 81% increase in production of spermatozoa.Setchell et al.(1965) noted that severe underfeeding of Merino rams for three months resulted in decreased diameter of seminiferous tubules and the proportion of the seminiferous tubules occupied by the seminiferous epithelium . In Merino rams, feeding for fifteen weeks at 75% or 50% of maintenance resulted in a progressive decline in volume, density and motility of the first ejaculate collected every week (Parker and Thwaites,
1972) . Martin and Walkden-Brown (1995) reported that in mature male sheep and goats, the absolute requirements for protein or energy for production of hormones and gametes is small and the endocrine function of testis is poorly related to nutrition. However, the authors reported hypothalamic pathways controlling gonadotrohpic releasing hormones (GnRH) which respond to nutritional changes. In mature Merino rams, changes in the production of spermatozoa in response to nutritional treatment resulted primarily from alterations in Sertoli cell function (Martin et al. 1994). The authors attributed this to changes in follicle stimulating hormone (FSH) secretion and testicular mass. On the other hand, the effects of nutrition on the activity of the interstitial
tissue were reflected in changes of rates of production of testosterone (Lincoln and Short, 1980). These changes are observed when loss of body and testicular mass is severe resulting in reduced testosterone production (Setchell et al., 1965; Gauthier and Coulaud, 1986; Jainudeen and Hafez,
2000). Rams kept for semen production need maintenance rations, and sub -maintenance level of feeding adversely affected their semen quality (Hafez, 1980). High and low levels of supplementary feeding of Merino rams resulted in marked differences; the high level was associated with superior semen characteristics, except for abnormal forms (Salamon, 1964). However, in hot environment, high levels of feeding resulted in deposition of fats, which may influence the fertility of rams (Hafez, 1980). During 23 weeks of starvation period of a bull, the levels of fructose and citric acid were the only variables of semen plasma constituents affected, as they decreased significantly indicating the rapid response of the accessory glands to nutritional deficiency
rather than testes (Mann and Walton, 1953). An adequate amount of dietary protein is essential for the synthesis of cytoplasmic protein from amino acids precursors which are performed by the spermatocytes (Nakamura et al, 1999; Price et al., 2000). The energy density of food rather than the protein content influences the secretion of gonadotrophins.In mature rams fed low energy rations for prolonged periods, libido and testosterone production were affected much earlier that semen characteristics (Martin et al., 1980). Glucose is needed in spermatogenesis to stimulate the incorporation of lysine into germinal cell protein in the testes, and most of the available glucose is utilized by Sertoli cells (Setchell and Hink, 1976). The semen characteristics are influenced by provision of sufficient amounts of vitamins and minerals in the diet. In mature rams, vitamin A and its precursors are essential to prevent testicular degeneration (Jainudeen and Hafez, 2000), while vitamin E deficiency may lead to degenerative
changes in the seminiferous tubules (Setchell, 1978). Iodine insufficiency reduced libido and addition of copper, cobalt, zinc and manganese improved semen quality in rams (Hafez, 1980). In mammals, calcium is implicated as a regulator for sperm motility (Turner, 2003). Kendall et al. (2000) indicated that in rams supplemented with selenium, zinc and cobalt, the semen had significant increases in motility, proportion of live sperms and proportion of intact
membranes. Garner and Hafez (2000) indicated that in bulls and rams the chemical components of seminal plasma are citric acid, ergothione, fructose, glycerolphosphorylcholine, sorbitol, protein and lipid. The authors also indicated that the chemical components of spermatozoa are nucleic acids, proteins and lipids. The changes in these components influence the semen pH. Milovanov (1962) indicated that semen pH is influenced by the proportion of the alkaline seminal plasma to the acidic epididymal secretions. Terrill (1968) noted that an alkaline reaction of semen was
associated with its poor quality. The effects of nutritional regime on reproductive performance of
laboratory animals have been investigated. In white-footed mice
(Peromyscus Leucopus), testicular regression was reported in response to
food restriction (Young et al., 2000).
1.4 Effects of thermal factors on male animals
In the tropics and subtropics, ambient temperature, humidity, and
solar radiation constitute important factors which influence the
microclimate and physiological responses of animals (El Nouty et al.,
1988). Ambient temperature is a convenient measure of the thermal
environment, as high ambient temperature induces heat stress. If the
effective ambient temperature rises beyond the thermoneutral zone (TNZ)
and exceeds the capacity of the thermoregulatory mechanism, the
increase in body temperature results in an impairment of the process of
spermatogenesis. However, in the temperate zone, the ambient
temperature and photoperiod are the main factors that trigger male
reproductive activity (Haynes and Howles, 1981).
1.4.1 Effects of seasonal changes in thermal environment
The circadian and circanual rhythm in animals are influenced by
changes in environmental conditions.The physiological adjustments allow
for maintenance of homeostasis (Da Silva and Minomo, 1995). Seasonal
changes in thermal environment induce changes in the energy budget and
neuro-endocrine responses of the animal (Payne, 1990; Pineda, 2004).
1.4.1.1 Thermoregulation
The seasonal and diurnal fluctuations in thermal environment may
induce marked changes in thermogenic responses of mammals. In
different seasons, the diurnal pattern adopted by sheep in rectal
temperature and respiration rate coincides with the diurnal changes in
environmental temperature (Menaker and Skin, 1968; Kaushish et al.,
1976; Lowe et al., 2001). The thermolability is controlled by attempts to
maintain homeothermy, a mechanism controlled by the thermoregulation
centre located in the hypothalamus (Hafez, 1968; Jessen and Clough,
1973) and the peripheral cutaneous receptors (Bianca, 1968). Sheep are
thermolabile animals; they are able to tolerate environmental temperature
changes (Terrill, 1968) through their elaborate countercurrent heat
exchange system in the upper respiratory tract (Backer and Hayward,
1968). When exposed to hot environment, sheep, being obligatory
homeotherms, react by increasing rectal temperature and often resort to
panting as the main avenue of evaporative heat dissipation and
maintenance of homeothermy when the ambient temperature is equal to
or greater than body temperature (Macfarlane, 1971 ; Degen, 1977; El
nouty et al., 1988; Patel and Dave, 1990). Also the adaptation of sheep to
hot environment is shown by a shorter steady rate of respiration and onset
of sweating (Hofmeyr et al., 1969).
Water metabolism might influence thermoregulation in mammals.
Sheep increase water intake and water turnover rate during summer in
order to facilitate evaporative heat loss, while in winter the water turnover
is reduced (Macfarlane, 1968).
The endocrine system contributes to thermoregulation. Trenkle
(1978) reported seasonal changes in adrenal and thyroid glands functions
which contribute to heat balance. The activities of both glands increase
during cold, thus contributing in maintenance of homeothermy by
increasing heat production. However, their activities decrease during hot
season, when it is beneficial to decrease endogenous heat production
(Salem et al., 1991). On the other hand, Weekes et al. (1983) observed
increases in the activities of catecholamines, adrenal corticoids and
thyroid hormones on prolonged exposure of sheep to low environmental
temperature so as to increase heat production and heat conservation.
1.4.1.2 Blood composition
Seasonal variations in thermal environment induce several
physiological changes which affect blood composition. The hot
environment increases the cardiac output and skin blood flow in
response to vasodilation which facilitates heat dissipation (Bianca, 1968;
Yeates et al., 1975a), while cold exposure decreases the cardiac output,
arterial blood pressure and skin blood flow due to vasoconstriction
(Hafez, 1968), and it increases hepatic blood flow (Thompson, 1977).
In sheep the circulating blood elements may exhibit seasonal
pattern. In adult sheep adapted to cold, a decrease in erythrocyte count
was observed by Young et al. (1989). Tropical breeds of sheep showed
low levels of packed cell volume (PCV) and haemoglobin concentration
(Hb) during summer (Sahni and Roy, 1972). However, Joshi et al. (1991)
reported a low PCV level in Patanwadi sheep during winter, which was
attributed to the low quality of pasture. In Desert sheep, the studies
performed by Hassan and Hoeller (1966) did not reveal seasonal changes
in PCV level and Hb concentration. However, Alsayed (1997) reported
higher values of these indices in winter compared to values obtained
during dry summer. Hassan and Hoeller (1966) and Alsayed (1997) reported higher total
leukocytes count and higher percentages of neutrophils and monocytes during wet
summer and winter in Desert sheep.
The neuro-humoral system has a seasonal pattern in controlling the
blood metabolites. Exposure of mammals to cold environments increases
the energy requirements for maintenance. Noradrenaline and glucagon
are involved in cold and heat acclimation through modification of lipid
metabolism. In cold acclimated sheep the secretion of noradrenaline and
the responsiveness to its metabolic action increase (Chaffee and Roberts,
1971), while in heat acclimated animals, the secretion of noradrenaline
and its systemic calorigenic action are reduced (Kuroshima et al., 1979).
The hot environment is associated with an increase in cortisol
level and decrease in thyroid secretions, which in turn reduce protein and
carbohydrate metabolism , while cold exposure increases their secretions
and functions (Souza et al., 2002). The concentrations of serum total
protein and albumin, which are used as indices for nutritional status,
increased during wet summer and decreased during winter in Desert
sheep (Alsayed, 1997). The seasonal changes in thermal environment may influence carbohydrate
metabolism and glucose kinetics. Chahal and Ratan (1982) reported an increase in blood glucose concentration during summer and acute cold exposure. The blood
glucose level increases due to liver gluconeogenesis under the control of catecholamines (Thompson, 1977).
1.4.1.3 Semen characteristics
The environment influences the reproductive activity in males
directly through the effects of elevated ambient temperature on the testes,
or indirectly through the photoperiodical changes which induce sequential
changes in the secretions of the gonadotrophins (Lincoln and Richardson,
1998).
In seasonal breeder males, photoperiod controls the reproductive
performance through the secretion of melatonin which stimulates neuro- -
hormonal control of testicular growth and function (Amir et
al.,1986;Colas et al., 1987; Stroud et al., 1992; McMillen et al., 1995;
Tayler and Field ,2004) via the hypothalamic-pituitary testicular axis
(Haynes and Howles, 1981).In temperate environments, under normal
seasonal fluctuations, rams exhibit a positive response to short-day length
( Hanif and William, 1991; Lincoln et al., 1998). However, in the tropics
rams do not show seasonal sexual activity (Amoroso, 1969; Dhillon et al.,
1979; Galil and Galil, 1982; Jainudeen and Hafez 2000; Abdalla, 2001).
The seasonal change in sexual activity is regulated by the
activities of endocrine glands. Gloria et al. (1994) reported that prolactin
modulates the intensity of expression of sexual behaviour in Dorset rams
which is season dependent. However, thyroid hormones are necessary for
the expression of neuro-endocrine mechanisms regulating
photorefractroriness or endogenous reproductive rhythm in males , and
seasonal inhibition of reproductive activity was greatly reduced when
rams were subjected to thyroidectomy (Parkinson and Follett, 1994,
1995). Thyroid hormones maintain a key role in regulating seasonal
reproduction in rams (Parkinson and Follett, 1994), and their deficiency
abolishes normal reproductive and endocrine function in rams (Dickson,
1996).
Souza et al. (2002) reported that in rams the thyroid hormones regulate hexosemonophosphatase activity, which
is an important source of energy for steroidogenesis, and a high level of thyroxine improves semen quality (Gerlach and Aurich, 2001). Tropical breed rams show low levels of thyroxine hormone in late winter and early autumn. However, high levels are shown in late autumn and spring, which is reflected in semen of high quality (Souza et al.,
2002). In Desert breed rams, Galil and Galil (1982 a,b)
reported higher semen quality in wet summer (rainy season) compared to dry summer and winter values. Ibrahim (1997) reported marked seasonal variations in the sexual activity of Egyptian rams and their Chios crosses; higher semen quality was obtained in winter compared with values obtained in summer. Awassi and Border Leicester rams showed high values of seminal traits during autumn and lower values
were reported during winter (Amir and Volcani, 1965b). Seasonal pattern in semen quality was also observed in tropical breed bucks (Degen, 1977; Ali and Mustafa, 1986), and in bulls summer adversely affected semen quality
(Choudhury and Sadhu, 1978). Little research has been conducted on the effects of cold environment on spermatogenesis in farm animals. In some laboratory animals, cooling the testis or scrotum below the freezing point resulted in decapitated sperms and inhibition of spermatogenesis and endocrine function
(Hafez, 1968). 1.4.2 Effects of exposure to solar radiation
Solar radiation constitutes one of the important environmental factors; it includes infrared, ultraviolet and visible light, and it changes throughout the day (Gates, 1968). All vital processes in mammals depend upon solar heat and they are directly influenced by its variations
(Robertshaw, 1985). The thermal consequences of solar heat for animals
depend upon a complex array of factors including the other climatic variables, the coat characteristics, the orientation of the body to the direct solar beam which animals intercept,
and the reflectance of the coat (Clapperton et al., 1965; Cena and Monteith, 1975; Walsbery et al., 1978; Robertshaw,
1981). 1.4.2.1 Thermoregulation
Excess solar heat may alter the general physiological responses and it enhances animals to adjust their body temperature (Das et al., 1999). In mammals, the regulation of body temperature under conditions of high thermal load is a complex problem involving physiological and
behavioural adaptation. The magnitude of heat and prolonged exposure of
animals to solar heat load induce heat stress (Macfarlane, 1968). Heat loss is enhanced by thermal gradient between the body and air (Ingram et al., 1963; Degen, 1977), and the heat absorbed during the day is dissipated by sensible
channels during the night (Robertshaw, 1985). Direct exposure of sheep to solar radiation stimulates
peripheral thermoreceptors (Mitchell, 1977) and increases rectal temperature and respirtation rate (Diwivedi, 1976; Patel and Dave, 1990). In heat stressed sheep, respiration rate varies from 20 to 50 breaths/min up to 300 breaths/min (Terrill, 1968). On exposure of Desert sheep to direct solar heat, the respiration rate reported varied from 88 breaths/min in the morning to 159 breaths/min in the afternoon (Abdelatif and Ahmed, 1992), which coincides with the diurnal fluctuations in ambient temperature and solar radiation. On exposure of Desert sheep to solar radiation under summer conditions, the rectal temperature
in the afternoon increased to 41°C (Abdelatif, 1978). 1.4.2.2 Blood composition
Thermal stress induced by the high intensity of solar radiation could modify blood composition via the neuro-humoral responses. Thermally stressed sheep revealed increases in cardiac output, blood volume and increases in blood flow to the skin, which is associated with vasodilatation (Hales, 1973 a, b). Acute heat exposure of sheep stimulated an increase in cortisol secretion which
tended to decrease gradually (Christeson and Johnson, 1972; Buragohain et al., 1986).Furthermore, prolonged exposure to thermal stress was associated with reduction in the secretion of glucocorticoids (Bareham, 1975), decrease in
food intake and metabolic rate (Singh et al., 1982) . In Barki sheep, an increase in water intake was
reported during summer heat stress associated with haemodilution and lowering of PCV (Hassanain et al., 1996); also low PCV level was reported by Abdelatif (1978) in Desert sheep when experimentally subjected to heat exposure. However, exposure of Desert rams to direct solar heat did not influence the PCV level (Abdelatif and Ahmed, 1992). The increased adrenal activity under thermal stress interferes with immune responses (Joshi et al., 1979); the total leukocyte count was reported to decrease in sheep on prolonged exposure to heat due to adaptation (Gutierlez et
al., 1971). Ahmed (1989) reported an increase in the
concentration of plasma total protein of heat stressed Desert rams, while urea concentration decreased. Guerrini et al. (1982) reported an increase in total plasma protein concentration in Lettelle wethers exposed to solar radiation, which was attributed to decrease in urinary nitrogen However, when Desert sheep were experimentally exposed to acute heat stress, lower values of plasma total protein and albumin were reported, while the urea concentration increased; chronic heat exposure was associated with a
decrease in their levels (Abdelatif, 1978). Exposure to solar radiation may influence the utilization of carbohydrates .Solar heat load increased blood glucose concentration in Barki sheep (Hassanain et al., 1996) and Desert rams (Abdelatif and Ahmed, 1992). Singh et al. (1982) reported a low blood glucose level when Rambouillet and Chokla cross sheep were subjected to summer heat stress. Khogali et al. (1983), using Merino sheep as an experimental model in heat stroke studies, reported an increase in blood glucose concentration in response to controlled thermal
environment of 42-45°C and relative humidity of 40-50% for 120 min.
1.4.2.3 Semen characteristics High thermal load induces physiological stress which
promotes an unfavourable endocrine balance such as general hypofunction of the anterior pituitary. This results in insufficient secretion of gonadotrophins, inadequate secretion of male reproductive hormones and consequently reproductive failure (Hafez, 1968, Lincoln and Richadson,
1998). Solar radiation modifies the reproductive activity in
the male through elevation of ambient temperature and effects of hyperthermia on testicular tissue. However, body temperature responses to heat stress which contribute to testicular cooling, are well characterized in rams (Kastelic et al., 1996). Mount (1979) reported that polypnoea could be evoked by heating the scrotum of Merino rams. In hot environments, thermal stress induced testicular degeneration (Blom, 1969; Kastelic et al., 1996). Extremely high temperatures have adverse effects on spermatogenesis, which in turn contribute to impaired fertility (Ax et al.,
1987). Testicular thermoregulation mechanism in mammals
was reported to be favoured by large scrotal sweat glands and scrotal insulation (Kastelic e.al., 2000). Wierzbowski and Kareta (1993) reported disturbance in testicular thermoregulation in Merino and Romney March rams of wooly scrota under thermal load. However, poorly protected scrota may be receptive to thermal load which adversely affected testicular tissues and consequently semen quality
(Mieusset et al., 1992; Mieusset and Bujan, 1995). Generally, in experimentally induced hyperthermia,
rams produced semen of low quality (Howarth, 1969; Rathore, 1970; Matos and Thomas, 1992). In Desert rams exposed to continuous heating at 43.0°C and 48% RH for different periods, semen samples of abnormal characteristics were obtained (Galil and Galil, 1982 a
,b).Regular collection of semen samples from scrotum insulated in hot bags for 96 hrs in Montadale and Taxel cross rams showed an increased percentage of abnormal
sperms (Ibrahim et al., 2001). 1.4.3 Effects of thermal environment and shearing
The body external insulation consists of coat and air insulation. In all thermal environments, the role of the coat in mammals is to provide protection against penetration of solar radiation and consequently alleviate heat stress, and to reduce heat loss during exposure to cold weather (Folk, 1973). In the tropics, most mammals are of hairy coat (Macfarlane, 1968), and Desert sheep are exclusively haired
(Mcleroy, 1962 c). In the tropics and subtropics, the physical
characteristics of coat are modified in response to seasonal changes in thermal environment. The growth of body coat increases during winter and decreases during summer (Grell, 1977). The colour of the pelage controls the degree of radiant heat reflection, as the white color reflects a higher proportion of radiant heat and the black colour absorbs it (Cena, 1973). At all wave lengths, the reflectivity of a naturally greasy fleece is substantially less than the value for a clean sample of the same origin. Macfarlane (1968) found that the reflectivity of the coat of Merino sheep doubled to 0.7 Kcl/m2/hr when the white cut ends of fibres were exposed after shearing. In temperate breeds of sheep, Clapperton et al. (1965) reported an increase in coat reflectivity from
about 0.25 to 0.5 Kcl/m2/hr after shearing. 1.4.3.1 Thermoregulation
The coat insulation represents thermal resistance to the flow of heat from the skin to the surface of the hair coat, and its presence helped reduce the rise in both rectal temperature and respiratory rate when sheep were exposed to high ambient temperature (Lee, 1950). On exposure of Southdown ewes to infrared irradiation, heavy fleece interfered with the efficiency of evaporative heat loss, while
shearing rendered them more heat tolerant (Webster and Johnson, 1968).
Shearing of sheep increases the reflectivity of fibres (Cena, 1973). In the tropics, shearing of sheep is supposed to alleviate thermal stress and offer a number of husbandry advantages. Shearing of Desert sheep facilitates heat dissipation when environmental temperature is below body temperature (Ahmed, 1989). Exposure of shorn sheep to direct solar heat increased heat gain and body temperature and induced changes in energy balance and fluid dynamics (Macfarlane et al., 1966; Kaushish et al., 1976), with consequent increases in water intake, water turnover rate and extracellular fluids. However, winter shearing markedly influenced the heat balance of sheep (Turnpenny et al., 2000), as body core temperature tended to be lower, particularly in the morning due to enhancement of heat loss
via the skin (Eyal, 1963b; Kaushish et al., 1976). In shorn sheep, the evaporative heat loss by sweating
plays an important role in thermoregulation (Younis et al., 1977; Mittal and Ghosh, 1979), and it complements evaporative loss by panting which assumes a major role, particularly in hot environment (Mclean, 1973). Panting is independent of the coat covering of the animals, as the sheep coat insulates against heat without interfering with the cooling mechanism. In Desert rams, shearing was not associated with a significant reduction in respiration rate
(Ahmed and Abdelatif, 1992). 1.4.3.2 Blood composition
Shearing of sheep may induce physiological and metabolic responses which influence blood volume and
composition. Heat exchange alterations induced by shearing
increased skin blood flow related to vasodilatation and reduction in vasomotor tone (Bianca, 1968).Summer shearing of Merino wethers increased plasma volume (Macfarlane et al., 1966). However, Kaushish et al. (1976) reported an increase in PCV level in autumn in shorn sheep
and a low level of PCV was observed in animals shorn during summer; these findings were attributed to changes in
feed intake. Shearing influences the availability of nutrients for
blood constituents through its effects on feed and water intake, as they are modulated by changes in environmental temperature. Low ambient temperature increased the energy requirements of sheep (Cheeke, 2005b), which was associated with decreased digestibility. However, at high ambient temperature, decreased food intake was associated with the demand for evaporative heat loss and high water turnover rate (Abdelatif and Ahmed, 1992). These changes are usually associated with marked disturbances in the
metabolism of energy and water (Macfarlane, 1968). Shearing of Desert rams under dry summer conditions
increased the total amount of nitrogen ingested and excreted , while the amount of nitrogen retained decreased (Ahmed and Abdelatif, 1992).The authors also reported that shearing was associated with an increase in plasma urea level and a decrease in the level of free fatty acids . In Merino wethers shorn during summer, Macfarlane et al. (1966) reported a decrease in the level of plasma protein. Sano et al. (1995) experimentally subjected shorn Suffolk rams to a cold environment and reported increases in non-protein oxidation and the concentrations of glucose and free
fatty acids. 1.4.3.3 Semen characteristics
In hot environment, heavy wool with high body insulation might be detrimental to the fertility of rams. Shearing might induce lowering of body and/or testicular temperature during hot weather than unshorn rams, with
improvement in fertility (Waites and Voglmayr, 1963). Pijoan and Williams (1984) reported that shearing of rams before the hot
season reduced the adverse effects of heat stress on semen quality. This response is
related to enhancement of cutaneous evaporation and scrotal sweating which provide
an effective thermoregulation mechanism and increase heat tolerance of rams
(Alexander, 1973). However, Hullet et al. (1956) observed a high semen quality and
fertilizing rate in shorn Hampshire, Shropshire Oxford and Corriedale rams during
winter compared to hot season. In unshorn Chokla rams with closely clipped
scrotum, the relative sweating response, compared to the other body regions, was
higher due to the large number of scrotal sweat glands which resulted in lowered body
temperature (Rai et al., 1979).
1.5 Effects of frequency of ejaculation
There is an increasing interest in assessment of the potential for
sperm production in domestic mammals as it may influence the
reproductive performance and breeding capacity (Honmode and Tiwari,
1974). 1.5.1 Frequent ejaculation of semen and assessment of male reproductive
capacity
Removal of large numbers of sperms by exhaustion test is one of
the most adequate methods for estimating sperm production and
reproductive capacity of males (Salamon, 1964 b). Furthermore,
successive ejaculation facilitates evaluation of ejaculatory responses and
perhaps provides evidence of incomplete ejaculation (Pickett and Voss,
1998). Faster ejaculation indicates the superior mating ability of the male,
which is important in rams when female-to-male ratio is relatively high
(Price et al., 1996). In rams, more frequent ejaculation, probably to the
point of exhaustion and refusal of service is necessary for the
measurement of ejaculation capacity and semen characteristics (Salamon,
1962).
Exhaustion test reflects the degree to which males may be used in
intensive breeding programmes and also helps in detecting the effects of
nutritional and seasonal factors (Foote, 1978). Salamon (1964 a) noted
that in Merino rams given high level of supplementary feeding for 6
weeks and subjected to intensive semen collection every 15 weeks for 18
months using artificial vagina, the semen quality was higher compared to
values obtained for the respective low level of feeding group. However,
the author reported low values of sperm motility and sperm cell
concentration and high percent of morphologically abnormal sperm in
high level of feeding group, particularly during mid-summer. On the
other hand, frequent ejaculation of Merino rams, 8 times a day for 8 hours
weekly for 7 weeks accompanied with exposure to 43°C room
temperature, lowered the ejaculate volume and diminished sexual activity
and its effect persisted 2-3 weeks after treatment (Lindsay, 1969).
In seasonal breeder rams, hypoprolactinaemia is associated with the
short photoperiodism and consequently the expression of sexual
behaviour and the frequency of ejaculation (Gloria et al., 1994).
1.5.2 Effects of frequent ejaculation on semen characteristics
Rams can serve several times a day when newly introduced to
ewes; they maintain a higher frequency of mating (2-3 times in few
minutes), but they tend to mate at a rate of once every 1-5 hours when
continuously kept with ewes on heat (Hullet, 1966).
Frequent ejaculation affects the sexual activity and semen
characteristics in different breeds of rams (Danove et al., 1967; Foote and
Trimberger, 1969; Jennings and McWeeney, 1976). However, there are
little or no problems in maintaining a continuous sexual drive, and their
semen was not depleted immediately due to their small ejaculate and
large epididymal reserve (Foote and Trimberger, 1969). A period of 5-6
days is required for passage of the spermatozoa through the epididymis of
the frequently ejaculated rams (Howarth, 1969).
In Merino rams, collection of semen successively, 11 ejaculates per
day for 5 consecutive days using artificial vagina, significantly reduced
ejaculate volume and sperm cell concentration. However, mass motility
and abnormal sperm percent were not affected (Salamon, 1962). On the
other hand, 13 ejaculates per day for 10 consecutive days decreased
ejaculate volume, sperm concentration and the concentration of fructose
and citric acid, while it increased the reaction time (Salamon, 1964 b). In
Najdi rams, repeated electro-ejaculation of semen samples, 2 to 6 times a
day at hourly intervals decreased the ejaculate volume, mass and
individual motility, sperm concentration and live sperm percent, while the
semen pH increased (Galil et al., 1984). Galil and Galil (1982 a,b )
reported lower values of ejaculate volume, mass and individual motility,
sperm concentration and live sperm percent when semen samples were
collected frequently every 30 minutes for 10 consecutive days from
Desert rams. However, abnormal sperm percent and the semen pH
increased and fructose concentration was not affected by increasing
ejaculation frequency. High ejaculation frequency induced specific
biochemical changes in the spermatozoa similar to apoptosis in somatic
cells (Strezezek et al., 1995). Kaya et al. (2002) reported lower ejaculate
volume, sperm concentration and progressive motility when Konya
Merino rams were subjected to 12 days of frequent ejaculation consisting
of 4 consecutive phases, each phase continued for 3 consecutive days.
The changes observed were elevated concentrations of Na and K ions in
seminal plasma.The authors also reported spermatozoal membrane
damage which was associated with high abnormal sperms percent in
addition to inadequate epididymal maturation.
Studies on male goats also indicated the effect of frequent
ejaculation on seminal traits. Ritar et al. (1992) reported lower ejaculate
volume and sperm concentration when Angora bucks were subjected to
successive collection of semen. In West African dwarf bucks,
an increase in frequency of ejaculation significantly decreased ejaculate
volume, sperm concentration and progressive motility, while it
insignificantly increased abnormal sperm percent and semen pH; live
sperm percent was not affected by the treatment (Oyeyemi et al., 2001).
Various studies performed on bulls also indicated that frequent
ejaculation was associated with marked changes in semen characteristics.
Amann and Almiquist (1976) reported that collection of semen six times
a week increased sperms number and motility in Holstein bulls compared
to values obtained following semen collection once a week. However,
using electro-ejaculation method for collection of semen, six successive
collections at 15 minutes intervals from Hereford, Ayershire and
Shorthorn breeds of bulls had no effect on sperm abnormalities (Ghallab
et al., 1981).
Strezezek et al. (1995) found no marked increase in dead sperms
percent in boars in response to frequent ejaculation; however, frequent
ejaculation resulted in mid-piece damage and acrosomal disintegration.
In boars, successive collection of semen reduced resistance for
capacitation in acrosomal membrane of sperm cells due to insufficient
epididymal maturation (Schilling and Vergus, 1987).
Collection of semen once or twice daily did not affect sperm output
in stallion. However, in stallions of sufficient sex drive, several
ejaculations per day reduced their fertility because of insufficient
numbers of sperms. On the other hand, the extragonadal sperm reserve
(EGR) in the epididymal tail was depleted by successive collection of
semen (Pickett and Voss, 1998).
1.6 Objectives The process of reproduction in mammals requires
adequate nutrition and suitable environmental conditions. The basis of adequate nutrition includes availability and continuous ingestion of all nutritionally and biologically valuable substances required by the animal ( McDonald et al., 2002). However, animals have to adapt to extreme
thermal conditions in order to maintain their vital physiological activities.
In the tropics, inadequate forages in dry summer conditions and exposure to extreme thermal environment may influence the general physiological responses of sheep; the cumulative effects of theses factors retard their reproductive performance. Under natural field conditions, Desert rams have to combat the harsh environmental conditions and perform mating throughout the day. Previous studies were carried out to investigate the effects of water and food restriction, exposure to solar radiation and food composition and shearing and exercise on the physiological responses of Desert rams (Ahmed, 1989). The effects of season, exposure to heat stress and exhaustion test on physical and biochemical semen characteristics were also evaluated (Galil and Galil, 1982 a,b). Many studies were performed to assess the effects of season and food intake (Weston, 1966; Godden, and Weekes, 1981; Cheeke, 2005b), and the relationship between level of feeding and environmental temperature on the physiological responses of sheep (Young and Degen, 1981; Naqvi and Rai, 1991; Naqvi and Hooda, 1991). However, few studies have dealt with the effects of nutritional factors on semen characteristics (Hafez, 1980; Lincoln and Short, 1980; Martin and Walkden-Brown, 1995; Jainudeen and Hafez, 2000). This project was designed to investigate the effects of essential nutritional and environmental treatments on the physiological responses and semen characteristics in Desert rams. The studies were
conducted to evaluate the following relationships: 1. The effects of season and level of feeding lucerne hay
on thermoregulation, blood metabolites and semen
characteristics.
2. The effects of exposure to solar radiation on
thermoregulation, blood composition and semen
characteristics and the responses to frequent
ejaculation.
3. The effects of season and the responses to shearing on
thermoregulation, blood composition and semen
characteristics and the responses to fasting.
CHAPTER TWO
MATERIALS AND METHODS
2.1 Experimental animals
A total number of 10 adult entire, sexually mature and apparently healthy Hamari Desert rams (Ovis aries)
were used in the studies. The rams were selected following proper clinical screening of external genitalia and semen
evaluation. The animals were 2-3 years old, with initial mean body weights of 39.0-40.5 kg. The rams bore the
characteristic features of Sudanese Desert sheep. They were deep bodied and haired and had long tapering tails. The coat
hair which was predominantly brown was thick and coarse. The rams were identified individually using ear tags.
Although all the rams were apparently healthy, they were dewormed by an anthelmintic (lvermectin 1ml/50 kg –
ANOUP Company), and were given prophylactic doses of antimicrobial therapy (Ancomycin 200 L.A./5ml/50kg-
ANOUP Company). 2.2 Housing and management
Different systems of housing and management were used in the experiments. In experiment 1, in which the effects of level of feeding lucerne hay were studied, the
animals were accommodated individually in separate pens. They were fed lucerne hay (Medicago sativa) prepared by
drying fresh materials under the sun, and then chopped and mixed thoroughly before feeding. Lucerne hay was offered
ad libitum for rams exposed to direct solar radiation in experiment 2. Free grazing was allowed in experiment 3.
The animals were put to pasture and allowed to graze daily on sorghum residues (Sorghum vulgare) and grasses (Cydom
dacylon) and lucerne. The chemical composition of feeds is given in Table 1.
Table 1. The chemical composition of the feeds (%) on
dry matter basis .
Lucerne
(Medicago sativa) Abu Sabien
(Sorghum vulgare) Dry matter
Metabolizable energy(MJ/kg)
Crude fibre (%)
23 8.48
30.00
10 8.96
38.6
Crude protein (%) 17.5 6.85 Ether extract (%) 0.99 3.00
Nitrogen free extract (%) 40.27 40.00 Ash (%) 11.57 8.52
2.3 Rectal temperature (Tr)
The rectal temperature (Tr) of the rams was measured according to
the experimental protocols, twice daily or twice weekly, in the morning
(7:00 a.m.) and in the afternoon (2:00 p.m.). The Tr was measured to
the nearest ± 0.1ºC using certified mercury -in- glass clinical thermometer
(Wilson-Supreme,Japan), inserted approximately 8 cm into the rectum for
2 min. before the reading was obtained.
2.4 Respiration rate (RR)
The respiration rate (RR) of the rams was measured visually by
counting the flank movements with the aid of stop-watch. The values
were taken for one minute of regular breathing with the animal standing
quietly.
2.5 Body weight (BW)
During the experimental period, the rams were weighed to the
nearest ± 0.1 kg using a spring balance (Salter No. 235-Trade No. 2892 –
England).
2.6 Scrotal circumference (SC) The scrotal circumference was measured according to the method
described by Boundy (1992). Both testicles were pressed downwards into
the scrotal sac, and then using a tape located around the widest part of the
testis , the circumference was measured to the nearest ± 0.1cm.
2.7 Collection of samples
2.7.1 Blood samples
Blood was collected from the rams under aseptic conditions from the jugular vein using plastic disposable
syringes.A sample of 5ml was collected and immediately 1 ml was transferred to a test tube with anti-coagulant (Tri-
sodium ethylene-diamine-tetra-acetate, EDTA) for the measurements of the erythrocytic and leukocytic indices. 2
ml of blood was also transferred to a test tube with anticoagulants, EDTA and sodium fluoride; these samples of
blood were centrifuged for extraction of plasma samples for glucose determination. Sodium fluoride was added to inhibit the enzymatic reactions that influence glucose
concentration (Kelly, 1984). The rest of the blood sample was left at room temperature for 2-3 hrs and then
centrifuged for extraction of serum samples. Haemolysis free serum samples were stored at -20ºC for subsequent
measurements of the concentrations of metabolites. 2.7.2 Semen samples
Semen samples were collected by electro-ejaculation according to the method described by Blackshaw (1954)
using the Raukura ram design of probe (Mark IV OLVET, New Zealand). The rams were controlled lying on the right
side, the rectum was evacuated of faeces and then the electro-ejaculator was lubricated with vaseline and inserted
8 cm into the rectum. An electric charge of 12 volts was applied for 5 seconds, followed by a pause of 8 seconds. This
was repeated 5 times. Semen ejaculated during the pauses was received in graduated tubes. The samples were
examined immediately after collection according to the standard techniques and methods.
2.8 Analysis of samples 2.8.1 Blood samples
The analyses of blood samples were carried out according to the standard methods described in Schalm’s
Veterinary Haematology (Jain, 1986). 2.8.1.1 Packed cell volume (PCV)
The packed column of erythrocytes (PCV), expressed as a percentage of whole blood, was determined in plain
capillary tubes using a microhaematocrit centrifuge (Hawksley, London), operated for 5 min. This method is
more accurate, reproducible and the amount of blood used is minimal.
2.8.1.2 Leukocytic indices 2.8.1.2.1 Total leukocyte count (TLC)
The TLC was performed microscopically under low power (x10 objective) using the improved Neubauer
haemocytometer. 2.8.1.2.2 Differential leukocyte count (DLC)
Blood films were prepared in duplicate. The films were fixed in methanol and stained with Giemsa stain. The leukocytes were differentiated and counted using oil
immersion lens (x100 objective) of light field microscope. The values are reported as a percentage from the counting
of 100 leukocytes from each slide. 2.8.2 Serum samples
The serum concentrations of total protein, albumin and urea were determined using the spectrophotometer
(JENWAY-6150 .U.V.USA). 2.8.2.1 Serum total protein
Serum total protein concentration was determined by the Biuret reagent method described by King and Wooton
(1965). In this method, the peptide bonds of plasma proteins diluted with isotonic solution of sodium chloride react with alkaline copper sulphate to give a violet colour. The optical
densities were measured at a wave length of 540 nm. 2.8.2.2 Serum albumin
Serum albumin concentration was determined by the colorimeteric method of Bartholomew and Delany (1966), using bromo-cresol green (BCG) reagent. BCG has been
used at pH 3.8-5.0 depending upon the dye binding reaction. Brophenol-blue colour changes from yellow to blue on
adding alkalis. The blue colour indicates the divalent anion and the yellow colour is formed from undissociated phenol
group which forms the blue complex with albumin. The optical densities were measured at a wave length of 637nm.
2.8.2.3 Serum urea Serum urea concentration was determined by the
colorimetric method of Evans (1968) using diacetyl monoxime (DAM) and thiosemicarbazide (TSC) reagents.
DAM when treated with urea decomposes to give hydroxylamine and diacetyl which condenses with urea.
TSC, ferric ions and strong acids are added to catalyse the reaction forming a complex colour. The optical densities
were measured at a wave length of 520 nm. .2.9 Plasma glucose
Plasma glucose concentration was determined by the colorimetric method using a commercial kit (Aromex-
Amman, Jordon). This method was adopted by Barham and Trinder (1972). The enzymatic oxidation occurs in the
presence of glucose oxidase. The hydrogen peroxide formed reacts with phenol and 4-amino-phenazone to produce a red
violet dye as an indicator. The optical densities were measured at a wave lengeth of 540nm.
Glucose Glucose + O2 + H2O ─────→ Gluconic acid + H2O
Oxidase
2.10 Semen samples
Semen samples were analyzed according to the methods described
by Boundy (1992, 1993) and Ax et al. (2000).
2.10.1 Appearance
Immediately after collection of semen samples, the colour and
consistency were determined visually for abnormal colour and whether
the sample is thick or watery. Semen samples of rams are usually of
creamy or milky colour; brown colour indicates the presence of blood,
while greenish colour indicates the presence of pus due to infection of the
genital tract.
2.10.2 Ejaculate volume
The volume of semen sample was determined after collection using
graduated tubes. The graduation ranged from 0.5 to 10 ml. The volume
of the sample was measured to the nearest ± 0.1 ml.
2.10.3 Sperm mass motility (MM)
Mass motility (wave motion) estimation was carried out
immediately after the collection of semen sample.Using Pastuer pipette a
drop of undiluted semen was delivered on an uncovered clean warmed
slide and examined under low power (x10 objective) using a binocular
light microscope. According to the wave motion of swirling bands of
spermatozoa, the scores ranging from 0 (indicating immotile
spermatozoa) to 5 (indicating high motility) were recorded.
2.10.4 Sperm individual motility (IM)
Estimations of individual motility were carried out by diluting a
drop of semen by 4 drops of normal saline (0.9% NaCl). A drop of the
diluted semen was situated on a warm slide covered by a cover slip and
examined microscopically (x45 objective). Estimates of progressively
motile cells were made.
2.10.5 Sperm cell concentration
For the determination of the concentration of spermatozoa in
semen samples, the red cell counting apparatus was used. Semen sample
was drawn by the pipette until the mark 0.5, and then formol-saline was
drawn until the mark 101. After gentle shaking and waiting for 5 min, the
first 4 drops were discarded, and then a drop was introduced under the
cover glass of the heamocytometer. After settlement of the spermatozoa,
they were counted microscopically (x45 objective), adopting the method
used for counting red cells. The total number of spermatozoa was
multiplied by 109 to obtain the number of sperms in one millilitre of
normal semen sample.
2.10.6 Incidence of live sperms
Immediately after the estimation of the sperm motility, a drop of
semen was mixed on a warm slide with 4 drops of warm Nigrosin-Eosin
stain (Hancock, 1951), and a thin smear was prepared. The dead sperm
head takes up the eosin stain, whereas the live sperm does not. The
difference was assessed against the dark background imparted by the
Nigrosin stain and the percentage count was made of the live sperms
under oil immersion lens (x100 objective).
2.10.7 Incidence of abnormal sperms
The slide used to determine live sperm percent was used to
determine morphologically abnormal sperm. Abnormalities in
spermatozoal morphology are divided into primary and secondary
abnormalities. Primary abnormalities are abnormal size and form of the
head, abaxial tails , double heads, double tail, dag tail (tail tightly coiled
around the midpiece) . which develop during spermatogenesis. Secondary
abnormalities are usually associated with distal droplets, bent and coiled
tails which develop during epididymal transit. All these abnormalities
were calculated as percentage from 200 randomly examined spermatozoa
under oil immersion lens (x100 objective).
2.10.8 Hydrogen ion concentration (pH)
The indicator papers (E. Merk Company, Darmstadt, Germany)
were used to determine the pH of semen samples. The papers of pH
range of 5.2 to 8.0 were used by applying a drop of semen sample and the
colour developed was matched with the standard colour.
2.11 Climatic measurements
The daily maximum, minimum and mean ambient temperature (Ta)
and the relative humidity (RH) readings were obtained from Shambat
Meteorological Centre located about 500 meters or 1 Km from the
experimental site. The data were utilized in computation of the mean
values of temperature and humidity during the experimental periods.
2.12. General experimental plan
The general experimental plan is outlined in Table 2.Three
experiments were designed and conducted to study the effects of seasonal
changes in thermal environment and level of feeding lucerne hay, the
effects exposure to solar radiation and exhaustion test, and the effects of
seasonal changes in thermal environment and shearing and exhaustion
test on thermoregulation, blood composition and semen characteristics of
Sudanese Desert rams. The details of the experimental procedure for
each experiment are presented in the specific chapter.
In each experiment, an adaptation period of 14 days was allowed
before the commencement of proper measurements. During this period,
the animals became used to the experimental conditions, handling and
collection of blood and semen samples.
In experiment 1, during summer and winter, the animals were divided into 3 groups of 3 rams each and kept
individually in shaded pens. They were fed high, medium and low levels of chopped leucerne hay and had free access
to water. In each season, Tr and RR were measured daily and blood and semen samples were collected weekly for 3
months. In experiment 2, the animals were divided into 2 groups of 4 rams each (A and
B). Group A animals were shaded while group B animals were exposed to solar
radiation. Chopped lucerne hay and water were offered ad libitum. Measurements of
rectal temperature (Tr) and respiration rate (RR)
Table 2. General experimental plan
Exp.No. Treatment Season
No. of animals
used
ExperimetalPeriod (week)
Measurements
1 Effects of Feeding level of
Summer and
winter
9 12 • Tr,RR
• Blood parameters
lucerne hay • Semen
characteristics
• Scrotal
circumference
2
Effects of exposure to
solar radiation
and exhaustion
test
Wet summer
8 5 • Tr,RR
• Blood parameters
• Semen
characteristics
• Scrotal
circumference
3 Effects of
shearing and fasting
Summer and
winter
8 5 • Tr,RR
• Blood parameters
• Semen
characteristics
• Scrotal
circumference
were recorded daily. Blood and semen samples were collected weekly for
three weeks. During the fourth week, the exhaustion test of rams was
performed for 3 successive days by frequent ejaculation.
In experiment 3, during summer and winter, the animals were
divided into 2 groups of 4 rams each (A and B). Group A animals had
intact pelage and group B animals were shorn. All animals were allowed
to graze the available pasture at the University Farm in Shambat with free
access to water.During the experimental period, weekly measurements of
Tr and RR were performed. Blood and semen samples were collected
weekly for 4 weeks. During the fifth week the animals were subjected to
fasting , blood samples were collected before and after fasting.
2.13. Statistical analysis
The statistical analysis was performed using the Statistical
Analysis System (SAS, 1997). The analysis of variance (ANOVA) test
was used to evaluate the effect of season and level of feeding lucerne hay
,the effects of exposure to solar radiation and exposure to solar radiation
and exhaustion test and the effects of season, shearing and fasting on
thermoregulation, blood composition and semen characteristics of Desert
rams.
CHAPTER THREE
EFFECTS OF LEVEL OF FEEDING LUCERNE HAY
AND SEASONAL CHANGES IN THERMAL ENVIRONMENT
ON THERMOREGULATION, BLOOD METABOLITES
AND SEMEN CHARACTERISTICS
3.1 Introduction
In the tropics, seasonal changes in climatic conditions and forage quality and
quantity constitute constraints to sheep production (Rowe, 1989). Although sheep are
allowed to graze freely, sufficient nutrient requirements for maintenance and
production may not be available (Devendra and Mcleroy, 1987). The energy density
of food is necessary for maintenance of the body functions (McDonald et al. 2002),
and the productive and reproductive state of sheep may influence the energy
requirements (Antounovic et al., 2002). The food intake and efficiency of energy
utilization are altered by effective ambient temperature (Gillespie, 1998). The plane of
nutrition influences the energy budget and the thermoregulatory capacity of sheep and
other species of mammals (Robertshaw, 1985).
The spermatogenic cycle in rams is 10 days (Stabenfeldt and Edqvist, 1993)
and the process of spermatogenesis which involves mitotic proliferation, meiotic
division and differentiation of the haploid spermatids and maturation of spermatids
into spermatozoa is about 40 days (Bilaspuri and Guraya,1986). The process of
spermatogenesis is sensitive to physiological changes brought about by thermal and
nutritional stresses (Evans and Maxwell, 1987). Various studies have demonstrated
the deleterious effects of high thermal load on spermatogenesis (i.e. testicular
degeneration and abnormal sperms) under temperate (Gordon, 1997; Jainudeen et al.,
2000) and tropical environmental conditions (Chemineau et al., 1991; Abdalla, 2001).
These effects may have serious implications regarding fertility of rams and
reproductive activity of sheep during hot dry summer conditions. Early investigations
assessed the sexual function of inadequately fed males from semen samples and from
histological studies of the testes (Moule, 1963; Setchell et al., 1965). A high level of
feeding was shown to improve semen quality and increase scrotal circumference
(Sutama and Edey, 1985). However, a low plane of nutrition (insufficient energy
and/or protein) usually induces low male fertility (Martin and Walkden-Brown, 1995),
while severe undernutrition reduced semen quality and scrotal circumference
(Thwaites and Hammond, 1989; Chemineau et al., 1991). Controlled malnutrition in
the form of providing submaintenance diets to sheep during periods of severe feed
shortage is a nutritional exercise which has serious implications on rams reproduction.
Accordingly, a temporal sterility may persist for several weeks and initiation of new
spermatogenic cycle may be delayed before sperm production reaches the maximal
level (Evans and Maxwell, 1987).
It is desirable to improve our understanding of the various physiological
mechanisms which influence fertility of rams. The effect of seasonal changes in
thermal environment and the interaction between thermal load and nutrition warrant
investigation.Therefore, this experiment was designed to investigate the effects of
level of intake of lucerne hay (Medicago sativa), an important tropical legume, on the
physiological responses and seminal traits of Desert rams in different seasons.
3.2 Experimental procedure
The effects of feeding three levels of chopped lucerne hay on
thermoregulation, blood metabolites and semen characteristics were investigated
during tropical winter and summer environmental conditions. Nine entire adult
Desert rams aged 2-3 years and weighing 39.0-46.5 kg have been used in the studies.
They were randomly assigned to 3 groups of 3 rams each, to high, medium and low
level of feeding. The three groups of rams were used in studies performed under
winter and summer climatic conditions. The investigations were carried out for 3
months during winter (December 1999 to March 2000) and summer (June to
September, 2000).The rams were allowed an adaptation period of 2 weeks and were
accommodated individually in two rooms in the animal pens. Appropriate feeding and
watering facilities were used.
The average value for ad libitum levels of dry matter intake for the rams was
considered as the high level of feeding, 100% (1200 gm), and accordingly the
medium level, 66% (800 gm) and the low level , 33% (400 gm) of feeding were
calculated. The amount of food intake was determined by subtracting the refused food
amount from that given. During summer, the same protocol of feeding regimen was
applied. Fresh tap water was continuously available during the experimental period.
The maintenance requirements (Mm) for sheep kept indoors is calculated as
Mm/kg = 1.2 + 0.1 W (body weight) (McDonald et al., 1981). The initial average
body weight of rams obtained was 43.22kg, accordingly the maintenance allowance
was 6.81686 MJ/day.
The metabolizable energy (ME) of lucerne hay in ruminants was calculated as
8.80 MJ/kg (Suleiman and Mabrouk, 1999). The amount of lucerne hay needed to
satisfy the maintenance requirements was computed as 774.84gm. Therefore the
medium level of feeding used in the present
Table 3.1. Experimental plan
Experimental
period Treatment
Daily
measurements
Weekly
sampling and
measurements
Analysis
Winter
(December-
March 2000)
High, medium
and low levels
of feeding
Tr (7:00 a.m.)
Tr (2:00 p.m.)
RR (7:00 a.m.)
Blood
Semen
Body weight
Scrotal
circumference
Blood
metabolites
Semen
characteristics
Summer
(June –
September
2000)
High, medium
and low levels
of feeding
Tr (7:00 a.m)
Tr (2:00 p.m)
RR (7:00 a.m)
Blood
Semen
Body weight
Scrotal
circumference
Blood
metabolites
Semen
characteristics
experiment could provide approximately the maintenance requirements, whereas the
low level of feeding imposed was below maintenance.
The measurements of rectal temperature (Tr) and respiration rate (RR) were
performed daily. Tr was measured at 7:00 a.m. and 2:00 p.m. during winter and
summer for 12 weeks and RR was measured at7: 00 for 9 weeks in each season.The
body weights of rams and scrotal circumference were measured weekly. In each
season, during the experimental period, blood and semen samples were collected
weekly at 8:00 a.m. During each season, blood samples were collected for 12 weeks
and semen samples were obtained for 10 weeks.
Serum samples were used for the determination of the concentrations of total
protein, albumin and urea and plasma samples were used for the determination of
glucose concentration. Semen samples were used for the measurements of ejaculate
volume, mass and individual motility, sperm cell concentration, live sperm (%) and
abnormal sperm (%).The experimental plan is shown in Table 3-1.
3.3. Results
The effects of level of feeding lucerne hay and season on body weight,
thermoregulation, blood metabolites and semen characteristics were studied in Desert
rams. The results obtained are presented as means ± S.E.M.
The prevailing climatic conditions during experimental period are presented in
Table 3.2. The ambient temperature and relative humidity values were higher during
summer compared to the respective values reported during winter conditions.
Table 3.2 The mean values of ambient temperature Ta (ºC) and relative humidity,
RH (%) during the experimental period.
Ta (ºC) Season
Max. Min. Mean
RH (%)
( Mean)
Winter
(December/99 -March/
2000)
31.58
± 1.51
15.83
± 1.66
23.71
± 7.88
28.17
± 4.57
Summer
(June - September /2000)
38.23
± 2.61
25.59
± 1.18
31.91
± 6.32
42.09
± 11.49
3.3.1. Body weight (BW)
Table 3.3 shows the results of the effect of level of feeding lucerne hay and
season on the mean body weight (BW) of rams. The rams fed low level of lucerne hay
maintained significantly lower BW during summer (p< 0.01) and winter (p< 0.001).
All the experimental groups of rams had significantly (p<001) higher values of mean
BW in winter compared to the respective values measured in summer.
3-3-2 Scrotal circumference (SC)
Table 3-4 shows the results of the effects of level of feeding
lucerne hay and season on scrotal circumference. In both seasons, the
rams had significantly (p<0.01) lower scrotal circumference with the low
level of feeding compared to the higher feeding levels. The rams
maintained on high level of feeding had significantly (p<0.01) higher
values of scrotal circumference during winter compared to the values
obtained in summer. However, with medium and low levels of feeding,
the changes related to season did not attain the level of significance. 3.3.3. Thermoregulation
3.3.3.1. Rectal temperature (Tr)
Table 3.5 shows the results of the effect of level of feeding lucerne hay and
season on rectal temperature (Tr) values at 7:00 a.m. Rams fed low level of lucerne
maintained significantly (p<0.05) lower Tr values during winter and summer
compared to the values obtained for the high and medium level groups. However, for
each plane of nutrition, the decrease in Tr during winter did not attain the level of
significance.
Table 3.3 Effects of level of feeding lucerne hay and season on the mean body
weight, BW (kg) of Desert rams .
(n = 36 ,mean ± S.E.M.)
Season Level of feeding
Winter Summer
SL
High A 44.16 a
± 0.33
A 42.16 b
± 0.40 ***
Medium B 39.57
± 0.40a
B 38.40 b
± 0.37 ***
Low B 35.70 a
± 0.39
B 34.45 b
± 0.60 ***
SL ** ***
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
** : Significant at p< 0.01.
*** : Significant at p< 0.001.
Table 3.4 Effects of level of feeding lucerne hay and season on scrotal circumference , SC (cm) in Desert rams.
( n = 30 ,mean ± S.E.M.) .
Level of feeding Season SL
Winter Summer
High
A 32.52 b
± 0.40
A 30.75 a
± 0.19 **
Medium
B 30.55 a
± 0.35
AB 29.72 a
± 0.42 NS
Low
B27.77 a
± 0.51
B 28.77 a
± 0.45 NS
SL ** **
Mean values within the same row bearing different superscripts (small) are significantly different.
Mean values within the same column bearing different superscripts (capital) are significantly different.
SL: Significance level.
**: Significant at p<0.01.
NS: Not significant.
Table 3.5 Effects of level of feeding lucerne hay and season on rectal temperature,
Tr (ºC) of Desert rams at 7:00 a.m.
(n = 252, mean ± S.E.M.).
Season Level of feeding
Winter Summer SL
High A 37.98 a
± 0.04
A 38.12 a
± 0.02 NS
Medium A 37.74 a
± 0.05
B 37.89 a
± 0.04 NS
Low B 37.40 a
± 0.06
B 37.54 a
± 0.10 NS
SL * *
Mean values within the same row bearing similar superscripts (small) are not significantly different.
Mean values within the same column bearing different superscripts (capital) are significantly different.
SL: Significance level.
* : Significant at p<0.05.
NS: Not significant
Table 3.6 shows the results of the effect experimental treatments on Tr values
measured at 2:00 p.m. In each season, the rams had significantly (p< 0.01) lower Tr
values with low level of lucerne hay. For each nutritional level, the afternoon Tr value
was significantly (p<0.01) higher during summer compared to the respective winter
value.
The results of the effects of level of feeding lucerne hay and season on the
diurnal pattern of Tr are shown in Table 3.7. The data indicate that during summer,
the afternoon values of Tr were significantly (p<0.001) higher with each level of
feeding compared to the respective values obtained for winter.
3.3.3.2 Respiration rate (RR)
Table 3.8 shows the results of the effect of level of feeding lucerne
hay and season on RR at 7:00 a.m. RR was significantly (p<0.05) lower
with low level of feeding during summer compared to the values reported
for the medium and high levels. All groups of rams showed significantly
(p<0.01) higher RR values during summer compared to respective winter
values.
3.3.4 Blood metabolites
3.3.4.1 Serum total protein
Table 3-9 shows the results of the effects of level of feeding
lucerne hay and season on serum total protein concentration. During
summer, the feeding level had no significant effect on serum total protein
concentration. However, during winter, feed restriction significantly (p<
0.05) lowered serum total protein concentration. For the high level of
feeding, the rams had significantly (p<0.05) lower serum total protein
level during summer compared to the respective value measured in
winter. However, the changes in environment from summer to winter did
not influence the serum
Table 3.6 Effects of level of feeding lucerne hay and season on rectal temperature,
Tr (ºC) of Desert rams at 2:00 p.m.
(n = 252, mean ± S.E.M.).
Season Level of feeding
Winter Summer
SL
High A 38.72 b
± 0.03
A 39.10 a
± 0.05 **
Medium A 38.64 b
± 0.04
A 38.99 a
± 0.06 **
Low B 38.39 b
± 0.04
B 38.76 a
± 0.05 **
SL ** **
Mean values within the same row bearing different superscripts (small) are significantly different.
Mean values within the same column bearing different superscripts (capital) are significantly different.
SL: Significance level.
**: Significant at p< 0.01.
NS: Not significant
Table 3.7 Effects of level of feeding lucerne hay and season on the diurnal pattern of
rectal temperature, Tr (ºC) of Desert rams.
(n = 252, mean ± S.E.M.).
Level of
feeding Season 7:00 a.m. 2:00 p.m. SL
Summer 38.12 b
± 0.02
39.10 3 a
± 0.05 ***
High
Winter 37.98 b
± 0.04
38.72 a
± 0.03 **
Medium Summer 37.89 b
± 0.04
38.99 a
± 0.06 ***
Winter 37.74 b
± 0.05
38.64 a
± 0.04 **
Summer 37.54 b
± 0.10
38.76 a
± 0.05 ***
Low
Winter 37.40 b
± 0.06
38.39 a
± 0.04 ***
For each season, mean values within the same row bearing different superscripts are
significantly different.
SL: Significance level.
**: Significant at p< 0.01.
***: Significant at p< 0.001.
Table 3.8 Effects of level of feeding lucerne hay and season on respiration rate, RR
(breaths/min.) of Desert rams at 7:00 a.m.
(n = 189, mean ± S.E.M.) .
Level of feeding Season SL
Winter Summer
High
A 17.83 b
± 0.24
A 25.02 a
± 0.82 **
Medium
A 18.70 b
± 0.38
A25.40 a
± 0.66 **
Low
A 16.40 b
± 0.28
B 22.39 a
± 0.73 **
SL NS *
Mean values within the same row bearing different superscripts (small) are significantly different.
Mean values within the same column bearing different superscripts (capital) are not significantly different.
SL: Significance level.
**: Significant at p < 0.01.
*: Significant at p < 0.05.
NS: Not significant.
Table 3.9 Effects of level of feeding lucerne hay and season on serum total protein
concentration (g/dl) in Desert rams.
(n = 36, mean ± S.E.M.).
Season Level of feeding
Winter Summer
SL
High
A 7.84 a
± 1.96
A 7.46 b
± 0.10 *
Medium
B 7.51 a
± 0.10
A 7.43 a
± 0.13 NS
Low
B 7.33 a
± 0.12
A 7.45 a
± 0.14 NS
SL * NS
Mean values within the same row bearing different superscripts (small) are significantly different.
Mean values within the same column bearing different superscripts (capital) are significantly different.
SL: Significance level.
*: Significant at p < 0.05.
NS: Not significant
total protein concentration significantly with medium and low levels of
feeding.
3.3.4.2 Serum albumin
Table 3-10 shows the results of the effect of level of feeding
lucerne hay and season on serum albumin concentration. During summer
and winter, the rams fed low level of lucerne hay had significantly
(p<0.05) lower serum albumin level compared to values measured for the
other groups. However, with all levels of feeding, the serum albumin
level was significantly (p<0.05) lower in summer compared to winter
values.
3-3-4-3 Serum urea
Table 5-11 shows the results of the effect of level of feeding
lucerne hay and season on serum urea concentration. During summer and
winter, the feeding level had no significant effect on serum urea
concentration. In rams fed low level of lucerne hay, the serum urea
concentration was significantly (p<0.01) higher in summer compared to
the respective value obtained in winter.
3-3-4-4 Plasma glucose
Table 3-12 shows the results of the effect of level of feeding
lucerne hay and season on plasma glucose concentration. In both seasons,
the level of feeding did not influence significantly the plasma glucose
concentration. For each level of feeding, the season had no significant
effect on plasma glucose level. However, the values measured during
summer were higher with high and low level of feeding lucerne hay
compared to the respective values obtained in winter.
Table 3.10 Effects of level of feeding Lucerne hay and season on serum albumin
concentration (g/dl) in Desert rams .
(n = 36, mean ± S.E.M).
Season Level of feeding
Winter Summer
SL
High
A 3.57 a
± 0.04
A 3.45 b
± 0.04 *
Medium
B 3.50
± 0.04a
B 3.37 b
± 0.05 *
Low
AB 3.54 a
± 0.04
B 3.38 b
± 0.05 *
SL * *
Mean values within the same row bearing different superscripts (small) are significantly different.
Mean values within the same column bearing different superscripts (capital) are significantly different.
SL: Significance level.
* : Significant at p<0.05.
Table 3.11 Effects of level of feeding lucerne hay and season on serum urea
concentration (mg/dl)in Desert rams .
(n = 36, mean ± S.E.M.).
Season Level of feeding
Winter Summer
SL
High
A 22.94 a
± 1.11
A 25.46 a
± 1.34 NS
Medium
A 21.38 a
± 0.94
A 25.12 a
± 1.51 NS
Low
A 19.59 b
± 0.71
A 24.59 a
± 1.41 **
SL NS NS
Mean values within the same row bearing different superscripts (small) are significantly different.
Mean values within the same column bearing similar (capital) superscripts not are not significantly different.
SL: Significance level.
**: Significant at p<0.01.
NS: Not significant
Table 3.12 Effects of level of feeding lucerne hay and season on plasma glucose
concentration (mg/dl) in Desert rams .
(n = 36 ,mean ± S.E.M.) .
Level of feeding Season SL
Winter Summer
High
A 64.91 a
± 2.96
A 67.20 a
± 1.63 NS
Medium
A 62.18 a
± 2.55
A 62.01 a
± 1.38 NS
Low
A 59.74 a
± 2.71
A 61.62 a
± 1.59 NS
SL NS NS
Mean values within the same row and column bearing similar superscripts are not significantly different.
SL: Significance level.
NS: Not significant
3-3-5 Semen characteristics
3-3-5-1 Ejaculate volume
Table 3-13 shows the results of the effect of level of feeding
lucerne hay and season on ejaculate volume. In animals fed low level of
lucerne hay, the ejaculate volume was significantly (p<0.01) lower during
summer and winter compared to the values reported for the other groups.
With each level of feeding, the ejaculate volume was higher during winter
compared to the respective summer value. The increase in ejaculate
volume was significant with high and medium levels of feeding (p<0.01)
as well as low level of feeding (p<0.05).
3-3-5-2 Sperm mass motility (MM)
Table 3-14 shows the results of the effect of level of feeding
lucerne hay and season on sperms mass motility, MM. During summer,
the sperm MM was significantly (p<0.05) lower with medium and low
levels of feeding. During winter, the level of feeding had no significant
influence on sperm MM. However, with each level of feeding, the sperm
MM was significantly (p<0.001) higher during winter compared to the
respective values obtained during summer.
3-3-5-3 Sperm individual motility (IM)
Table 3-15 shows the results of the effect of level feeding lucerne
hay and season on sperm individual motility, IM. The percentage of
sperm IM was significantly lower with medium and low levels of feeding
g during winter (p<0.01) and summer (p<0.05), respectively. With all
levels of feeding, IM of the sperms was significantly (p<0.001) higher
during winter compared to summer values.
Table 3.13 Effects of level of feeding lucerne hay and season on ejaculate volume
(ml) in Desert rams .
(n = 30, mean ± S.E.M.) .
Season Level of feeding
Winter Summer
SL
High
A 1.96 a
± 0.09
A 1.66 b
± 0.09 **
Medium
A 1.98 a
± 0.10
A 1.58 b
± 0.09 **
Low
B 1.58 a
± 0.08
B 1.33 b
± 0.07 *
SL ** **
Mean values within the same row bearing different superscripts (small) are significantly different.
Mean values within the same column bearing different superscripts (capital) are significantly different.
SL: Significance level.
*: Significant at p< 0.05.
**: Significant at p< 0.01.
Table 3.14 Effects of level of feeding lucerne hay and season on sperm mass
motility, M M (0 – 5) in Desert rams.
(n = 30, mean ± S.E.M.) .
Season Level of feeding
Winter Summer
SL
High
A 4.65 a
± 0.08
A 3.66 b
± 1.41 ***
Medium
A 4.42 a
± 0.08
B 2.86 b
± 1.51 ***
Low
A 4.32 a
± 0.10
B 3.02 b
± 1.34 ***
SL NS *
Mean values within the same row bearing different superscripts (small) are significantly different.
Mean values within the same column bearing different superscripts (capital) are significantly different.
SL: Significance level.
*: Significant at p<0.05.
***: Significant at p< 0.001.
NS: Not significant.
Table3.15 Effects of level of feeding lucerne hay and season on sperm individual motility, IM (%) in Desert rams .
(n = 30, mean ± S.E.M.).
Season Level of feeding
Winter Summer
SL
High
A 76.67 a
± 2.24
A 59.14 b
± 4.26 **
Medium
B 68.50 a
± 2.90
B 30.71 b
± 4.71 **
Low
B 63.33 a
± 2.84
B 35.15 b
± 4.69 **
SL ** *
Mean values within the same row bearing different superscripts (small) are significantly different.
Mean values within the same column bearing different superscripts (capital) are significantly different.
SL: Significance level.
*: Significant at p< 0.05.
**: Significant at p<0.01.
3-3-5-4 Sperm cell concentration
Table 3-16 shows the results of the effetcs of level of feeding
lucerne hay and season on sperm cell concentration. During winter, the
rams fed medium level of feeding had significantly (p<0.05) higher
sperms concentration compared to the other levels of feeding. However,
during summer, the rams maintained on low level of feeding had
significantly (p<0.05) higher sperm concentration compared to the other
levels. With all levels of feeding, the sperm concentration was lower
during summer compared to the respective values of winter; however, the
decrease was highly significant (p<0.001) in rams maintained on medium
level of feeding.
3-3-5-5 Incidence of live sperm
Table 3-17 shows the results of the effect of level of feeding
lucerne hay and season on live sperm percent. During summer, the value
of live sperm percent was significantly (p<0.05) lower with medium level
of feeding. For each level of feeding, the rams maintained lower live
sperm percent during summer compared to the respective winter value ;
but this change was just significant (p<0.05) with medium plane of
feeding
3-3-5-6 Incidence of abnormal sperm
Table 3-18 shows the results of the effect of level of feeding lucerne hay and season on abnormal sperm percent. During summer, the abnormal sperm percent was significantly (p<0.05) higher with low level of feeding. However, during winter, the level of feeding did not influence the abnormal sperm percent significantly. With all levels of feeding, the abnormal sperm percent was higher during summer. This change was significant with high and medium level of feeding (p<0.05) and low level
of feeding (p<0.001).
Table 3.16 Effects of level of feeding lucerne hay and season on sperm cell
concentration (× 109/ml) in Desert rams.
(n = 30, mean ± S.E.M.).
Season Level of feeding
Winter Summer
SL
High
B 2.07 a
± 0.133
AB 1.64 a
± 0.21 NS
Medium
A 2.37 a
± 0.15
B 1.24 b
± 0.13 ***
Low B 2.15 a A 1.80 b NS
± 0.21 ± 0.21
SL * *
Mean values within the same row bearing different superscripts (small) are significantly different.
Mean values within the same column bearing different superscripts (capital) are significantly different.
SL: Significance level.
*: Significant at p<0.05.
***: Significant at p< 0.001.
NS: Not significant.
Table 3.17 Effects of level of feeding lucerne hay and season on the incidence of live sperm (%) in Desert rams.
(n = 30, mean ± S.E.M.).
Season Level of feeding
Winter Summer
SL
High A94.80 a A 93.24 a NS
± 1.37 ± 3.40
Medium
A94.97 a
± 0.82
B 87.60 b
± 3.37 *
Low
A94.55 a
± 1.00
A 91.28 a
± 2.14 NS
SL NS *
Mean values within the same row bearing different superscripts (small) are significantly different.
Mean values within the same column bearing different superscripts (capital) are not significantly different.
SL: Significance level.
*: Significant at p<0.05.
NS: Not significant.
Table3.18 Effects of level of feeding lucerne hay and season on the incidence of
abnormal sperm (%) in Desert rams.
(n = 30, mean ± S.E.M.).
Season Level of feeding
Winter Summer
SL
High
A 3.18 b
± 0.60
B 13.07 a
± 4.07 *
Medium
A 5.45 b
± 1.22
B 13.36 a
± 3.29 *
Low
A 3.86 b
± 1.11
A 21.18 a
± 4.03 ***
SL NS *
Mean values within the same row bearing different superscripts (small) are significantly different.
Mean values within the same column bearing different superscripts (capital) are significantly different.
SL: Significance level.
*: Significant at p< 0.05.
***: Significant at p< 0.001.
NS: Not significant.
3.4. Discussion
This experiment aimed to investigate the effects of restriction of
lucerne hay intake and seasonal changes in thermal environment under
tropical conditions on the mean body weight,scrotal circumference,
thermoregulation, blood metabolites and seminal traits of Desert rams.
The results obtained in this study indicate that the physiological responses
and reproductive performance of Desert rams could be modulated by the
essential experimental treatments imposed, the plane of nutrition and
thermal environment.
3.4.1. Body weight (BW )and scrotum circumference (SC)
The results indicate that restriction of intake of lucerne hay induced
significant change in the mean BW of Desert rams in both seasons (Table
3.3). This response clearly reflected the decrease in nutrient intake
associated with feed restriction. The loss in mean BW during feed
restriction is attributed to loss of body reserves usually associated with
depletion of tissue fat and protein. Davis and Hoppel (1986) indicated
that the BW loss during starvation is related to catabolism of muscle
protein. Henry et al. (2000) reported that feed restriction of Corriedale
ewes resulted in lowering of body fat from 36 to 15 % of BW. The loss in
mean BW of Desert rams reported in the present study could also be
attributed to low intake of dry matter during feed restriction. The loss in
BW reported in feed restricted Sonadi and Dorset Horn cross ewes was
associated with low intake of dry matter (Naqvi and Rai, 1991). Feeding
50-70 % of maintenance level of Merino rams resulted in a decrease in
BW (Parker and Thwaites, 1972). The low mean BW reported in the
current results during feed restriction could also be related to decrease in
availability of protein ingested and consequently insufficient microbial
digestion and food utilization. In Manday and Nellore rams, feeding 9.73
% of protein on dry matter basis resulted in an insufficiency in the
achievement of optimum microbial digestion and efficiency of food
utilization (Mohan et al., 1987). Moreover, the loss in the mean BW
reported during feed restriction of Desert rams could also be associated
with a decrease in total body water. Faichney and Gherardi (1986) noted
that water intake in sheep is positively correlated with food intake. Henry
et al. (2000) reported that restriction of lucerne hay intake in Corriedale
ewes was associated with lowering in BW; the authors attributed this
response to low water intake. A low mean BW was also reported in feed
restricted Finnish Landrace and Dorset Horn cross (Alkass et al, 1982),
Merino (Sutama and Edey 1985) and Scottish Black Face and Cheviot
Welsh cross (Wiener et al., 1988) rams.
The significantly higher mean BW observed in all the experimental
groups of rams during winter compared to respective summer values is
closely associated with increase in food consumption and utilization.
Lincoln et al. (2001) suggested a central regulation of long-term cycles in
voluntary food intake. The authors reported that in Soay rams , voluntary
food intake and body weight increased in cold environment; the authors
attributed this response to increase in blood concentration of alpha-
melanocyte stimulating hormone (Alpha-MSH) which is a positive
stimulator of food intake (Henry et al., 2000).
In the current results, the high rate of mean BW loss observed
during summer compared to winter could be attributed to low food intake
at high environmental temperature (Table 3.2). McDonald et al. (2002)
indicated that in sheep, food intake and protein digestion were lower
under high environmental temperature. In Rambouillet ewes, the
reduction in food intake observed at high ambient temperature was
apparently attributed to depression of appetite centre (Moose et al.,
1969). Bhattacharya and Hussain (1974) reported that the food intake and
protein digestibility decreased in Awassi wethers in response to high
environmental temperature and consequently the BW was reduced. El
noutly et al. (1988) observed a significant reduction in dry matter intake
(DMI) in Egyptian Barki and Rahmani ewes during summer compared to
spring and winter; this was attributed to the effects of heat stress.
The current results indicated that feed restriction significantly
reduced the scrotal circumference (SC) of Desert rams in both seasons
(Table 3.4). This response is attributed to general loss in the mean BW
and loss of subcutaneous fat in the scrotal sac. In Merino rams, the SC
was positively correlated with BW (Foster et al., 1989; Murray et al.,
1990 b). In Booroola and Merino rams supplemented with high lupin
grain, a significant correlation between BW and testicular volume was
reported by Martin et al. (1987). Furthermore, Alkass et al. (1982) also
reported lower SC in feed restricted Scottish Black Face and Finnish
Landrace Dorset Horn cross rams.
The higher SC reported during winter for both high and medium
levels of feeding compared to respective summer values could be
attributed to the increase in number of seminiferous tubules and
spermatogenic activity during winter. Foster et al. (1989) and Kealy
(2004) indicated that the SC could be adopted as an index of testicular
weight and ram fertility. In mature Sudanese Hamari rams, Alsayed
(1996) reported relatively higher values of SC during winter
conditions.Islam and Land (1977) reported higher SC values of Finnish
Landrace and Tasmanian rams in temperate zone during the cold season.
3.4.2. Thermoregulation
In this experiment, the rams have been exposed to marked changes
in their thermal environment. The extremes of ambient temperature and
relative humidity reported during winter and summer modulated the
physiological responses of rams to restriction of intake of luceme hay.
The data indicate that reducing the level of feeding influenced the
thermoregulatory response of Desert rams. During both seasons, the rams
exhibited significantly lower rectal temperature (Tr) with low level of
feeding in the morning (Table 3.5) and afternoon (Table 3.6). This
response is clearly associated with a decrease in metabolic heat
production. Previous studies in sheep have reported a decrease in
metabolic heat production in response to feed restriction (Blaxter, 1962;
Graham, 1964; Freetly et al., 2002). Ahmed and Abdelatif (1992)
reported low Tr values in the morning and afternoon in feed restricted
Desert rams under wet summer tropical conditions. The present findings
in Desert rams are in agreement with the results reported by Naqvi and
Rai (1991) in feed restricted Sonadi and Dorset Horn cross ewes.
The significantly higher Tr values obtained in the afternoon during
summer compared to winter values is clearly related to the increase in the
thermal load with rise in ambient temperature during the day. A high
correlation between ambient temperature and Tr was reported during
summer in Egyptian Barki and Rahmani ewes (El nouty et al., 1988)
compared to spring and winter values.
The current results indicate that the diurnal change in Tr observed
in all experimental groups in both seasons (Table 3.7) is associated with
the circadian changes in thermal environment. Also this diurnal change
could be attributed to the higher values of Tr reported in all groups of
rams during summer compared to winter. Piccione and Caola (2003)
indicated that the circadian rhythm of body temperature reflects the
adaptation of animals to changes in external environmental temperature.
In the current study, the diurnal change in Tr of Desert rams was more
pronounced with the low plane of nutrition irrespective of the season.
This response could be related to low metabolic rate of feed restricted
rams associated with low heat production. However, in the current
results, the mean diurnal change in ambient temperature reported during
the experimental period was 15.75ºC during winter and 12.66ºC during
summer. This change in ambient temperature influenced body
temperature of the experimental animals.
Da silva and Minomo (1995) indicated that limited diurnal changes in Tr
of Corriedale rams in the tropics during summer (0.42ºC) and winter
(0.46ºC) were closely related to the prevailing ambient temperature
The data indicate that feed restriction was associated with a
significant decrease in respiration rate (RR) of Desert rams during
summer (Table 3.8).This response is accounted for by a general decline in
metabolism and heat production. The low food intake in rams could have
been associated with a low metabolic rate. Ahmed and Abdelatif (1992)
reported a significant decline in morning values of RR of feed restricted
Hamari rams. Feed restriction of Sonadi and Dorset Horn Cross ewes
decreased the morning values of RR compared to the control (Naqvi and
Rai, 1991).
The significantly higher values of RR observed at 7:00 a.m.
during summer compared to the respective winter values with all levels of
feeding is a recognized response of sheep to the high thermal load during
summer day. Similarly, higher morning RR value was previously
reported during summer under subtropical conditions in Egyptian Barki
and Rahmani ewes (El nouty et al., 1988).
The current results indicated that in both seasons feed restriction
induced decreases in Tr and RR values of Desert rams. It could be
concluded that thermoregulation of Desert rams was influenced by feed
restriction and seasonal changes in thermal environment.
3.4.3. Blood metabolites
The observations made in the present study indicate that the
concentrations of blood metabolites were influenced by the level of
feeding lucerne hay and the thermal environment of the animals. The
rams maintained on low level of feeding showed significantly lower
values of serum total protein concentration during winter compared to
summer values (Table 3.9). Swenson (1993) indicated that the synthesis
of plasma proteins is markedly reduced in prolonged dietary deficiency
when the supply of amino acids for digestive process is not adequate. In
feed restricted Merino rams, Setchell et al. (1965) reported low levels of
total plasma protein. The current results confirm the findings reported
previously by Ahmed and Abdelatif (1992) in Desert rams fed 68% of
their ad libitum level of luceme hay intake. Naqvi and Hooda (1991)
observed lower serum protein concentration in Malpura and cross
Avikalin non-pregnant ewes fed 30% of ad libitum intake of hay and
concentrate ration
In the present study, the significantly lower serum albumin concentration obtained with feed restriction in both seasons in Desert rams (Table 3.10) is clearly associated with
the low amount of lucerne hay consumed and consequently the amount of protein intake. The current results are
consistent with the findings of Ahmed and Abdelatif (1992) who reported a reduction in plasma albumin level in Desert rams during feed restriction under wet summer conditions. The results have shown that with all levels of feeding,
the serum albumin level was lower during summer compared to winter values. This finding could be related to the low intake of lucerne hay during summer compared to
winter. The response could also be associated with an increase in water consumption during summer and
development of haemodilution. However, in Sudanese Desert ewes, the serum albumin level was not influenced by
seasonal changes in thermal load (Alsayed, 1997). In the current study, the serum urea level was
significantly higher during summer compared to winter values in rams fed low level of lucerne hay (Table 3.11). This
response could be related to low water intake. Previous studies have reported a positive correlation between water
intake and dry matter intake in sheep (Kamphus, 2000) and a decrease in urinary nitrogen excretion during water
restriction (Aganga, 1992). Furthermore, the restriction of food intake could have been associated with recycling of
urea and reduction in urinary excretion. Bunting et al. (1992) reported an inverse relationship between the level of
protein intake and the amount of blood urea nitrogen entering the rumen. Also Farid (1985) attributed reduction
in urinary nitrogen excretion in Barki rams fed 60% of their maintenance requirement to improved utilization of digested
nitrogen. Conversely low plasma urea levels in response to food restriction have been reported in Desert rams (Ahmed
and Abdelatif, 1992) and Sonadi and Dorset Horn cross rams (Naqvi and Rai, 1991). However, Herny et al. (2000) noted that feed restriction had no significant influence on
plasma urea level in ovariectomized Corriedale ewes. In the present study, in both seasons, the plasma
glucose level was decreased slightly with lowering of the level of intake of lucerne hay (Table 3.12). This response
could be attributed to decrease in availability of nutrients and lower rate of production of propionate which is known
to be the main precursor of glucose in ruminants (Bergman, 1973,1990; Trenkle, 1981;). The low plasma glucose level
obtained in feed restricted rams could also be attributed to the low amount of protein intake as a proportion of glucose is derived from amino acids by gluconeogenesis (Reilly and
Ford, 1971). This response confirms previous reports in Desert rams (Abdelatif and Ahmed, 1992), Sonadi and Horn
Cross rams (Naqvi and Rai, 1991) and Malpura and cross Avikalin non- pregnant ewes (Naqvi and Hooda, 1991).
Hypoglycaeamia was also reported in Suffolk wethers fed on submaintenance energy allowance (Moloney and Moore,
1994). 3.4.4. Semen characteristics
The current results suggest that the seminal traits in Desert rams were influenced by lowering of the plane of
nutrition and seasonal changes in the thermal environment. In most mammals, the process of spermatogenesis and
Sertoli cell multiplication are influenced by seasonal changes of environmental temperature through the central nervous
system (Hotzel et al., 2003). In temperate breeds of rams, Smith et al. (1999) reported seasonal change in the total
protein concentration of seminal plasma, with higher levels obtained during the breeding season. For Desert rams,
previous studies indicated seasonal effect on their reproductive performance and seminal traits (Galil and
Galil, 1982 a,b; Alsayed, 1996) with decline in semen quality during summer accounted for by thermal influence.
The current study is unique in that it investigated the interaction between the plane of nutrition and seasonal
change in thermal environment on seminal traits of Desert rams. This approach is rather realistic as it attempts to
simulate the nutritional and climatic stresses experienced by animals under natural tropical conditions.
The ejaculate volume was significantly lower with the low level of feeding in both seasons (Table 3.13). This
response is apparently associated with the influence of low plane of nutrition on endocrine response in rams. Brown
(1994) indicated that during feed restriction of Merino rams, low concentration of luteinizing hormone (LH) resulted in
reduction of testosterone secretion. The low ejaculate volume of food restricted rams could be attributed to
decrease in the function of pituitary gland and testes Alkass et al. (1982) reported a decrease in the size of pituitary gland
and testes in feed restricted rams. Consequently, the concentration of LH and its action on Leydig cells to release
testosterone is reduced. A low testosterone level is usually associated with reduction in testicular, epididymal and accessory genital glands secretions which contribute to
seminal fluid. The low ejaculate volume obtained with low level of feeding could be related mainly to a decrease in the
accessory genital glands, secretions associated with endocrine changes. The androgen dependent seminal
vesicles contribute 50% of the seminal plasma volume in ruminants (Jainudeen and Hafez, 2000).
In the tropic, the day length is shorter during winter compared to summer. However, it is unlikely that
photoperiodism has influenced the observed seasonal changes in the ejaculate volume of Desert rams. The
significantly higher ejaculate volume observed during winter with all levels of feeding could be related to stimulatory
effects of testosterone. Kajihera et al.(1972) indicated that the reproductive endocrine response in mammals involves activation of the pituitary gland and consequent activation
of the accessory genital glands by testosterone under the control of LH. Seasonal changes in testosterone secretion
and ejaculate volume were reported in Hampshire rams in temperate environment (Purvis et al., 1974) and in Finn
cross rams under subtropical conditions (Amir and Volcani, 1965b). The high ejaculate volume of Desert rams reported
in winter in the current study is likely to be related to the effects of exposure to cold environment associated with
endocrine activation. The current findings are in agreement with the observations made by Galil and Galil (1982a) and
Alsayed (1996) in Desert rams, reporting high ejaculate volumes during winter. However, the high volumes of
ejaculates obtained could be related to breed characteristic. Alsayed (1996) reported an ejaculate volume of 2.2ml in
Hamari Desert rams. In the present study, the sperm mass motility (MM)
was significantly lower with feed restriction during summer (Table 3.14). This is clearly related to decline in the
nutritional status of the rams. Howland (1975) noted that the seminal plasma metabolites are drawn from blood
metabolites. Amir and Volcani (1965a) indicated that the fructose level in seminal plasma is an indicator of the nutritional status of Awassi rams. Moule et al. (1996)
reported low fructose concentration in ejaculates of Merino
and Romney Marsh rams fed 30% of energy intake. In the current study, the low food intake during summer could
have induced low fructose level in seminal plasma and consequently decreased mass motility of spermatozoa.
However, Galil and Galil (1982b) reported a low level of fructose in seminal plasma of Desert rams during summer
and attributed this to high ambient temperature and reduced secretion of testosterone hormone. Chahal et al. (1979) indicated that during summer, fructose level and
sperm MM were positively related and reduced sperm motility could be related to low metabolic rate of
spermatozoa. The authors also indicated that the reduction in fructose level could be related to the reduction in seminal
vesicles, activity in response to low blood levels of LH and testosterone. The reduction in sperm MM could also be
partly associated with the low serum albumin concentration reported in the current study in feed restricted rams.
Miyamoto and Chang (1973) suggested that serum albumin is the best medium for increasing the proportion of motile
sperms in vitro with increased capacitation and fertilization. Smith et al. (1999) noted a poor maintenance of sperm
motility in rams with low seminal plasma proteins. The low sperm MM observed in the current study could be
associated with the low fructose level in feed restricted rams as well as albumin concentration.
The significantly lower sperm mass motility (MM) observed with all levels of feeding during summer compared
to winter (Table 3.14) could be related to exposure of the testes and epididymal sperm reserve to high ambient
temperature. Also the low sperm MM could be related to the high body temperature of rams reported in the current
results during summer compared to winter (Table 3.6). In Desert rams, Galil and Galil (1982a) reported a decrease in
sperm MM during summer compared to winter. The results have shown that in both seasons, the
medium and low level of feeding were associated with a significant reduction in sperm individual motility IM (Table
3.15). The low IM value could be attributed mainly to low plane of nutrition and protein intake. Also it could be
related to relatively low concentration of seminal plasma metabolites accompanied by thermal stress during summer. Pratt and Wettemann (1986) noted that the activity of thyroid gland in sheep was depressed during heat stress. In
thyroidectomized Merino rams Chandraseckhar et al. (1986) related low sperm IM to a decline in sex hormone binding
globulins. The progressive motility which is acquired in the epididymis involves activation of a unique protein called
CatSper, which is localized to the principal piece of the sperm tail. This protein appears to be Ca+2 ions channel that
permits cAMP-generalized Ca+2 influx (Ganong, 2003).The reduction is sperm IM could also be associated with low
activity of pituitary gland under feed restriction conditions. In Merino and English Leicester rams, food restriction was
associated with low weights and secretions of seminal vesicles which are controlled by LH secretion (Setchell et al.,
1965). The authors also reported low seminal plasma fructose concentration and a decline in sperm IM.
Therefore, the low sperm IM observed in Desert rams in the current study is likely to be related to low blood metabolites
observed and the depressed activity of endocrine glands in response to feed restriction. However, during summer,
thermal stress had a role in lowering IM.
The results indicate that irrespective of the level of feeding, the
sperm IM was significantly higher during winter compared to summer
values (Table 3.15). This finding could be associated with the efficiency
of the cremaster muscle and tunica dartos in the maintenance of testicular
thermoregulation during winter, which provided favourable medium for
sperms to acquire motility during epididymal transit and preservation.
High values of sperm IM were previously reported in Desert rams during
winter and autumn compared to summer (Galil and Galil, 1982a).
The results obtained indicate that the rams had higher sperm
concentration with the medium level of feeding during winter (Table
3.16). This response could be associated with the low ejaculate volume
obtained with low levels of feeding compared with the high level group,
and the fact that ejaculate volume depends primarily upon the secretion of
seminal plasma rather than sperm concentration (Howland, 1975).
However, Brown (1994) noted that the influences of nutrition on
reproductive process in rams are mediated via effects of dietary
constituents on the hypothamic- pituitary axis. The author also indicated
that the nutritional regime can alter androgen activity without necessarily
affecting spermatogenesis as certain constituents of the diet can
differently affect the production of and /or the release of LH and FSH.
However, the low sperm concentration reported during summer with the
medium level of feeding could be associated with the increase in ambient
temperature. The present findings regarding sperm cell concentration are
consistent with the results reported previously in feed restricted Merino
rams (Parker and Thwaites, 1972) and Scottish Black Face and Finnish
Landrace cross rams (Alkass et al., 1982).
It is evident that the sperm cell concentration was lower with all levels of feeding during summer compared to
winter (Table 3.16), particularly in rams maintained on medium level of feeding. This observation indicates that the magnitude of change in sperm cell concentra-tion in Desert
rams is influenced by seasonal changes in thermal environment and feed restriction. This could be related to a decrease in spermatogenic activity and epididymal reserve during the hot season due to spermatogenic degeneration.
Similarly a lower sperm concentration was reported in Desert rams during summer compared with winter values
(Galil and Galil, 1982a). In the current study, lower live sperm values were
obtained during summer compared to winter values,
particularly in the group of rams maintained on medium level of feeding (Table 3.17). This response could be related to the increase in body temperature resulting in increase in metabolic activity of testicular cells leading to hypoxia and
disturbance of spermatogenesis. Chahal et al. (1979) reported low live sperms percent in Corriedale rams during
summer and attributed this to testicular hypoxia which probably plays a role in heat-induced spermatogenic disturbance. In Desert rams, Galil and Galil (1982a)
reported low live sperms percent during summer. However, reduction in live sperm percent in association with feed
restriction could be attributed to the reduction in number of seminiferous tubules and increase in dead sperm percent
due to increase in degenerative process. Feed restriction increased significantly the incidence of abnormal
sperms during summer (Table 3.18). This response is associated with a
decrease in availability and supply of essential nutrients required for
sperm production in the testis and epididymal maturation accompanied
with thermal stress during summer. Setchell et al. (1965) reported low
nutrient supply of testicular and epididymal tissues in feed restricted
Merino and English Leicester rams. Feed restriction has also an androgen
dependant effect on sperm maturation during epididymal transit resulting
in immature sperm of protoplasmic droplet (Chardraseckhar et al. 1985).
Feed restriction of Merino rams increased abnormal sperm percent
(Sutama and Edey, 1985), while severe feed restriction resulted in
permanent damage to gonadal tissues of Merino rams (Brown, 1994).
Young et al. (2000) reported apoptotic testicular degeneration in feed
restricted mice.
The current results indicate that with all levels of feeding, the
abnormal sperm percent was higher during summer compared to winter
values (Table 3.18). This could be accounted for by the high body
temperature reported in this study during summer and the impairment of
thermoregulation capacity of the scrotum in the hot environment. Sailer
et al. (1997) indicated that in mammals, testicular hyperthermia disturbed
spermatogenesis. The authors also indicated that epididymal sperms are
susceptible to acid induced DNA denaturation and minor chromatin
abnormalities.However, Lue et al. (2002) noted that testicular
hyperthermia in rats induces stage specific and germ cell–specific
apoptosis, azoospermia and oligospermia. Other studies have reported
that increased testicular temperature provokes testicular degeneration and
increases the percent of abnormal sperms (Mieusset et al., 1991;
Mieusset et al., 1992; Kastelic et al., 1997; Love and Kenney, 1999;
Kastelic et al., 2000; Ibrahim et al., 2001). The testicular degenerations
observed during summer in temperate breeds of rams are associated with
seasonal sterility of rams. Karagiannidis et al. (2000) reported high
percent of abnormal sperms of Friesian and Chios rams during the hot
season in the suptropics. However, in the tropics, thermal stress rather
than seasonal changes has detrimental effect on sperm abnormalities.
Galil and Galil (1982) reported high abnormal sperm percent in Desert
rams during summer. It could be concluded that regardless of the
nutritional status of Desert rams, summer heat increased the percentage of
abnormal sperms.
3.5. Summary
1. Nine entire Desert rams were used to study the effects of the level
of feeding lucerne hay (high,medium and low) and season (winter
versus summer) on mean body weight (BW), scrotal
circumference (SC), thermoregulation, blood metabolites and
seminal traits.
2. The mean BW of rams was significantly lower in feed restricted
rams in both seasons. For all the experimental animals, the mean
BW was significantly higher during winter compared to summer
values.
3. The SC of rams maintained on low level of feeding was
significantly lower regardless of season.
4. The rectal temperature (Tr) was lower in feed restricted rams in
the morning and afternoon in both seasons. During summer, Tr
values in the afternoon were significantly higher compared to
respective winter values; there were significant diurnal changes in
Tr in both seasons.
5. During summer, at 7: 00 a.m. the respiration rate (RR) was
significantly lower with the low level of feeding.
6. The serum total protein level was significantly lower in feed
restricted rams during winter compared to the control group. The
serum albumin level decreased significantly with feed restriction
during both seasons. All the experimental groups had lower serum
albumin concentration during summer compared to winter
values.The rams maintained on low level of feeding had higher
serum urea concentration during summer compared to winter.
7. The ejaculate volume was significantly lower with low level of
feeding during both seasons. All the experimental animals
showed a significantly lower ejaculate volume during summer
compared to winter.
8. The sperm mass motility (MM) was significantly lower with low
level of feeding during summer. All the experimental animal
showed a significantly higher sperm MM during winter compared
to summer values.
9. The sperm individual motility (IM) was significantly lower in
rams maintained on low level of feeding regardless of season. The
sperm IM was significantly lower during summer compared to
winter values , irrespective of the level of feeding .
10. The sperm cell concentration was significantly higher with feed
restriction in both seasons. With medium level of feeding, it was
significantly lower during summer compared to winter value.
11. The live sperm percent was significantly lower during summer
with the medium level of feeding compared to the respective
groups, values. Also the medium level group had significantly
lower live sperm percent during summer compared to winter
values.
12. The abnormal sperm percent was significantly higher with low
level of feeding compared to the higher level of feeding. During
summer, the abnormal sperm percent was significantly higher
with all levels of feeding compared to values obtained during
winter.
CHAPTER FOUR EFFECTS OF EXPOSURE TO SOLAR RADIATION ON
THERMOREGULATION, BLOOD COMPOSITION AND SEMEN
CHARACTERISTCS 4.1 Introduction
In the tropical environment, solar radiation constitutes a critical factor in the
animal’s energy budget (Mitchell, 1977). High intensity of solar radiation during the
day and reradiation from the surroundings during the night produce fluctuations in
thermal environment and animal body temperature (Mount, 1979). The solar cycle has
marked consequences for the climatic environment and animals have adapted to use
temperature and photoperiod as hints to trigger reproductive activity (Haynes and
Howles, 1981).
The range of environmental conditions under which sheep are kept for
production is extremely wide. The thermal environment influences the utilization of
food, energy requirements and the physiological means by which sheep can adjust
their metabolism (Graham et al., 1959).When sheep are moved to a new thermal
environment, adjustments of their heat loss mechanisms occur.In a considerably
higher environmental temperature, the body temperature increases and heat stress
develops when the total heat gain exceeds the heat loss capabilities of sheep (Hahn
and Becker, 1984). Sheep adjust their physiological means of heat disposal mainly by
the evaporative cooling mechanisms to maintain their deep body temperature
(McArthur, 1980 ;Da Silva et al. 2002). In severe thermal stress, sheep react by
reducing food intake, increasing water intake (Terrill, 1968; Robertshaw, 1981) and
reducing faecal and urinary water loss (Macfarlane, 1981).
In all domestic mammals, spermatogenesis is depressed at body temperature
and male gametes fail to tolerate the increase in body temperature(Arthur et al.,
1985).Extremely high environmental temperature has an immediate effect on
spermatogenesis, in contrast to moderately high environmental temperature extending
over several months, which show a delayed effect (Jainudeen and Hafez, 2000).
In the tropics, under the nomadic system of sheep rearing, heat stress affects
the physiological responses and productive abilities (Johnson, 1987). Under this
extensive system, the reproductive performance of rams is influenced by thermal load
(Yeates et al., 1975b; Kastelic et. al ,1997), as they have to combat heat and serve
females throughout the year. Accordingly, the purpose of this experiment was, firstly,
to investigate the effects of exposure to direct solar radiation on the physiological
responses and semen characteristics in Desert rams. The second objective was to
asses the effect of exposure to solar heat load on the responses of rams to the
frequency of ejaculation of semen.
4.2 Experimental procedure
The experimental plan is presented in Table 4-1 .Eight entire Desert rams were
randomly assigned to two groups of 4 rams each. Group A was kept under shade
(shaded), and group B was exposed to direct solar radiation (unshaded). Both groups
of rams were allowed an adaptation period of 2 weeks, followed by 5 weeks of
experimental period. Throughout the adaptation and experimental periods, the
animals were fed chopped lucerne hay and were given tap water ad libitum.
During the first three weeks of experimental period, for both shaded and
unshaded groups of rams, the measurements of rectal temperature (Tr) and respiration
rate (RR) were carried out twice daily, at 7:00 a.m. and 2:00 p.m. During this period,
blood and semen samples were collected weekly
Table 4.1 Experimental plan
Experimental
period
Experimental
groups
Daily
measurements
Weekly
sampling Measurements
The first 3 weeks
(25Oct.-15 Nov.)
Shaded (A)
Unshaded (B)
Tr: (7:00 a.m.
2:00 p.m).
RR: (7:00 a.m.
2:00 p.m).
Daily Sampling
-Blood
- Semen
-Scrotal
circumference
-Blood
composition
-Semen
characteristics
The last week
(22-28 Nov.)
A and B
alternatively
Semen samples
for 3 consecutive
days
Blood samples
before the first
collection of
semen and after
the last one
-Blood
composition
-Semen
characteristics
at 8:00 a.m. The measurement of scrotal circumference was also performed weekly.
In the 4th and 5th week of experimental period, the exhaustion test was
performed for both groups of rams alternatively. In this treatment, semen samples
were collected every 30 min. from each ram in three consecutive days. During the
exhaustion test, for each ram, blood samples were drawn before the collection of the
first semen sample and after the last one. The unshaded group was represented by 3
rams only during the exhustion test due to the sudden death of one ram.
In the first day of exhaustion test, in the control group, all rams ejaculated and
2 rams ejaculated up to 6 collections. However, on the second day, one ram failed to
ejaculate, and up to 5 collections were obtained from two rams. In the third day, two
rams ejaculated up to 6 collections; however, one ram failed to ejaculate. For the
unshaded rams, on the first day all the rams ejaculated and 2 rams ejaculated up to 5
collections. On the second day, all the rams ejaculated and one ram ejaculated up to 6
collections. However, in the third day one ram failed to ejaculate, and up to 4
collections were obtained from 2 rams.
Blood samples were used for the determination of the PCV and leukocytic
indices. Serum samples were used to determine the concentrations of total protein,
albumin and urea, and plasma samples were used for the measurement of glucose
concentration. The semen samples were used for the determination of ejaculate
volume, and the analysis of mass and individual motility, sperm concentration, live
and abnormal sperms percent and semen pH.
4.3. Results
The effects of exposure to solar radiation on thermoregulation, blood
composition and semen characteristics and the effects of exposure to solar radiation
and exhaustion test on blood composition and semen characteristics were investigated
in Desert rams. The results obtained are presented as mean ± S.E.M.
The data for the prevailing climatic conditions during the experimental period
are shown in Table 4.2.
4.3.1. Effects of exposure to solar radiation
4.3.1.1. Thermoregulation
4.3.1.1.1. Rectal temperature (Tr)
Table 4.3 shows the results of the effect of exposure to solar radiation on the
mean values of rectal temperature (Tr) of rams measured at 7:00 a.m. In both groups
of rams, Tr increased in the last two weeks of the experimental period. The Tr value
measured in the second week for the unshaded rams was significantly (p<0.05)
higher. However, compared to the shaded rams, Tr was slightly higher in the
unshaded group of rams during the experimental period .
Table 4.4 shows the results of the effect of exposure to solar radiation on Tr
measured at 2.00 p.m. In the shaded group, Tr decreased slightly in the second week
and maintained the initial level in the third week. The group of rams exposed to solar
radiation had a significantly (p<0.05) higher Tr value in the first week compared to
values obtained in weeks 2 and 3. The rams exposed to solar radiation had
significantly
Table 4.2 The prevailing climatic conditions during the experimental
period (25 October – 28 November /2000).
Temperature (ºC) Time
(weeks) Max. Min. Mean
RH (%)
(Mean)
1 35.6 19.7 27.7 23
2 38.5 20.6 29.6 25
3 36.5 20.2 28.4 26
4 32.9 18.0 25.5 39
5 34.2 15.9 25.1 30
Mean
± SE
35.15
±1.40
18.9
±1.7
27.26
±1.72
28.6
±5.68
Solar radiation: 377 W/m2
Table 4.3 Effect of exposure to solar radiation on rectal temperature, Tr (ºC)
of Desert rams at 7: 00 a.m.
(n = 12, mean ± S.E.M.).
Time
(weeks) Shaded Unshaded SL
1
A 38.18 a
± 0.29
B 38.25 a
± 0.39
NS
2 A 38.48 a
± 0.10
A 38.95 a
± 0.30 NS
3 A 38.48 a
± 0.06
B 38.88 a
± 0.11 NS
SL NS *
Mean values within the same row bearing similar superscripts (small) are not
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL : Significance level.
* : Significant at p < 0.05.
NS: Not significant
Table 4.4 Effect of exposure to solar radiation on rectal temperature, Tr (ºC)
of Desert rams at 2: 00 p.m.
(n = 12, mean ± S.E.M.).
Time
(weeks) Shaded Unshaded SL
1
38.80 b
± 0.10
A 39.98 a
± 0.27
***
2
A 39.28 a
± 0.19
B 39.68 a
± 0.23 NS
3
A 38.83 a
± 0.11
B 39.30 a
± 0.40 NS
SL NS *
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL : Significance level.
* : Significant at p < 0.05.
*** : Significant at p< 0.001.
NS: Not significant.
(p<0.001) higher Tr compared to the shaded group only in the first week. Both
groups of rams showed a diurnal pattern in Tr which was more pronounced in animals
exposed to solar radiation.
4.3.1.1.2 Respiration rate (RR)
Table 4.5 shows the results of the effect of exposure to solar radiation on RR
at 7:00 a.m. In the shaded groups of rams, RR was significantly (p<0.05) higher in the
second week compared to values obtained in the first and third week. However, in the
unshaded rams, RR was significantly (p<0.05) higher in the last two weeks
compared to the value obtained for the first week. The rams exposed to solar
radiation maintained significantly higher RR values compared to the control in the
first and second week (p< 0.05) and in the third week (p< 0.01).
Table 4-6 shows the results of the effects of exposure to solar radiation on RR
at 2.00 p.m. In both groups of rams, RR tended to increase progressively during the
experimental period. The change in RR was significant for the shaded (p<0.05) and
unshaded (p<0.01) group of rams. The unshaded group of rams maintained
significantly higher values of RR compared to the shaded group in the first week
(p<0.001) and in the second and third week (p<0.01). The changes in RR in both
groups showed a diurnal pattern which was more pronounced in the unshaded group
of rams.
4.3.1.2 Blood composition
4.3.1.2.1 Packed cell volume (PCV)
Table 4.7 shows the results of the effects of exposure to solar radiation on
PCV level. In both groups of rams, there was no significant changes in PCV level
during the experimental period. Also the results did not reveal any significant effect of
exposure to solar radiation on PCV
Table 4.5 Effect of exposure to solar radiation on respiration rate, RR (breaths/min)
of Desert rams at 7: 00 a.m.
(n = 12 , mean ± S.E.M.).
Time
(weeks) Shaded Unshaded SL
1
B 22.15 b
± 0.29
B 24.42 a
± 1.12
*
2
A 26.20 b
± 0.97
A 29.28 a
± 0.69 *
3
B 23.83 b
± 0.91
A 28.50 a
± 1.54 **
SL * *
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL : Significance level.
* : Significant at p < 0.05.
** : Significant at p <0.01.
Table 4.6 Effect of exposure to solar radiation on respiration rate, RR(breaths/min)
of Desert rams at 2: 00 p.m..
( n = 12 ,mean± S.E.M.).
Time
(weeks) Shaded Unshaded SL
1
B32.98 b
± 1.55
B78.30 a
± 7.03
***
2
AB57.73 b
± 5.89
A 109.78 a
± 9.17 **
3
A71.75 b
± 0.85
A108.55 a
± 8.82 **
SL * **
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL : Significance level.
* : Significant at p < 0.05.
** : Significant at p < 0.01.
*** : Significant at p < 0.001.
Table 4.7 Effects of exposure to solar radiation on the PCV (%) in Desert rams.
(n = 12 , mean ±S.E.M.).
Time
(weeks) Shaded Unshaded SL
1
A26.75 a
± 1.31
A26.75 a
± 1.25
NS
2
A24.00 a
± 0.71
A22.25 a
± 1.65 NS
3
A27.00 a
± 1.58
A23.00 a
± 2.27 NS
SL NS NS
Mean values within the same row and column bearing similar superscripts are
not significantly different.
SL : Significance level.
NS: Not significant
level. However, during the second and third week of the experimental period, the
rams exposed to solar radiation maintained lower values of PCV.
4.3.1.2.2 Leukocytic indices
Table 4.8 shows the results of the effects of exposure to solar radiation on total
leukocyte count (TLC). For both groups, there was no significant change in TLC
during the experimental period. Also the exposure to solar radiation did not elicit any
significant effect on TLC.
Table 4.9 shows the results of the effect of exposure to solar radiation on the
differential leukocyte count (DLC). For lymphocytes, there was no significant change
during the experimental period for the shaded and unshaded group of rams. Also the
exposure to solar radiation was not associated with a significant change in the ratio of
lymphocytes.
There was no significant change in the ratio of neutrophils in the shaded group
of rams. However, in the unshaded group, the ratio of neutrophils was significantly
(p< 0.05) higher in the first week of exposure to solar radiation compared to the
values obtained in the second and third week. There was no significant difference in
the ratio of neutrophils between the shaded and unshaded rams.
For each group of rams, there was no significant change in the ratio of
eosinophils during the experimental period. However, for the shaded group of rams,
there was an increase in the ratio of eosinophils in the third week and for the unshaded
group, there was a slight decrease. The exposure to solar radiation did not affect the
ratio of eosinophils in the first and second week; in the third week, the unshaded
group had significantly (p<0.05) lower ratio of eosinophils compared to the shaded
group.
Table 4.8 Effect of exposure to solar radiation on total leukocyte count,
TLC (×103/µl) in Desert rams.
(n = 12, mean± S.E.M.).
Time
(weeks) Shaded Unshaded SL
1
A5.86 a
A5.88 a NS
± 0.30 ± 0.66
2
A6.15 a
± 0.45
A7.54 a
± 0.61 NS
3
A8.08 a
± 0.15
A7.64 a
± 0.90 NS
SL NS NS
Mean values within the same row and column bearing similar superscripts are
not significantly different.
SL: Significance level.
NS: Not significant.
Table 4.9 Effect of exposure to solar radiation on differential leukocyte count ,
DLC in Desert rams.
(n = 12 , mean± S.E.M.).
Cell type
(%)
Time
(weeks) Shaded Unshaded SL
1
A 56.25 a
± 4.21
A 52.75 a
± 5.39
NS
2 A 64.50 a
± 2.02
A 55.75
± 6.61 NS
3 A 61.75 a
± 0.63
A 63.75 a ± 1.38
NS
Lymphocytes
SL NS NS
1 A 37.00 a
± 4.45
A 41.05 a ± 5.73
NS
2 A 28.75 a
± 1.97
B 29.76 a
± 0.63 NS
3 A 28.75 a
± 1.25
B 29.00 a ± 1.47
NS
Neutrophils
SL NS *
1 A 3.25 a
± 0.48
A 3.50 a
± 0.65 NS
2 A 2.25 a
± 0.63
A 3.00 a
± 0.01 NS
3 A 5.50 a
± 1.55
A 2.25 b ± 0.25
*
Eosinophils
SL NS NS
1 A 3.50 a
± 0.50
B 2.75 a
± 0.48 NS
Monocytes
2 A 4.75 a
± 0.25
A 4.50 a
± 0.50 NS
3 A 3.75 a
± 0.75
A 4.50 a ± 0.50
NS
SL NS *
Mean values within the same row bearing different superscripts (small) are significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
*: Significant at p < 0.05.
NS: Not significant.
In the control group, there was no significant change in the ratio of monocytes during
the experimental period, but in the group exposed to solar radiation, there was a
significant (p< 0.05) increase in the ratio of monocytes in the second and third week
of the experimental period. Exposure to solar radiation did not affect the ratio of
monocytes during the experimental period.
4.3.1.2.3 Serum total protein
Table 4.10 shows the results of the effects of exposure to solar radiation on serum total protein concentration. In the shaded group of rams, the serum total protein level decreased significantly (p< 0.05) in the third week of the experimental period. In the group of rams exposed to solar radiation, there was no significant change in total protein concentration during the experimental period. The exposure to solar radiation increased the total protein concentration significantly (p< 0.05) only in the third week of the experimental period compared to the respective value
obtained for the shaded rams. 4.3.1.2.4 Serum albumin
Table 4.11 shows the results of the effects of solar radiation on serum albumin
concentration. During the experimental period, both groups showed a gradual
insignificant decrease in serum albumin concentration. In the second week, the serum
albumin level was significantly (p< 0.05) lower in the group exposed to solar
radiation compared to the value obtained for the shaded group.
4.3.1.2.5 Serum urea
Table 4.12 shows the results of the effects of solar radiation on serum urea
concentration. In both groups of rams, there was a significant (p< 0.05) decrease in
serum urea level during the experimental period.
Table 4.10 Effect of exposure to solar radiation on serum total protein concentration
(g/dl) in Desert rams.
(n =12, mean ± S.E.M.).
Time
(weeks) Shaded Unshaded SL
1
A7.58 a
± 0.40
A7.30 a
± 0.14
NS
2
A7.53 a
± 0.19
A7.78 a
± 0.36 NS
3
B6.63 b
± 0.25
A7.73 a
± 0.33 *
SL * NS
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital)
are significantly different.
SL : Significance level.
* : Significant at p <0.05.
NS: Not significant .
Table 4.11 Effect of exposure to solar radiation on serum albumin concentration
(g/dl) in Desert rams .
(n = 12, mean± S.E.M.).
Time
(weeks) Shaded Unshaded SL
1
A3.85 a
± 0.40
A3.63 a
± 0.10
NS
2
A3.80 a
± 0.11
A3.50 b
± 0.07 *
3
A3.70 a
± 0.11
A3.48 a
± 0.06 NS
SL NS NS
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing similar superscripts (capital) are
not significantly different.
SL : Significance level.
* : Significant at p < 0.05.
NS: Not significant .
Table 4.12 Effect of exposure to solar radiation on serum urea concentration
(mg/dl) in Desert rams .
(n = 12, mean± S.E.M.).
Time
(weeks) Shaded Unshaded SL
1
B24.15 a
± 1.93
A28.48 a
± 2.19
NS
2
A30.10 a
± 2.44
A24.05 a
± 2.63 NS
3
B18.50 a
± 1.97
B17.80 a
± 2.43 NS
SL * *
Mean values within the same row bearing similar superscripts (small) are not
significantly different.
Mean values within the same column bearing different superscripts (capital)
are significantly different.
SL : Significance level.
* : Significant at p < 0.05.
NS: Not significant .
There was no significant effect of exposure to solar radiation on serum urea level
measured at weekly intervals during the experimental period.
4.3.1.2.6 Plasma glucose
Table 4.13 shows the results of the effects of solar radiation on plasma glucose
concentration .There was a significant decrease in plasma glucose level of the shaded
(p<0.05) and unshaded (p<0.01) group of rams in the third week . In the first and
second week, there was no significant difference in plasma glucose level between
the two groups . In the third week, the unshaded group of rams had significantly (p<
0.05) lower plasma glucose level compared to the value obtained for the shaded
group.
4.3.1.3 Semen characteristics
4.3.1.3.1 Ejaculate volume
Table 4.14 shows the results of the effect of solar radiation on the ejaculate
volume. In the shaded group of rams , the ejaculate volume was significantly (p<0.05)
higher in the second and third week of the experimental period. In the group of rams
exposed to solar radiation, the ejaculate volume decreased significantly (p<0.05) in
the third week. The ejaculate volume was significantly (p < 0.05) higher in the
ushaded group of rams compared to the respective value obtained for the shaded
group in the second week.
4.3.1.3.2 Sperm mass motility (MM)
Table 4.15 shows the results of the effects of exposure to solar radiation on
sperm MM. In the shaded group of rams, the sperm MM was significantly (p<0.05)
lower in the third week of the experimental period. For rams exposed to solar
radiation, the sperm MM tended to decrease
Table 4.13 Effect of exposure to solar radiation on plasma glucose concentration
(mg/dl) in Desert rams.
(n = 12,mean ± S.E.M.).
Time
(weeks) Shaded Unshaded SL
1
A 81.55 a
A 81.80 a NS
± 5.04 ± 6.02
2 A 85.63 a
± 2.03
A 85.10 a
± 2.66 NS
3 B 74.15 a
± 3.55
B 56.80 b
± 3.44 *
SL * **
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
*: Significant at p < 0.05.
**: Significant at p <0.01.
NS: Not significant.
Table 4.14 Effect of exposure to solar radiation on ejaculate volume (ml)
in Desert rams.
(n = 12,mean± S.E.M.).
Time
(weeks) Shaded Unshaded SL
1
B1.88 a
± 0.18
A2.80 a
± 0.63
NS
2 A2.22 b
± 0.53
A2.55 a
± 0.26 *
3 A2.38 a
± 0.65
B2.23 a
± 0.32 NS
SL * *
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level. .
*: Significant at p < 0.05.
NS: Not significant
Table 4.15 Effects of exposure to solar radiation on sperm mass motility , MM
(0 – 5) in Desert rams.
( n =12 ,mean± S.E.M.).
Time
(weeks) Shaded Unshaded SL
1
A3.75 a
± 0.14
A4.25 a
± 0.14
NS
2 A4.00 a
± 0.00
B3.25 a
± 0.48 NS
3 B3.13 a
± 0.31
B2.88 a
± 0.31 NS
SL * *
Mean values within the same row bearing similar superscripts (small) are not
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
* : Significant at p < 0.05.
NS: Not significant.
progressively during the experimental period, and the values obtained in the second
and third week were significantly (p< 0.05) lower. There was no significant
difference in MM between shaded and unshaded group of rams.
4.3.1.3.3 Sperm individual motility (IM)
Table 4.16 shows the results of the effects of exposure to solar radiation on
sperm IM. The sperm IM value obtained for the shaded rams was significantly
(p<0.05) higher in week 3 compared to values obtained for week 1 and 2. In the
unshaded rams the sperm IM was significantly (p< 0.05) lower in week 2 and 3
compared to week 1 . However, the sperm IM was significantly(p < 0.05) lower in
unshaded rams in weeks 2 and 3 compared to the respective values of the shaded
group.
4.3.1.3.4 Sperm cell concentration
Table 4.17 shows the results of the effect of exposure to solar radiation on
sperm cell concentration. The shaded group revealed insignificant increase in sperm
cell concentration during the experimental period. The unshaded group of rams
showed significantly (p< 0.05) lower values of sperm cell concentration in the
second and third week compared to the first week. The unshaded group of rams had
significantly (p<0.05) higher sperm cell concentration in the first week of the
experimental period compared to the value obtained for the shaded group .
4.3.1.3.5 Incidence of live sperm
Table 4.18 shows the results of the effect of exposure to solar radiation on the
incidence of living spermatozoa (%). In the shaded group of rams, there was no
significant change in the incidence of living sperm
Table 4.16 Effect of exposure to solar radiation on sperm individual motility, IM
(%) in Desert rams.
( n =12 , mean± S.E.M.).
Time
(weeks) Shaded Unshaded SL
1
B65.06 a
A65.01 a NS
± 11.9 ± 6.45
2 B60.15 a
± 7.07
B43.75 b
± 15.99 *
3 A76.25 a
± 3.75
AB55.10 b
± 6.45 *
SL * *
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
* : Significant at p < 0.05.
NS: Not significant .
Table 4.17 Effect of exposure to solar radiation on sperm cell concentration
(x109/ml) in Desert rams.
(n = 12, mean± S.E.M.).
Time
(weeks) Shaded Unshaded SL
1
A1.84 b
± 0.22
A3.59 a
± 0.82
*
2
A2.18 a
± 0.23
B1.48 a
± 0.25 NS
3
A2.85 a
± 0.85
B1.93 a
± 0.42 NS
SL NS *
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
*: Significant at p < 0.05.
NS: Not significant.
Table 4.18 Effect of exposure to solar radiation on the incidence of live sperm
(%) in Desert rams.
(n = 12, mean± S.E.M.)
Time
(weeks) Shaded Unshaded SL
1
A99.15 a
± 0.32
B91.23 b
± 2.97
*
2 A95.30 a
± 3.02
A98.63 a
± 0.48 NS
3 A98.18 a
± 1.41
A97.78 a
± 0.43 NS
SL NS *
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
* : Significant at p < 0.05.
NS: Not significant.
during the experimental period. In the unshaded group of rams, the incidence of
living sperms was significantly (p<0.05) higher in the second and third week
compared to the first week.The percent of live sperms was significantly (p<0.05)
lower in unshaded rams only in the first week compared to the value reported for the
shaded rams.
4.3.1.3.6 Incidence of abnormal sperm
Table 4.19 shows the results of the effect of exposure to solar radiation on the
incidence of abnormal spermatozoa (%). In the shaded and unshaded group of rams,
the percentage of abnormal spermatozoa was significantly (p<0.5) higher in the
second and third week of the experimental period compared to the first week.The
abnormal sperms percentage was significantly higher in the unshaded group of rams
in the first, second and third week (p< 0.05, p< 0.01, p< 0.001) compared to the
respective shaded group values.
4.3.1.3.7 Semen pH
Table 4.20 shows the results of the effect of exposure to solar radiation on
semen pH. . In both groups of rams, semen pH was lower in the second week of the
experimental period and the change reported for the shaded rams was significant
(p<0.05). There was no significant difference in semen pH values obtained for the
shaded and unshaded group of rams.
4.3.1.4 Scrotal circumference (SC)
Table 4.21 shows the results of the effect of exposure to solar radiation on SC.
Both groups of rams showed a gradual decrease in SC during the experimental period.
Exposure of rams to solar radiation did not
Table 4.19 Effect of exposure to solar radiation on the incidence of abnormal
sperm (%) in Desert rams.
(n =12 mean,± S.E.M.).
Time
(weeks) Shaded Unshaded SL
1
B1.38 b
± 0.38
B9.65 a
± 5.11
*
2
A4.83b
± 2.81
A22.10 a
± 11.25 **
3
A3.55 b
± 2.16
A39.63 a
± 16.78 ***
SL * *
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
*: Significant at p< 0.05.
**: Significant at p< 0.01.
***: Significant at p< 0.001.
Table 4.20 Effect of exposure to solar radiation on semen pH in Desert rams.
(n = 12 , mean± S.E.M.).
Time
(weeks) Shaded Unshaded SL
1
A7.30 b
± 0.03
A7.25 a
± 0.14
NS
2 B6.88 a
± 0.13
A6.95 a
± 0.05 NS
3 A7.38 a
± 0.13
A7.13 a
± 0.13 NS
SL * NS
Mean values within the same row bearing similar superscripts (small) are not
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
* : Significant at P < 0.05.
NS: Not significant .
Table 4.21 Effect of exposure to solar radiation on scrotal circumference (cm)
in Desert rams.
(n = 12,mean± S.E.M.).
Time
(weeks) Shaded Unshaded SL
1
A30.10 a
± 0.68
A31.88 a
± 0.72
NS
2 A29.75 a A31.13 a NS
± 1.09 ± 0.47
3 A28.88 a
± 0.83
A29.88 a
± 0.66 NS
SL NS NS
Mean values within the same row and column bearing similar superscripts are
not significantly different.
SL: Significance level.
NS: Not significant.
affect the SC measurements significantly; however, the values were slightly higher in
unshaded rams.
4.3.2 Effects of exposure to solar radiation and exhaustion test
4.3.2.1 Blood composition
4.3.2.1.1 Packed cell volume (PCV)
Table 4.22 shows the results of the effect of exhaustion test on the PCV level
of the shaded group of rams . There was no significant change in PCV level for pre-
or post-exhaustion values during the experimental period. However, the results
indicate that the post-exhaustion values of PCV level were significantly (p< 0.05)
lower during the three days of the test.
Table 4-23 shows the results of the effect of exhaustion test on the PCV level
of the unshaded group of rams. There was no significant change in the pre- exhaustion
or post-exhaustion values of PCV during the experimental period. However, the post-
exhaustion PCV level was significantly (p<0.05) lower in day 3 compared to the pre-
exhaustion value.
4.3. 2.1.2 Leukocytic indices
Table 4.24 shows the results of the effect of exhaustion test on total leukocyte
count (TLC) of the shaded group of rams. The pre-exhaustion value was
significantly(p< 0.05) higher in day 2 . The exhaustion test decreased significantly
(p< 0.05) the TLC in the first and second day compared to the third day.
Table 4-25 shows the results of the effect of exhaustion test on TLC of the
unshaded group of rams. For post-exhaustion value , a significantly (p<0.05) lower
value was obtained in the third day.
Table 4.22 Effect of exhaustion test on PCV (%) in shaded Desert rams.
(n = 24 , mean± .S.E.M.).
Time
(Days) Before exhaustion After exhaustion SL
1
A 34.33 a
± 1.86
A 27.67 b
± 1.76
*
2 A 35.50 a
± 1.89
A 31.25 b
± 2.66 *
3 A 34.33 a
± 2.03
A 29.33 b
± 3.33 *
SL NS NS
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing similar superscripts (capital) are
not significantly different.
SL: Significance level.
*: Significant at p < 0.05.
NS: Not significant.
Table 4.23 Effects of exhaustion test on PCV (%) in unshaded Desert rams.
(n = 18 , mean± S.E.M.).
Time
(Days) Before exhaustion After exhaustion SL
1
A 31.25 a
± 1.75
A 28.25 a
± 2.46
NS
2 A 32.15 a A 28.67 a NS
± 3.10 ± 2.67a
3 A 30.50 a
± 1.71
A 26.13 b
± 0.71 *
SL NS NS
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing similar superscripts (capital) are
not significantly different.
SL: Significance level.
*: Significant at p < 0.05.
NS: Not significant.
Table 4.24 Effect of exhaustion test on total leukocyte count, TLC (×103/µl)
in shaded Desert rams.
( n = 24, mean ± S.E.M.).
Time
(Days) Before exhaustion After exhaustion SL
1
B 6.28 a
± 1.51
B3.98 b
± 0.57
*
2 A 8.46 a
± 0.24
AB 4.14 b
± 0.44 *
3 B 4.50 a
± 0.26
A 5.36 a
± 0.23 NS
SL * *
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
*: Significant at p < 0.05.
NS: Not significant.
Table 4.25 Effect of exhaustion test on total leukocytes count, TLC (× 103/µl)
in unshaded Desert rams.
( n = 18 , mean± S.E. M.) .
Time
(Days) Before exhaustion After exhaustion SL
1
A 6.88 a
± 0.98
AB 5.75 b
± 1.35
*
2 A 6.98 a
± 0.82
A 7.68 a
± 1.60 NS
3 A 5.78 a
± 0.86
B 4.85 a
± 1.45 NS
SL NS *
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
*: Significant at p< 0.05.
NS: Not significant.
Compared to the pre-exhaustion value, the exhaustion test reduced significantly
(p<0.05) the TLC only in day 1.
Table 4.26 shows the results of the effect of exhaustion test on differential
leukocyte count (DLC) of the shaded group of rams. There was a progressive decrease
in the ratio of lymphocytes for pre- and post- exhaustion values, but this change was
not significant. However, compared to the pre-exhaustion values, the post-exhaustion
ratio of lymphocytes was slightly higher in the first and third day.
The exhaustion test slightly increased the pre- and post- exhaustion values of
neutrophils in the shaded group of rams. However, compared to the pre-exhaustion
values, the exhaustion test slightly decreased the ratio of neutrophils during the
experimental period.
The exhaustion test resulted in a slight increase in the value of eosinophils in
the shaded group in days 2 and 3. In the post-exhaustion state, lower values of
eosinophils were obtained compared to the pre-exhaustion values.
For post–exhaustion values of monocytes, there was a significant (p< 0.05)
increase in days 2 and 3. The exhaustion test increased the ratio of monocytes in days
2 and 3.
Table 4-27 shows the results of the effect of exhaustion test on differential
leukocytes count (DLC) of unshaded rams. The exhaustion test slightly reduced the
ratio of lymphocytes in the third day of the experimental period. The exhaustion test
slightly increased the ratio of lymphocytes compared to the respective values obtained
before exhaustion
The pre- and post-exhaustion values of neutrophils were slightly lower in the
second day. Compared to the pre-exhaustion state, exhaustion
Table 4.26 Effect of exhaustion test on differential leukocyte count, DLC
(%) in shaded Desert rams.
(n = 24, ± mean S.E.M.).
Cell type
(%) Time
(Days)
Before exhaustion
After exhaustion
SL
1
A 58.75 a
± 1.65
A 62.50 a
± 1.04
NS
2 A 58.25 a
± 2.59
A 57.25 a
± 1.97 NS
3 A 53.00 a
± 5.61
A 55.50 a
± 2.40 NS
Lymphocytes
SL NS NS
1 A 31.25 a
± 1.31
A 30.50 a
± 1.32 NS
2 A 34.00 a
± 1.96
A 31.25 a
± 1.25 NS
3 A 37.00 a
± 6.22
A 32.00 a ± 2.38
NS
Neutrophils
SL NS NS
1 A 4.22 a
± 2.02
A 2.25 a
± 0.25 NS
2 A 3.75 a
± 1.03
A 3.00 a
± 0.91 NS
3 A 4.25 a
± 1.11
A 3.00 b
± 0.71 NS
Eosinophils
SL NS NS
1 A 5.75 a
± 0.75
B 4.76 a
± 0.25 NS
Monocytes
2 A 4.11 a
± 0.41
A 8.50 a
± 2.33 NS
3 A 5.75 a
± 1.11
A 9.25 a
± 2.17 NS
SL NS *
Mean values within the same row bearing similar superscripts (small) are not
significantly different .
Mean values within the same column bearing different superscripts (capital)
are significantly different.
SL : Significance level.
* : Significant at p < 0.05.
NS.:Not significant.
Table 4.27 Effect of exhaustion test on differential leukocyte count, DLC
(%), in unshaded Desert rams
(n = 18 , mean± S.E.M).
Cell type
(%)
Time
(Days)
Before
exhaustion
After
exhaustion SL
1
A 46.67 a
± 3.84
A 50.67 a
± 6.36
NS
2 A 51.67 a
± 7.53
A 51.67 a
± 2.48 NS
3 A 52.67 a
± 8.83
A 48.00 a
± 10.97 NS
Lymphocytes
SL NS NS
1 A 46.67 a
± 4.26
A 43.33 a
± 6.17 NS
2 A 40.67 a
± 8.84
A 38.33 a
± 3.53 NS
3 A 43.33 a
± 10.87
A 47.00 a
± 11.63 NS
Neutrophils
SL NS NS
1 A 1.67 a
± 0.67
A 1.33 a
± 0.33 NS
2 A 2.33 a
± 0.33
A 3.83 a
± 0.33 NS
3 A 0.67 a
± 0.67
A 3.00 a
± 0.05 NS
Eosinophils
SL NS NS
1 A 3.67 a
± 0.88
A 4.67 a
± 1.76 NS
2 A 5.33 a
± 1.20
A 8.67 a
± 0.88 NS
3 A 3.67 a
± 1.45
A 4.00 a
± 0.01 NS
Monocytes
SL NS NS
Mean values within the same row and column bearing similar superscripts are
not significantly different.
SL : Significance level.
NS. Not significant
test slightly lowered the ratio of neutrophils , except in the third day where the post-
exhaustion ratio of neutrophils was higher.
For pre- and post-exhaustion values of eosinophils, higher values were
obtained in the second day. Post- exhaustion, the eosinophils ratio increased slightly
in the last two days compared to the respective pre-exhaustion values.
The exhaustion test slightly increased the pre- and post-exhaustion ratio of
monocytes in the second day only. Compared to pre-exhaustion state, the exhaustion
test slightly increased the ratio of monocytes.
4.3.2.1.3 Serum total protein
Table 4-28 shows the results of the effect of exhaustion test on serum total
protein concentration in shaded group of rams. The pre- exhaustion values of total
protein did not reveal a consistent pattern, but the post- exhaustion values showed
progressive decrease. For both pre- and post- exhaustion values there was a
significant reduction (p< 0.05) in the third day. The exhaustion test induced a
significant (p<0.05) decrease in serum total protein level in the second and third day
compared to the pre-exhaustion values.
Table 4-29 shows the results of the effect of exhaustion test on serum total
protein concentration of unshaded rams .For both pre- exhaustion and post-
exhaustion values, there was no significant change during the experimental period.
However, compared to the pre-exhaustion state, the post – exhaustion serum protein
levels were significantly (p< 0.05) lower in the first and second day.
4.3.2.1.4 Serum albumin
Table 4.30 shows the results of the effect of exhaustion test on serum albumin
concentration of shaded group of rams. The exhaustion test
Table 4.28 Effects of exhaustion test on serum total protein concentration (g/dl)
in shaded Desert rams.
(n = 24 ,mean± S.E.M.).
Time
(Days) Before exhaustion After exhaustion SL
1
A 7.63 a
± 0.35
A 7.68 a
± 0.33
NS
2
A 7.88 a
± 0.29
A 7.35 b
± 0.32
*
3
B 7.20 a
± 0.29
B 6.60 b
± 0.19
*
SL * *
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
* : Significant at p < 0.05.
NS: Not significant.
Table 4.29 Effects of exhaustion test on serum total protein concentration (g/dl)
in unshaded Desert rams.
(n = 18 , mean± S.E.M.) .
Time
(Days) Before exhaustion After exhaustion SL
1
A 7.73 a
A 7.13 b
*
± 0.43 ± 0.63
2 A 7.77 a
± 0.03
A 6.93 b
± 0.33
*
3 A 7.33 a
± 0.29
A 6.77 a
± 0.24
NS
SL NS NS
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing similar superscripts (capital) are
not significantly different.
SL: Significance level.
* : Significant at p <0.05.
NS:Not significant.
Table 4.30 Effect of exhaustion test on serum albumin concentration (g/dl)
in shaded Desert rams.
(n = 24 , mean± S.E.M).
Time
(Days) Before exhaustion After exhaustion SL
1 A 3.50 a
± 0.12
A 3.65 a
± 0.05
NS
2 A 3.65 a
± 0.12
A 3.65 a
± 0.16
NS
3 A 3.38 a
± 3.75
A 3.75 a
± 0.21
NS
SL NS NS
Mean values within the same row and column bearing similar superscripts are
not significantly different.
SL: Significance level.
NS: Not significant.
slightly increased the serum albumin level in day 3. The results indicate that
generally, the post – exhaustion serum albumin levels were slightly higher compared
to the respective pre-exhaustion values.
Table 4-31 shows the results of the effect of exhaustion test on serum albumin
concentration of unshaded rams. There was no significant difference in pre-
exhaustion and post-exhaustion values during the experimental period.
4.3.2.1.5 Serum urea
Table 4.32 shows the results of the effect of exhaustion test on serum urea
concentration of the shaded group of rams. There was a significant increase in urea
level for both pre-exhaustion (p<0.05) and post-exhaustion (p<0.01) values. The
exhaustion test increased the serum urea level significantly (p<0.05) in the third day
of experimental period.
Table 4-33 shows the effect of exhaustion test on serum urea concentration of
the unshaded group of rams. The exhaustion test decreased the serum urea level
slightly in days 2 and 3. There was no significant difference in pre-exhaustion and
post-exhaustion urea levels during the experimental period.
4.3.2.1.6 Plasma glucose
Table 4.34 shows the results of the effect of exhaustion test on plasma glucose
concentration in the shaded group of rams. The plasma glucose level increased
significantly (p<0.05) during the experimental period for both per-exhaustion and
post-exhaustion values. Compared to the pre-exhaustion values, the exhaustion test
increased the plasma glucose level significantly (p<0.05) in days 1 and 3.
Table 4.31 Effect of exhaustion test on serum albumin concentration (g/dl)
in unshaded Desert rams.
(n = 18 , mean± S.E.M.).
Time
(Days) Before exhaustion After exhaustion SL
1
A 3.70 a
A 3.77 a
NS
± 0.06 ± 0.22
2 A 3.67 a
± 0.17
A 3.47 a
± 0.13
NS
3 A 3.40 a
± 0.12
A 3.63 a
± 0.18
NS
SL NS NS
Mean values within the same row and column bearing similar superscripts are
not significantly different.
SL: Significance level.
NS. Not significant.
Table 4.32 Effect of exhaustion test on serum urea concentration (mg/dl)
in shaded Desert rams.
(n = 24 , mean± S.E.M).
Time
(Days) Before exhaustion After exhaustion SL
1
B 17.45 a
± 2.85
B 17.20 a
± 3.20
NS
2 B 18.38 a
± 3.17
A 21.75 a
± 2.29a
NS
3 A 21.08 b
± 3.48
A 28.40 a
± 0.16a
*
SL * **
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
* : Significant at p< 0.05.
** : Significant at p < 0.01.
NS: Not significant.
Table 4.33 Effect of exhaustion test on serum urea concentration (mg/dl)
in unshaded Desert rams.
(n = 18, mean ± S.E.M.).
Time
(Days) Before exhaustion After exhaustion SL
1
17.67 a
A 17.10 a
NS
± 0.63 ± 1.78
2 A 16.80 a
± 4.18
A 14.43 a
± 1.79
NS
3 A 18.93 a
± 2.58
A 15.57 a
± 1.85
NS
SL NS NS
Mean values within the same row and column bearing similar superscripts are
not significantly different.
SL: Significance level.
NS: Not significant.
Table 4.34 Effect of exhaustion test on plasma glucose concentration (mg/dl)
in shaded Desert rams.
(n = 24 , mean± S.E.M.) .
Time
(Days)
Before exhaustion After exhaustion SL
1
B 51.03 b
± 5.26
B 58.40 a
± 2.28
*
2 A 54.88 a
± 0.75a
B 58.50 a
± 4.30
NS
3 A 57.05 b
± 3.02
A 62.23 a
± 4.51
*
SL * *
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital)
are significantly different.
SL: Significance level.
* : Significant at p <0.05.
NS: Not significant
Table 4-35 shows the results of the effect of exhaustion test on plasma glucose
levels of unshaded rams .For post-exhaustion values , the glucose level was
significantly (p<0.05) higher in day 2. The exhaustion test increased the glucose
level significantly (p<0.05) for the three days of the experimental period.
4.3.2.2 Semen characteristics
4.3.2.2.1 Ejaculate volume
Table 4.36 shows the results of the effect of exhaustion test on ejaculate
volume in the shaded group of rams. For both the first and last sample collections,
there was progressive decrease in ejaculate volume during the experimental period
and the reduction was significant (p<0.05) in the last day of the first collection. The
ejaculate volume was significantly (p< 0.05) reduced by exhaustion in the three days
of the test.
Table 4.37 shows the results of the effect exhaustion test on ejaculate volume
in the unshaded group of rams. The value of last collection obtained in the first day
was significantly (p< 0.05) lower compared to the values obtained subsequently.
There was no significant difference between the first and last ejaculate volumes.
4.3.2.2.2 Sperm mass motility (MM)
Table 4.38 shows the results of the effect of exhaustion test on sperm MM in
the shaded group of rams. For the first collections, the exhaustion test progressively
reduced the MM, which did not attain the level of significance. However, the
reduction in MM observed for the last collections did not reveal a consistent pattern.
The exhaustion test slightly increased sperms MM in the first and third day, and it
reduced sperms MM in the second day.
Table 4.35 Effect of exhaustion test on plasma glucose concentration (mg/dl)
in unshaded Desert rams .
(n = 18 , mean± S.E.M.).
Time
(Days) Before exhaustion After exhaustion SL
1
A 50.93 b
± 9.45
B 66.43
± 5.86
*
2 A 54.00 b
± 5.12
A 71.87 a
± 6.62 *
3 A 50.00 b
± 3.41
B 67.13 a
± 7.71 *
SL NS *
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level..
* : Significant at p < 0.05.
NS: Not significant.
Table 4.36 Effects of exhaustion test on ejaculate volume (ml) of shaded Desert
rams.
(n = 54 , mean± S.E.M).
Sample collection Time
(Days) First Last SL
1
A1.50 a
± 0.20
A0.50 b
± 0.10
*
2 A1.28 a
± 0.19
A0.33 b
± 0.13 *
3 B0.87 a
± 0.09
A0.30 b
± 0.01 *
SL * NS
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital)
are significantly different.
SL: Significance level.
* : Significant at p < 0.05.
NS: Not significant
Table 4.37 Effects of exhaustion test on ejaculate volume (ml) of unshaded
Desert rams.
(n = 38 , mean± S.E.M.) .
Sample collection Time
(days) First Last SL
NS
1 A0.73 a
± 0.38
B0.60 a
± 0.23
2 A0.90 a
± 0.21
A1.05 a
± 0.75 NS
3 A0.75 a
± 0.15
A0.85 a
± 0.35 NS
SL NS *
Mean values within the same row bearing similar superscripts are not
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
* : Significant at p < 0.05.
NS:Not significant
Table 4.38 Effects of exhaustion test on sperm mass motility , MM (0-5)
of shaded Desert rams.
(n = 54 , mean± S.E.M) .
Sample collection Time
(Days) First Last SL
1
A3.25 a
± 0.25
A3.50 a
± 2.50
NS
2 A3.13 a
± 0.31
A2.00 a
± 0.58 NS
3 A2.67 a
± 0.33
A2.75 a
± 0.75 NS
SL NS NS
Mean values within the same row and column bearing similar superscripts are
not significantly different.
SL: Significance level.
NS.:Not significant .
Table 4.39 shows the results of the effect of exhaustion test on sperm MM in
unshaded group of rams. The exhaustion test did not influence significantly the sperm
MM values in the first and last semen sample collections during the experimental
period. The MM showed a slight increase in the second and third day in response to
exhaustion test.
4.3.2.2.3 Sperm individual motility (IM)
Table 4.40 shows the results of the effect of exhaustion test on the sperms IM
of the shaded group of rams. The exhaustion test significantly (p<0.05) lowered the
sperm IM in the last two days for the first collection. For the values of the last
collections, the sperm IM was significantly (p< 0.05) lower in the third day compared
to values obtained in days I and 2. However, the exhaustion test significantly (p<0.05)
reduced IM in the first and third day of sampling.
. Table 3.41 shows the results of the effect of exhaustion test on the sperms IM of
unshaded rams. For the initial collections of semen sample, the value was
significantly (p< 0.05) lower in day I; for the last collection values, the IM was
significantly (p< 0.05) lower in day 3. The exhaustion test significantly (p< 0.05)
increased IM in the first day and it decreased the value significantly(p<0.05) in the
third day of the experimental period.
4.3.2.2.4 Sperm cell concentration
Table 4.42 shows the results of the effect of exhaustion test on sperm cell
concentration of shaded rams. For the initial collections of semen samples during the
test, there was a progressive significant (p< 0.05) decrease in sperm cell
concentration.The last collection values indicate that the sperm cell concentration was
significantly (p<0.05) lower in days 2 and 3 compared to day 1 value. The exhaustion
test significantly (p<0.05) reduced sperm cell concentration in the first and second
day.
Table 4.39 Effect of exhaustion test on sperm mass motility, MM (0-5) of
unshaded Desert rams.
(n = 38 , mean± S.E.M).
Sample collection Time
(Days) First Last SL
1
A2.67 a
± 0.88
A2.50 a
± 0.12
NS
2 A2.67 a
± 0.33
A3.75 a
± 0.13 NS
3 A2.50 a
± 0.50
A2.75 a
± 0.75 NS
SL NS NS
Mean values within the same row and column bearing similar superscripts are
not significantly different
SL: Significance level.
NS: Not significant .
Table 4.40 Effect of exhaustion test on sperm individual motility, IM (%)
of shaded Desert rams.
(n = 54 , mean± S.E.M).
Sample collection Time
(Days) First Last SL
1
A57.50 a
± 10.31
A42.50 b
± 2.50
*
2 B37.50 a
± 4.33
A35.00 a
± 5.00 NS
3 B33.33 a
± 12.02a
B16.67 b
± 11.67 *
SL * *
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level .
* : Significant at P< 0.05.
NS: Not significant .
Table 4.41 Effect of exhaustion test on sperm individual motility, IM (%)
of unshaded Desert rams
(n = 38 ,mean± S.E.M.) .
Sample collection Period
(Days) First Last SL
1
B13.33 b
± 4.41
A30.30 a
± 3.10
*
2 A36.67 a
± 8.82
A35.00 a
± 15.00 NS
3 A30.00 a
± 10.00
B22.50 b
± 7.50 *
SL * *
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
* : Significant at p < 0.05.
NS:Not significant
Table 4.42 Effect of exhaustion test on sperm cell concentration (x109/ml)
of shaded Desert rams.
(n = 54 ,mean± S.E.M.).
Sample collection Time
(Days) First Last SL
1 A2.33 a
± 0.30
A1.31 b
± 0.24 *
2 B1.42 a
± 0.28
B0.61 b
±0. 70 *
3 B1.07 a
± 0.46
B0.98 a
± 0.15 NS
SL * *
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
* : Significant at p < 0.05.
NS: Not significant
Table 4.43 shows the results of the effect of exhaustion test on sperm cell
concentration of unshaded rams. The initial collection values of sperm cell
concentration were significantly (p< 0.05) lower in days 2 and 3. However, for last
sample collections, the sperm cell concentration was significantly (p< 0.05) higher in
day 3. The exhaustion test was associated with a significant (p<0.01) decrease in
sperm cell concentration in day 1; in day 3, the test caused a significant (p<0.05)
increase.
4.3.2.2.5 Incidence of live sperm
Table 4.44 shows the results of the effect of exhaustion test on live sperm
incidence of shaded rams. The exhaustion test did not influence significantly the
incidence of live sperms.
Table 4.45 shows the results of the effect of exhaustion test on live sperm
incidence of unshaded rams.For the initial semen sample collections, the live sperm
percent was significantly (p< 0.05) lower in the third day of experimental period.The
exhaustion test significantly (p<0.05) increased the live sperms incidence in the third
day of the experimental period
4.3.2.2.6 Incidence of abnormal sperm
Table 4.46 shows the results of the effect of exhaustion test on the
incidence of abnormal sperms of shaded group of rams. For the initial semen sample
collections, the abnormal sperm percent was significantly (p<0.05) lower in days 2
and 3. The last collection values indicate that the abnormal sperm percent was
significantly (p<0.05) higher in day 2 compared to values obtained in days 1 and 3.
The exhaustion test reduced the abnormal sperms percent in days 1 and 3 and it
produced a significant (p < 0.05) increase in day 2.
Table 4.43 Effects of exhaustion test on sperm cell concentration (x106 /ml)
of unshaded Desert rams.
(n = 38, mean± S.E.M).
Sample collection Time
(Days) First Last SL
1
A1.92 a
B0.41 b **
± 0.94 ± 0.01
2 B0.46 a
± 0.25
B0.39 a
± 0.18 NS
3 B0.64 b
± 0.10
A1.04 a
± 0.45 *
SL ** *
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
** : Significant at p<0.01.
* : Significant at p < 0.05.
NS: Not significant.
Table 4.44 Effects of exhaustion test on the incidence of live sperm (%)
of shaded Desert rams.
(n = 54 ,mean± S.E.M.).
Sample collection Time
(Day) First Last SL
1
A98.53 a
± 1.01
A99.65 a
± 0.35
NS
2 A98.88 a
± 0.54
A98.63 a
± 0.81 NS
3 A99.47 a
± 0.29
A97.30 a
± 0.10 NS
SL NS NS
Mean values within the same row and column bearing similar superscripts are
not significantly different.
SL: Significance level.
NS: Not significant
Table 4.45 Effect of exhaustion test on the incidence of live sperm (%)
of unshaded Desert rams.
(n = 38, mean± S.E.M).
Sample collection Time
(Days) First Last SL
1
A98.57 a
± 0.73
A99.50 b
± 1.10
NS
2 A99.23 a
± 0.43
A98.30 a
± 0.10 NS
3 B95.95 b
± 0.95
A99.25 a
± 0.25 *
SL * NS
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
*: Significant at p < 0.05.
NS: Not significant
Table 4.46 Effect of exhaustion test on the incidence of abnormal sperm (%)
of shaded Desert rams.
(n = 54,mean ± S.E.M.).
Sample collection Time
(Days) First Last SL
1
A4.65 a
± 3.23
B2.30 a
± 1.30
NS
2
B1.35 b
± 0.16
A4.97 a
± 2.95 *
3
B2.37 a
± 0.29
B2.05 a
± 1.15 NS
SL * *
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
* : Significant at p < 0.05.
NS: Not significant
Table 4.47 shows the results of the effects of exhaustion test on the incidence of
abnormal sperms of unshaded rams. For the initial semen sample collections, the
abnormal sperm percent decreased significantly (p<0.05) in days 2 and 3. For the last
collection of semen samples, the abnormal sperms percent was significantly (p<0.05)
lower in day 3.There was a significant (p< 0.05) reduction in abnormal sperm percent
in days I and 3 in response to exhaustion test, and a significant (p<0.05) increase in
abnormal sperm percent in day 2.
4.3.2.2.7 Semen pH
Table 4.48 shows the results of the effect of exhaustion test on semen pH of
the shaded rams . For the initial semen sample collections, the pH was significantly
(p<0.05) higher in days 2 and 3 compared to day 1 value. For last collections, the pH
value was slightly lower in day 3 compared to the values obtained in days 1 and 2.
The exhaustion test did not affect the pH values significantly. However, the general
pattern indicates that the last collection value was higher in days 1 and 2 and it was
lower in day 3.
Table 4.49 shows the results of the effects of exhaustion test on semen pH in
unshaded group of rams. The values obtained did not reveal a consistent pattern
related to the experimental treatments
Table 4.47 Effect of exhaustion test on the incidence of abnormal sperm (%)
of unshaded Desert rams.
(n = 38 , mean± S.E.M.).
Sample collection Time
(Days) First Last SL
1
A21.57 a
± 14.39
A12.50 b
± 0.20
*
2 B4.70 b
± 2.83
A8.40 a
± 7.50 *
3 B5.15 a
± 1.05
B2.90 b
± 0.50 *
SL * *
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
* : Significant at p < 0.05.
Table 4.48 Effect of exhaustion test on semen pH in shaded Desert rams.
(n = 38 ,mean± S.E.M.).
Sample collection Time
(Days) First Last SL
1
B7.08 a
± 0.08
A8.00 a
± 0.00
NS
2 A7.88 a
± 0.13
A8.00 a
± 0.01 NS
3 A7.83 a
± 0.12
A7.75 a
± 0.25 NS
SL * NS
Mean values within the same row bearing similar superscripts (small) are not
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
* : Significant at p < 0.05.
NS: Not significant .
Table 4.49 Effect of exhaustion test on semen pH in unshaded Desert rams.
(n = 38, mean± S.E.M.).
Sample collection Time
(Days) First Last SL
1
A7.67 a
± 0.44
A7.80 a
± 0.14
NS
2 A7.83 a
± 0.17
A7.75 a
± 0.25a NS
3 A8.00 a
± 0.1
A8.00
± 0.01a NS
SL NS NS
Mean values within the same row and column bearing similar superscripts are
not significantly different.
SL: Significance level.
NS: Not significant .
4.4. Discussion
In this experiment, the effects of chronic exposure of mature Desert
rams to direct solar radiation on thermoregulation, blood composition and
semen characteristics were investigated. The combined effects of
exposure to solar radiation and frequent ejaculation on blood composition
and semen characteristics were also evaluated.
The experiment was performed during wet summer conditions
(October and November), where the impact of thermal environment is
moderate and there is marked diurnal changes in ambient temperature
(16.25ºC) compared to mean values usually recorded during dry summer
conditions. Exposure of the treated group of Desert rams to solar
radiation induced a marked influence on the indices of thermoregulation
(Tr and RR), particularly the values obtained in the afternoon , but the
rams were able to readjust their thermoregulation. There were indications
that the measured blood metabolites and seminal traits of Desert rams
were influenced by exposure to direct solar radiation. The data obtained
also indicate that frequent ejaculation influenced certain blood
constituents and semen characteristics irrespective of thermal
environment.
4.4.1. Exposure to solar radiation
4.4.1.1. Thermoregualtion
In the present study, the mean value of rectal temperature (Tr) of
unshaded rams measured at 7:00 a.m. was significantly higher in the
second week of the experimental period compared to values obtained in
the first and third week (Table 4.3). This response is closely related to the
prevailing high ambient temperature. However, the significantly higher
Tr values measured at 2: 00 p.m in the first week of exposure to solar
radiation compared to value obtained subsequently, and the value of the
Tr obtained for the unshaded rams (Table 4.4) are clearly attributed to an
increase in the rate of heat gain from solar radiation which exceeded the
rate of heat loss. Consequently, heat storage induced an increase in body
temperature of rams. The present findings are consistent with
observations of Abdelatif and Ahmed (1992) who reported that exposure
of Desert rams to solar radiation during wet summer was associated with
an increase in Tr, particularly in the afternoon. Gupta and Acharya (1987)
reported higher Tr values in the afternoon in Chokla and Nali rams when
exposed to solar radiation for 8 hrs during extreme tropical summer
conditions. Similarly exposure of Barki rams and their cross Merino
(Azamel et al., 1987) and Corriedale wethers (Razzaque and Ibnoof,
1990) to direct solar radiation increased Tr, particularly in the afternoon.
The higher Tr values reported in Desert rams in the first week of
exposure to solar radiation and subsequent lowering indicates that Desert
rams are able to readjust metabolic rate by reduction of food intake and
enhancement of heat dissipation.
The current results indicated that the respiration rate (RR) values
obtained at 7: 00 a.m. were significantly higher in both groups of rams in
the second week of the experimental period (Table 4.5). This response
coincides with the prevailing maximum ambient temperature and Tr
values reported at 7: 00 a.m. However, the significantly higher RR values
obtained for unshaded rams compared to shaded group is attributed to the
influence of solar heat load and the need for enhancement of evaporative
heat dissipation from the respiratory tract. Turnpenny et al. (2000)
indicated that in sheep, thermal balance is achieved by panting. High
values of RR were reported in the afternoon on exposure of Desert rams
(Abdelatif and Ahmed, 1992), Barki rams and their cross, Merino
(Azamel et al., 1987) and Corriedale wethers (Razzaque and Ibnoof,
1990) to solar radiation. A similar marked increase of RR in the afternoon
was observed in unshaded Barki (Hassanian et al., 1996) and Merino
(Cloete et al., 2000) rams. The findings indicate that the Desert rams
were stressed by exposure to solar radiation. The changes in Tr and RR
indicate that the indices of thermoregulation were influenced by heat
stress.
4.4.1.2. Blood composition
The results indicate that exposure of Desert rams to solar radiation
was associated with changes in the blood parameters investigated. The
lower PCV noted in unshaded rams (Table 4.7) could be attributed to the
recognized heat induced increase in water consumption and consequently
occurrence of hypervolaemic haemodilution. The low values of PCV
previously reported on exposure of Barki rams (Hassanian et al., 1996)
and Merino ewes (Cloete et al., 2000) to solar radiation were attributed to
increased water consumption and haemodilution. However, Abdelatif and
Ahmed (1992) reported that exposure of Desert rams to solar radiation
did not influence significantly the PCV level. The low value of PCV
could also be partially attributed to low food intake and low metabolic
rate.
Habeeb et al. (1992) reported low values of PCV level in studies
on heat stressed animals and attributed this to haemodilution and
reduction in cellular oxygen requirements to minimize internal metabolic
heat production. The reduction in PCV level reported in heat stressed
rams in the present study could also be associated with endocrine
responses which retained water in intravascular compartment. In heat
stressed Lettle wethers (Guerrini and Bertchinger, 1983) and castrated
Merino rams (Parrott et al., 1988), low values of PCV were associated
with high blood level of the antidiuretic hormone vasopressin.
In the present study, both shaded and unshaded rams maintained
progressively higher total leukocyte count (TLC) during the experimental
period (Table 4.8). This increase could be associated with modulation in
the responses of the rams to thermal stress. Exposure to heat stress
stimulates the release of glucocorticoids which usually increase the
leukocytes in blood from lymphoid tissue and bone marrow (Swenson,
1993).
Bland et al. (2000) noted that adrenal steroids are essential for
homeostasis and survival during severe physiological stress. The authors
also reported that in mice, activation of ACTH receptors in the adrenal
gland, glucocorticoid act on immune tissues.
In the present study, different types of leukocytes responded
differently to the exposure of Desert rams to solar radiation (Table
4.9).The lower ratio of lymphocytes reported in the first and second
weeks of exposure to solar radiation could be related to the effects of
glucocorticoids. Ganong (2003) noted that glucocorticoids decrease the
number of lymphocytes and the size of lymph nodes and thymus by
inhibiting lymphocytes, mitotic activity and increasing destruction of
lymphocytes. The low ratio of lymphocytes observed during acute
exposure of rams to solar radiation could also be accounted for by heat –
induced lymphocytes death and removal of these cells physiologically
without inducing inflammatory responses (apoptosis) (Waheed et al.,
2002).
The significantly higher ratio of neutrophils observed in the
unshaded rams during the first week of exposure to solar radiation could
be associated with high levels of cortisol secreted during acute heat stress.
Sevi et al. (2001) reported higher number of neutrophils in Tasmania
ewes during exposure to solar radiation. The authors attributed this
response to the increased concentration of ACTH which stimulates the
production of cortisol from adrenal cortex. The remarkable eosinopenia
observed in unshaded rams in the third week of the experimental period
compared to the shaded rams values could be associated with increases in
the levels of adrenocorticoids which decrease the number of eosinophils
by increasing their sequestration in the spleen and lungs (Swenson, 1993;
Ganong, 2003). In the second and third week of exposure of rams to solar
radiation, there was a significant increase in the ratio of monocytes
compared to values obtained in the first week. This response could be
accounted for by the inhibition of migration of monocytes from spleen
and bone marrow and reduction in their circulating number in response to
short-term rise of blood cortisol. The general effect of cortisol usually
subsides during chronic heat stress and adaptation to hot environment
(Hammond et al., 1996).
In the current results, the shaded rams had significantly lower
serum total protein level in the third week of experimental period (Table
4.10). This could be related to an increase in water intake by rams
stimulated by the prevailing high ambient temperature. The lower values
of serum total protein could also be attributed to low food intake and
haemodilution.
In heat stressed Egyptian Suffolk rams, Marai et al. (2003)
reported low serum protein levels; this was attributed to increase in water
intake associated with decrease in food intake. However, the significantly
higher total protein level reported in rams exposed to solar radiation in
the third week compared to the control could be attributed to increase in
metabolism and reduction in the amount of energy retained. Beede and
Collier (1986) indicated that the general increase in metabolism in
ruminants during heat stress is mainly accounted for by tissue protein
catabolism. The increase in serum protein could also be attributed to
increased urinary nitrogen retention in response to low food intake.
Guerrini et al. (1982) reported that exposure of Lettle wethers to
experimental heat stress increased plasma protein level. The authors
attributed this response to increased nitrogen retention. However, in
Desert rams fed lucerne hay and exposed to direct solar radiation, the
plasma total protein level increased insignificantly (Abdelatif and
Ahmed, 1992).
In the current results the concentration of serum albumin was
significantly lower in the second week of exposure to solar radiation. This
response is clearly associated with high ambient temperature and
increased cortisol level, as the blood albumin concentration is inversely
related to blood cortisol level. Leonard and McMillan (1964) reported
that the decrease in the binding capacity of albumin in blood was
associated with high free blood cortisol level. However, the significantly
lower albumin level observed in the second week of the experimental
period in the unshaded rams could be related to the depressive effects of
thermostatic signals on voluntary food intake in sheep. The decline in
food intake resulted in lowering of the amount of amino acids available
for albumin synthesis in the liver (Payne and Payne, 1987). Abdelatif and
Ahmed (1992) reported that exposure of Desert rams fed lucerne hay to
solar radiation did not influence the plasma albumin concentration.
The results indicate that the serum urea concentration declined in
the third week of the experimental period in both groups of rams (Table
4.12). This could be associated with decrease in food intake. Payne and
Payne (1987) indicated that lowering the amount of protein required for
formation of NH3 which is converted to urea in the liver, is usually
responsible for decrease in blood urea concentration. However, the
general pattern indicates that during the experimental period, the serum
urea concentration was slightly lower in unshaded rams compared to
values obtained for the shaded rams, which is attributed to higher rate of
water consumption and depressive effect of thermal load on food intake.
Also the low values of serum urea could be accounted for by increased
secretion of catabolic hormones of the adrenal cortex in heat stressed
rams. Kamal and Shebaita (1972) reported that in ruminants exposed to
heat stress with low dietary protein, the secretion of the catabolic
hormones of the adrenal cortex is elevated , which results in nitrogen
losses and the nitrogen balance becomes negative. The present finding
regarding low serum urea level contradicts the results reported by
Abdelatif and Ahmed (1992) in Desert rams exposed to solar radiation.
In the current results, the slightly high plasma glucose
concentration observed in the first two weeks of the experimental period
in both groups (Table 4.13) could be related to stimulation of secretion of
glucocorticoids provoked by high ambient temperature. During heat
stress, the increase in the concentration of glucocorticoids increases
gluconeogenesis and hepatic glucogenesis (Kotby and Johnson, 1967).
The increase in plasma glucose could be attributed mainly to decrease in
metabolic activities associated with depressed peripheral glucose
utilization (Abdalla et al ., 1989). Kamal et al. (1970) noted that in
ruminants, heat stress induced inhibition of pancreatic B-cell activity and
consequent reduction of insulin secretion. Hassanain et al. (1996)
reported an increase in blood glucose level in Barki rams exposed to solar
radiation. The significantly lower plasma glucose level reported in both
groups in the third week of the experimental period and in the unshaded
rams compared to the control, could be related to low food intake in the
radiant environment and to decline of glucocorticoids secretion in
response to prolonged stress. A decrease in plasma glucose level of
Egyptian Suffolk rams in response to chronic heat stress was attributed to
low cortisol level (Marai et al., 2003).
4.4.1.3. Semen characteristics
The current results indicate that exposure of Desert rams to solar
radiation induced marked changes in seminal traits.
The ejaculate volume showed fluctuations in the shaded rams
during the experimental period, with significantly higher values obtained
in the second and third week (Table 4.14). This pattern could be
attributed to changes in the impact of the general thermal influence of the
prevailing ambient temperature (Table 4.2). However, in the group of
rams exposed to solar radiation, the ejaculate volume was progressively
reduced, particularly in the third week of the experimental period, and in
the second week compared to the value obtained for the shaded rams.
This response could be attributed to thermal stress and inhibition of the
role of the hypothalamus by reduction of prolactin hormone secretion.
Beede and Collier (1986) reported reduction of prolactin secretion, which
is necessary for the action of luteinizing hormone (LH) on leydig cells, in
response to thermal stress. The decline in ejaculate volume in rams
exposed to solar radiation could also be attributed to reduction in rete
testis fluid and its contents of androstene, progesterone and pregnenolone
(hormones considered as intermediates in biosynthesis of testosterone); a
reduction in their levels may reduce the secretory function of the
androgen dependent accessory genital gland (Main and Waites, 1973).
The present findings are in agreement with previous studies regarding
seminal traits of Egyptian Suffolk rams (Marai et al., 2003) exposed to
high ambient temperature.
In the current results, the sperm mass motility (MM) showed an
inconsistent pattern of reduction in the shaded group of rams, particularly
in the third week of the experimental period (Table 4.15). This reduction
could be related to the effects of increase in scrotal temperature in
response to the high ambient temperature during the second week of the
experimental period (Table 4-2). The unshaded rams showed a
progressive reduction in MM, in the second and third week of the
experimental period. This could be attributed to the cumulative effects of
direct exposure to solar radiation and impairment of scrotal thermo-
regulation. Jainudeen and Hafez (2000) indicated that spermatogenesis
requires a temperature considerably lower than that of the interior of the
body. The testes are maintained at a temperature 4–8º C below body
temperature in rams (Kastelic et al., 1996). The spermatozoa acquire
motility during their transit through the epididymal duct, which must be
maintained under low ambient temperature (Kastelie et al., 2000). The
authors also indicated that an increase in testicular temperature increased
metabolism with concurrent need for excess oxygen to sustain aerobic
metabolism. However, Setchell (1978) reported that in rams, blood flow
changes little in response to increase in testicular temperature and
consequently hypoxia develops. A similar decline in sperm MM was
reported in Egyptian Suffolk rams exposed to heat stress during summer
conditions (Marai et al., 2003).
In the current results, the sperm individual motility (IM) decreased
in both unshaded and shaded rams during the experimental period (Table
4.16). In the shaded rams, the increase in sperm IM was consistent and it
was remarkable in the third week. This change coincided with elevation
of ambient temperature during wet summer conditions. However, the
consistent reduction in sperm IM observed in unshaded rams, particularly
in the second and third week of exposure to solar radiation, could be
attributed to the effects of high thermal load on the scrotum. Increasing
the temperature of the epididymis disturbs its normal absorptive and
secretory functions, and changes in the ions and proteins of cauda
epididymis in heated testes usually lower the progressive motility of
sperms (Kastelic et. al, 1997., 2000). The significantly lower sperm IM
noted in the last two weeks of the experimental period in the unshaded
rams compared with the control, indicates that in addition to the general
effects of high ambient temperature on sperm IM, thermal load on Desert
rams exerted an additional detrimental effect by increasing scrotal
temperature.
The reduction in sperm cell concentration in rams exposed to solar
radiation (Table 4.17) could be associated with damage in all stages of
spermatogenesis. The findings of Kastelic et al. (1996) indicated that
spermatocytes and meiotic prophase were damaged due to thermal effects
with consequent decrease in number of spermatozoa in the ejaculate.
Scrotal hypothermia is necessary for normal spermatogenesis (Partsch et
al., 2000). However, Setchell and Waites (1971) reported that the
secretion of testicular fluid which begins before spermatogenesis is fully
established and persists if the production of spermatozoa is temporarily
stopped by locally heating the testis. Some of the constituents of the
testicular fluid are probably important in the nutrition of spermatozoa and
other germinal cells; this may influence the Meitotic division of cells
(Setchell and Waites, 1971).
The current results indicate that exposure of Desert rams to solar
radiation was associated with decrease in the percentage of live
spermatozoa (Table 4.18) in the first week of the experimental period
compared with the values obtained for the last two weeks.The
significantly lower value obtained for the first week compared to the
shaded rams could be related to the effects of solar radiation on testicular
and epididymal tissues. Exposure to heat stress alters the function of the
scrotal thermoregulation mechanism, which reduces the temperature
gradient which is usually maintained at 4–8ºC in rams (Stanbenfeldt and
Edqvist, 1993). The reduction in live sperms percent could also be
attributed to impaired heat exchange in the countercurrent system
between the spermatic artery and veins (Kastelic et al., 1996).
The results obtained in the current study indicate that the
percentage of abnormal spermatozoa was significantly higher in the
second and third week of the experimental period in the unshaded rams
(Table 4.19). The abnormal forms of head and tail and coiled tail were
probably associated with metabolic and structural changes. Brooks (1973)
indicated that the low temperature maintained in the cauda epididymis
may contribute to the longevity of spermatozoa stored in this part of the
organ. Boundy (1993) indicated that in rams, primary spermatozoa
abnormalities (abnormal heads, detached heads) occurred in testis during
spermatogenesis while secondary spermatozoal abnormalities
(protoplasmic droplets) were found in the epididymal journey and tertiary
spermatozoal abnormalities (bent and cut tails) were related to technical
errors during handling of semen sample. In ruminants, during epididymal
transit, spermatozoa acquire certain selected proteins secreted by
epithelial cells. The transfer of some of these proteins from cauda
epididymal fluid to sperm surface is temperature sensitive, being more
efficient at 32 – 37ºC at an optimal pH of 6.0–6.5; excess ambient
temperature prevents the transformation of these proteins and sperm
maturation is not completed (Freenette et al., 2002). In spermatozoa,
clusterin protein is suggested to be a survival gene, the transcription of
which is upregulated in physiologically adverse conditions (Ibrahim et al.
2001)). In increased scrotal temperature (heated for 4 days by insulation
bags), Ibrahim et al. (2001) reported increased spermatozoal apoptotic
changes associated with high percentage of clusterin in Montadale and
Texel cross rams. The significantly higher abnormal sperm percent
reported for the unshaded rams during the experimental period compared
with the values obtained for the shaded rams indicates the extent of
harmful effects of direct exposure to solar radiation on spermatogenesis
under tropical conditions.
The normal secretions of testes, epididymis and accessory genital
glands contribute in maintaining normal semen pH, in addition to sperm
cell concentration (Hafez, 1980). In the current results, the significantly
lower semen pH reported for the shaded rams in the second week of the
experimental period (Table 4.20) could be attributed to a decrease in the
secretion of the accessory genital glands.
4.4.2. Exposure to solar adiation and exhaustion test
4.4.2.1. Blood composition
The results obtained in the present study indicate that the
exhaustion test implemented by frequent electro-ejaculation of Desert
rams was associated with haematological changes.
In both shaded and unshaded rams, the PCV level declined
following the exhaustion test (Table 4.22). In the shaded rams, the PCV
values obtained post-exhaustion in the three consecutive days were
significantly lower compared to pre-exhaustion state. This could be
attributed to alterations in vasopressin secretion and water balance in
response to cortisol secretion. Parker et al. (2003) indicated that in
stressed sheep, plasma cortisol increases and enhances the secretion of
vasopressin and a consequent reduction in water loss occurs, resulting in
low PCV.
The decrease in PCV could be attributed to a transient expansion of
plasma volume to defend against water loss during frequent ejaculation
and heat stress through sweating and panting. Erickson (1993) reported
that an increase of plasma volume in equines and athletes in response to
endurance exercise may serve to defend against excessive water loss
during protracted work and heat stress by induced hypervolaemia as a
negative water balance from increased water loss. However, the
significant reduction in PCV level observed in the post-exhaustion state
during the third day only in the unshaded rams (Table 4.23) is clearly
related to heamodilution which resulted from heat stress, increased water
consumption and accentuation by excess muscle contraction associated
with frequent ejaculation.
The present results indicate that the exhaustion test was associated
with significantly lower total leukocyte count (TLC). In the shaded group
of rams, the significantly lower TLC observed post-exhaustion in the first
and second day compared with the pre-exhaustion value (Table 4.24)
could be attributed to the effects of increase in the secretion of
adrenocortical steroids. Swenson (1993) indicated that adrenocorticoids
may cause an increase in antibodies concentration in the blood through
dissolution of lymphocytes into lymphoid tissue resulting in
lymphopenia. The reduction in TLC could also be related to increase in
blood and lymph flow to the contracting muscles. Ganong (2003)
indicated that during exercise, the increase in blood flow to the active
muscles was associated with vasodilatation. In unshaded rams, the
significant reduction in TLC in the first and third day of the experimental
period (Table 4.25) could be related to the combined effects of prolonged
heat stress and frequent ejaculation.
Generally, the exhaustion test did not induce significant changes in
differential leukocyte count. However, the exhaustion test significantly
increased the ratio of monocytes in the shaded group of rams in the
second and third day of the experimental period (Table 4.26). This could
be attributed to a reduction in ACTH level and cortisol secretion as the
reduction in monocytes ratio in the first day of exhaustion may indicate
the predominance of ACTH. Erickson (1993) indicated that high cortisol
level reduces the ratio of monocytes.
The current results revealed that in the shaded rams, the exhaustion
test significantly decreased the serum total protein level in the third day
of the experimental period (Table 4.28). However, the exhaustion test
significantly reduced the total protein level post-exhaustion in the second
and third day compared with the pre-exhaustion values (Table 4.28). This
could be attributed to increased lymph flow during frequent ejaculation.
Ganong (2003) indicated that during exercise, the lymph flow is greatly
increased, limiting the accumulation of interstitial fluid in an effect
greatly increasing its turnover. In the unshaded rams, the significant
reduction in total protein level in the first and second day of exhaustion
test compared with pre-exhaustion state (Table 4.29) could be associated
with an increase in water intake and haemodilution, in addition to stress
induced by frequent ejaculation.
In the present study, the exhaustion test significantly increased
serum urea concentration in the third day of the experimental period in
the shaded rams (Table 4.32). This could be related to increase in the rate
of protein catabolism. Erickson (1993) indicated that in exercise in
endurance horses the consistent increase in plasma urea level is primarily
attributed to increase in the rate of protein catabolism.
In the current results, the exhaustion test generally increased
plasma glucose concentration in both groups of rams. In the shaded rams
(Table 4.34) the exhaustion test significantly increased glucose level in
the third day of the experimental period. The exhaustion test also
significantly increased the glucose level in the first and third day
compared to the pre-exhaustion values. As exhaustion test constitutes a
stressful condition, an increase in the level of glucocorticoids will
influence the plasma concentrations of energy substrates including
glucose. The actions of glucocorticoids include increased hepatic
glucogenesis and gluconeogene-sis. Glucose 6-phosphate activity is
increased and the plasma glucose level increases. Glucocorticoids exert
an anti-insulin action in the peripheral tissues (Erickson, 1993; Bland et
al., 2000), which increases the blood glucose level. For the unshaded
rams, the exhaustion test significantly increased plasma glucose level in
the post-exhaustion state for the three days (Table 4.35). This response
could be attributed to the combined effects of heat stress and exhaustion
test, as heat stress increases gluconeogenesis (Kamal et al., 1970).
Furthermore, a high level of epinephrine maintained during exhaustion
test stimulates the conversion of muscle glycogen to glucose phosphate.
During exercise, enzymes produced (e.g. tissue lipase) stimulate glucose
synthesis, hepatic glycogenolysis and lipolysis; these actions facilitate
metabolism to provide additional fuel (Erickson, 1993).
4.4.2.2. Semen characteristics
In the present study, frequent ejaculation and exposure to solar
radiation influenced semen characteristics. The results indicate that the
exhaustion test significantly reduced the ejaculate volume in the last
collection during the three days in shaded rams (Table 4.36). This is
clearly associated with the continuous withdrawal of semen from the
epididymal reserve and slow replacement by testicular, epididymal and
accessory genital glands secretions. Similar findings were reported in
frequently ejaculated Desert rams (Galil and Galil, 1982a) and Konya
Merino rams (Kaya et al., 2002). Frequent ejaculation of unshaded rams
significantly reduced the ejaculate volume of the last collection of the
first day (Table 4.37). This could be attributed to the effects of thermal
stress and frequent ejaculation on the testes and accessory genial glands
function.
The exhaustion test of shaded rams significantly reduced the sperm
individual motility (IM) of first collection of the last two days and last
collection of the third day (Table 4.40). This could be associated with the
time needed for spermatozoa in the epididymal transit to acquire their
ability of motility. Under normal conditions, the spermatozoa stay for
about 16 days in the epididymis of rams (Garner and Hafez, 2000).
Howarth (1969) reported that more than 3 days are required for the
passage of spermatozoa in epididymal duct for frequently ejaculated
rams. The reduction in sperm IM may also be related to insufficient
supply of Ca2+ and Mg ions from epididymal duct fluid. Kaya et al.
(2002) reported that in frequently ejaculated Konya rams, these cations
were positively correlated with sperm IM. Similarly, successive
collection of semen samples was associated with decrease in sperm IM in
Sudanese Desert rams (Galil and Galil, 1982a).
In the unshaded rams, the exhaustion test significantly lowered
sperm IM in day I for the first collection and day 3 for the last collection
(Table 4.41). This could be attributed to exhaustion of the epididymal
sperms store. Also the reduction in sperm IM could be attributed to the
low availability of energy sources in seminal plasma which include
fructose and adenosine triphosphate (ATP). The reduction in energy
sources is related to the reduction in testicular, epididymal and
accessory genital glands secretions due to thermal effects during exposure
to solar radiation. This finding indicates that exposure of Desert rams to
direct solar radiation under tropical conditions reduces sperm IM.
Consequently the fertility and ability of successful fertilization of ewes is
reduced.
The significant reduction in sperm cell concentration observed in
the first and last collections in the last two days and in the last collections
of the first and second day compared to first collection in shaded rams
(Table 4.42) in response to frequent ejaculation is clearly related to
depletion of epididymal sperm content. The tail of the epididymis
contains about 70% of the total number of spermatozoa compared to
excurrent ducts. In rams, the seminiferous tubules cycle takes 10 days
with different stages of spermatogenic wave; successive collection of
semen with lower rate of replacement of spermatozoa may result in
epididymal reserve depletion. Similar findings of reduced sperm cell
concentration in response to successive collection of semen were reported
in Desert rams (Galil and Galil, 1982a) and Merino rams (Salamon, 1962,
1964b). In Najdi rams, frequent ejaculation decreased sperm cell
concentration (Galil et al., 1984). Frequent ejaculation was also
associated with decrease in sperm cell concentration in Konya Merino
rams (Kaya et al., 2002). On the other hand, subjection of male goats to
successive collection of semen decreased sperm cell concentration (Ritar
et al., 1992; Oyeyemi et al., 2001).
In unshaded rams the exhaustion test significantly decreased the
sperm cell concentration in the first collection of the last two days and
significantly increased it in the last collection in the third day (Table
4.43). The reduction in sperm cell concentration could be associated with
interruption in spermatogenic cycle and consequently a reduction in the
number of spermatozoa produced. However, the increase in sperm cell
concentration during exposure to heat stress could be attributed to the
reduction in the ejaculate volume reported in this study. The findings
indicate that sperm cell concentration values reported were lower in
exhausted unshaded rams compared to values obtained for exhausted
shaded rams.
The present results indicate that the combined effects of exposure
to solar radiation and exhaustion test of Desert rams significantly reduced
the incidence of living sperms in the first collection of the third day and
increased it in the last collection of the third day (Table 4.45). The
reduction in living spermatozoa in the former state could be related to the
biochemical changes in spermatozoa, in addition to the influence of high
ambient temperature which alters the scrotal thermoregulation
mechanism. Kaya et al. (200) reported that frequent ejaculation of Konya
Merino rams increased sperm membrane damage and release of Aspartate
Amino Transaminase (ATA), Glutamic Pyruvic Transaminase (GPT) and
Lactate Dehydrogenase (LDH) in seminal plasma. In frequently
ejaculated Desert rams, Galil and Galil (1982a) reported low live sperm
percent.
The results indicate that the exhaustion test significantly reduced
the incidence of abnormal sperm in the first collection of the last two
days (Table 4.46). This reduction is clearly related to inadequate
epididymal maturation and continuous withdrawal of abnormal sperms
obtained. However, the increase in abnormal sperm incidence reported in
the last collection of the second day compared to the first collection value
could be associated with low calcium ions and an inadequate epididymal
maturation. Kaya et al. (2002) reported that calcium ion (Ca2+) is
negatively correlated to abnormal sperms percent in frequently ejaculated
Konya Merino rams. In frequently ejaculated Desert rams, the increase in
abnormal sperm percent was attributed to inadequate epididymal
maturation (Galil and Galil, 1982a). However, in the current results,
frequent ejaculation of unshaded rams, significantly reduced the
incidence of abnormal sperms in the first collection of the last two days
and in the last collection of the third day (Table 4.47). This response
could be attributed to reduction in the abnormal sperm percent produced
during exposure to solar radiation ,which is related to failure of the
scrotal thermoregulation mechanism. Kastelic et al. (1996) reported that
in rams, thermal stress disturbs the cooling of testicular arterial blood
exchange in spermatic cord. However, the significantly high abnormal
sperm percent reported post-exhaustion in the second day of the
experimental period could be related to the effects of frequent ejaculation.
The results showed that frequent ejaculation of shaded rams was
associated with increase in semen pH of the first collection of the last two
days. This could be attributed to the observed increase in the volume of
seminal plasma in the ejaculate. Milovanov (1962) indicated that semen
pH was influenced by the proportion of alkaline seminal plasma to the
acidic epididymal secretion. Also the reported increase in semen pH
could be attributed to changes in pH of spermatozoa related to
biochemical changes associated with frequent ejaculation (Kaya et al.,
2002). Also a low fructose content of frequently ejaculated semen could
be responsible for high semen pH. In Desert rams, Galil and Galil
(1982b) reported an increase in seminal plasma and low fructose
concentration in association with frequent ejaculation.
4.5. Summary
1. Eight entire Desert rams were used to investigate the effects of
exposure to solar radiation on thermoregulation, blood
composition and semen characteristics. The effects of exposure
to solar radiation and exhaustion test (frequent ejaculation) for
3 days on blood constituents and semen characteristics were
also examined.
2. The rectal temperature (Tr) of rams exposed to solar radiation
was significantly higher at 7: 00 a.m. and 2: 00 p.m. compared
to respective values obtained for the shaded rams.
3. The respiration rate (RR) values of unshaded rams were
significantly higher at 7: 00 a.m. and at 2: 00 p.m. compared to
values obtained for shaded rams.
4. Exposure to solar radiation significantly lowered the ratio of
eosinophils in the third week of the experimental period
compared to values reported for the shaded rams. The ratio of
monocytes increased significantly in the last two weeks of
exposure to solar radiation. Exhaustion test significantly
lowered TLC of shaded rams in the first and second day
compared to the initial values. In unshaded rams , exhaustion
test significantly reduced TLC in the first day compared to pre-
exhaustion values. The monocytes ratio was significantly
higher in the last two days of exhaustion test of shaded rams
compared to day I.
5. The PCV level of exhausted shaded rams was significantly
lower during the experimental period. Exposure to solar
radiation and exhaustion test significantly lowered the PCV
level in day 3.
6. The serum total protein level increased significantly in response
to exposure to solar radiation compared to the respective values
reported for the shaded rams. The total protein level was
significantly decreased in response to exhaustion test in days 2
and 3 compared to day 1. In unshaded rams, the exhaustion test
significantly decreased serum total protein level in the first and
second day compared to the pre-exhaustion value.
7. The serum albumin level was lower in unshaded rams
compared to values obtained for control group, and the value
obtained for the second week attained the significance level.
8. The serum urea level was significantly lower in both groups of
rams in the last week of the experimental period. Serum urea
level significantly increased in shaded rams in response to
exhaustion test, particularly in day 3.
9. The plasma glucose level was significantly lower in the last
week of the experimental period in unshaded rams compared to
respective value of the shaded rams. Post-exhaustion, the
plasma glucose level of shaded rams was significantly higher in
days 1 and 3 compared to the pre-exhaustion values .In
unshaded rams, the exhaustion test significantly increased the
glucose level in the three days compared to the pre-exhaustion
values.
10. Exposure to solar radiation significantly lowered the ejaculate
volume, particularly in the third week. The ejaculate volume
was significantly lower in unshaded rams during the second
week of the experimental period compared to the value of
shaded rams. The ejaculate volume of shaded rams was
significantly decreased in response to exhaustion test in the
three days compared to the pre- exhaustion value.
.
11. The sperm mass motility (MM) was consistently reduced
during exposure to solar radiation and the value reported in the
last week was significantly lower compared to the value of
week 1.
12. The sperm individual motility (IM) was significantly lowered
in response to exposure to solar radiation in the last two weeks.
The unshaded rams had significantly lower values of IM in the
last two weeks compared to the shaded rams. Sperm IM was
significantly reduced post-exhaustion in shaded rams in days 1
and 3. The IM values of exhausted unshaded rams obtained in
the last collection were significantly higher in the first day and
significantly lower in third day compared to the respective
values obtained in the first collections.
13. The sperm concentration was significantly lower in the last two
weeks of experimental period in the unshaded rams. In the first
week of the experimental period, the unshaded rams had
significantly higher values of sperm concentration compared to
the shaded rams. In shaded rams, the values of sperm
concentration obtained, post -exhaustion, in the last collection
in the first and second day were significantly lower compared
to the respective values of the first collection. In unshaded
rams, sperm concentration of the last collection of day 1 was
significantly lower compared to the first collection , while it
was significantly higher in day 3 compared to the initial
values.
14. The percentage of live sperms was significantly lower in the
first week of the experimental period in the unshaded rams. The
live sperm percent was also significantly lower in the first week
of exposure to solar radiation compared to the respective value
of shaded group. The percentage of live sperm of exhausted
unshaded rams was significantly higher in the third day of the
experimental period compared to the pre-exhaustion value.
15. The percentage of abnormal sperms was significantly higher in
the last two weeks of exposure to solar radiation. The values of
the unshaded rams were significantly higher compared to
respective valuess reported for the shaded rams during the
experimental period. In shaded exhausted rams, the percentage
of abnormal sperms was significantly higher in the second day
compared to respective pre-exhaustion values. In the unshaded
exhausted rams, there was a significant reduction in the
percentage of abnormal sperms of the last collections of days 1
and 3, and an increase in the last collection of day 2 compared
to the respective pre-exhaustion values.
CHAPTER FIVE
EFFECTS OF SEASONAL CHANGES IN THERMAL
ENVIRONMENT AND SHEARING ON
THERMOREGULATION, BLOOD CONSTITUENTS
AND SEMEN CHARACTERISTICS
5.1 Introduction
Exposure of sheep to climatic stress and seasonal changes affect their heat
balance and physiological responses. Heat tolerance is a complex association between
ambient temperature, humidity, radiation, avenues of evaporative heat loss and coat
characteristics (Hofman and Riegle, 1977).
In the tropics, the insulation of the hairy coat of sheep increases with coat
thickness and hair density (Bennett and Hutchinson, 1964). In the hot humid tropics,
where high ambient temperature and relative humidity may contribute more to heat
stress than solar radiation, a thick coat may not be an advantage; however, wooly
coats can be an advantage in animals that pant to lose heat (Yeates et al., 1975a). The
thermal resistance to the flow of heat from skin to the surface of the pelage depends
upon the entrapped air which occupies over 95% of the volume of hair coat. In sheep,
a protective fleece will help to combat the effects of radiation through the insulation
and cutaneous evaporation (Hofmeyr et al.1969; McArthur and Monteith, 1980). In
rams, the scrotum is ventrally located and it is protected from direct solar radiation. In
hot environments, a heavy scrotal wool growth will impede evaporation, thus
preventing the efficiency of cooling and interfering with spermatogenesis (Kastelic et
al., 1996).
Coat shedding in ruminants is considered as a seasonal phenomenon
controlled mainly by photoperiod and nutrition (Graham et al., 1959, Lincoln and
Richardson, 1998). However, in the tropics as variation in day length is less,
indigenous sheep breeds do not exhibit seasonality in coat characteristics (Mcleroy,
1962 c).
Shearing of heavily wooled animals can be used as an appropriate tool for the
prevention of hyperthermia (Fowler, 1989, 1994). However, the surface temperature
of skin rapidly increases after removal of fleece (Gerken, 1997).Shearing of sheep is
an ameliorative measure when they are kept under intensive husbandry system, and it
is advantageous when the weather is moderate and the animal is under shade (Azamel
et al., 1987; Ahmed and Abdelatif, 1992).
Newly shorn sheep are susceptible to cold and heat stress as shearing results in
changes in the physical characteristics of the fleece. This is usually associated with
doubling of the reflected sunlight, an increase in penetration of radiation to the skin,
and marked increase in total energy absorbed (Macfarlane et al.,1966). Consequently
the demand for evaporative cooling increases and the metabolism of energy and water
is disturbed. Shearing of Mediterranean Comisana breed of sheep, in mid-spring
(16ºC-28ºC) caused a fall in skin temperature, and low body heat production
(Piccione et al., 2002). Winter shearing of sheep increased food intake to meet energy
demands caused by increase in heat loss (Vipond et al., 1987). However, in harsh
desert conditions, shearing of sheep during the cold season might be physiologically
advantageous compared to summer shearing , as it facilitates heat loss and increases
food consumption (Elhadi, 1988).
Exposure of shorn sheep to cold reduces their productivity through
modification of digestion and metabolic and endocrine functions (Sano et al.,2002).A
low apparent digestibility of dry matter and organic matter was reported in shorn
Suffolk wethers exposed to cold environment (Kennedy and Milligan, 1973; Westra
and Christopherson , 1976; Kennedy et al., 1976,1982) . Previous studies on sheep
have investigated the influences of shearing on their skin temperature, respiration rate
and water turnover (Elhadi, 1988) and heat tolerance(Cloete et al,2000). Also the
effects of shearing and walking exercise on thermoregulation, food utilization and
blood metabolites in Desert rams were carried out (Ahmed and Abdelatif, 1992).
However, there is dearth of information regarding the effects of interaction between
shearing and thermal environment on blood metabolites and seminal traits of Desert
rams. The main objective of this experiment was to investigate the effects of shearing
Desert rams during winter and summer on thermoregulation, blood constituents and
semen characteristics. The effects of season, shearing and fasting on blood
constituents were also investigated in both seasons.
5.2 Experimental procedure
The experimental plan is shown in Table 5-1. Eight Desert rams were used in
the experiment. The rams were randomly assigned to two groups of 4 rams each. The
control group was kept unshorn with intact pelage, the mean length of hair was about
1.5cm, and the treated group was shorn. Shearing was performed using a manual
shearing machine , the mean length of hair left was approximately 0.5 cm in both
seasons .Both groups of rams were allowed an adaptation period of 2 weeks. This
period was followed by 4 weeks of experimental measurements. The measurements
were conducted with a similar protocol during winter and summer at the University
Farm at Shambat. The animals were allowed to graze daily from 7:00 a.m to 2:00
p.m., and they were allowed free access to tap water. The measurements of rectal
temperature (Tr) and respiration
Table 5.1 Experimental plan
Experimental period Treatment Weekly
measurements
Weekly
Sampling Analysis
Winter
(20 Jan-22 Feb. /2001)
Summer
(3 May- 5 June/2001)
-Unshorn
-Shorn
-Tr (7:00 a.m.,
2:00 p.m.).
-RR(7:00 a.m.,
2:00p.m.).
-Scrotal
circumference.
-Blood
-Semen
-Blood parameters.
-Seminal traits.
On the last day of the
fourth week before
fasting.
Sampling -Blood samples
Analysis
-Blood parameters.
Three days fasting
period.
-None
-None
On the first day
following the fasting
period.
-Blood samples
-Blood parameters.
rate (RR) were performed weekly in the morning (7:00 a.m.) and in the afternoon
(2:00 p.m.) under broken shade for 4 weeks. Blood and semen samples were also
collected weekly in the morning (8:00 a.m.) for 3 weeks. In the last day of the 4th
week, blood samples were collected. Thereafter, rams were fasted for three successive
days, there were no experimental measurements during this period. Blood samples
were collected after the third day of fasting.
Blood samples were used for determination of PCV and total and differential
leukocyte counts. Serum samples were used for the measurements of the
concentrations of total protein, albumin and urea and plasma samples were used for
the determination of glucose concentration. Semen samples were used for the
determination of ejaculate volume, and the analysis of mass and individual motility,
sperm cell concentration, live sperms percent, morphologically abnormal sperms and
semen pH. Measurements of scrotal circumference were performed weekly.
The climatic data were obtained from Shambat Meteorological Station which is
located about 1Km from the site of the experiment at the University Farm. Table 5.2
shows the ambient temperature (Ta) and relative humidity (RH) during the
experimental period.
Table 5.2 The ambient temperature (Ta) and relative humidity (RH)
during the experimental period.
Season
Winter Summer
Ta (ºC) Ta (ºC)
Time
(Weeks)
Max. Min. Mean.
RH(%)
Mean Max. Min. Mean.
RH(%)
Mean
1 28.3 12.7 20.0 23.0 42.2 23.8 33.0 14.0
2 32.4 14.1 23.5 27.0 43.3 22.9 33.1 14.0
3 30.4 14.6 22.5 25.0 41.5 27.0 34.3 17.0
4 31.8 14.5 22.2 27.0 41.3 26.3 38.8 24.0
5 31.2 16.3 24.3 20.0 41.6 23.9 32.8 19.0
Winter (20 January – 22 February, 2001).
Summer (3 May – 5 June, 2001).
5.3. Results
The effects of seasonal changes in thermal environment and
shearing on thermoregulation, blood constituents and semen
characteristics, and the combined effects of these factors and fasting on
blood composition were studied in Desert rams.
5.3.1 Effect of season on the responses to shearing
5.3.1.1 Thermoregulation
5.3.1.1.1 Rectal temperature (Tr)
Table 5.3 shows the results of the effects of season and shearing on
rectal temperature (Tr) of rams measured in the morning at 7:00 a.m. In
both seasons, shorn rams had significantly (p<0.05) lower values of Tr
compared to values obtained for unshorn rams. Both unshorn and shorn
rams had higher Tr values in summer; the seasonal change in Tr were
more pronounced in shorn rams.
Table 5.4 shows the results of the effects of season and shearing on
rectal temperature (Tr) in the afternoon at 2:00 p.m. Shearing reduced Tr
in both seasons. However, the shearing induced decline in Tr was
significant (p<0.05) in summer. For both shorn and unshorn rams, Tr
values were higher in summer compared to winter values. The seasonal
change in Tr was significant (p<0.05) in unshorn rams. Both groups of
rams showed a diurnal pattern in Tr irrespective of season. The diurnal
changes in Tr for unshorn rams were 1.0 and 0.82ºC in summer and
winter, respectively. The corresponding changes in Tr for shorn rams
were 1.08 and 2.03ºC, respectively.
Table 5.3. Effects of season and shearing on rectal temperature, Tr (ºC) of
Desert rams at 7: 00 a.m .
( n= 16, Mean ± S.E.M.).
Season Treatment
Winter Summer SL
Unshorn A38.23 a
± 0.07
A38.98 a
± 2.23 NS
Shorn B37.07 a
± 0.19
B37.84 a
± 0.12 NS
SL * *
Mean values within the same row bearing similar superscripts (small) are
not significantly different.
Mean values within the same column bearing different superscripts
(capital) are significantly different.
SL: Significance level.
* Significant at p<0.05
NS: Not significant.
Table 5.4. Effects of season and shearing on rectal temperature, Tr (ºC) of Desert rams at 2: 00 p.m..
(n =16,Mean ± S.E.M.).
Treatment Season SL
Winter Summer
Unshorn A39.05 b
± 0.06
A39.98 a
± 0.06 *
Shorn A38.90 a
± 0.05
B38.92
± 0.08a NS
SL NS *
Mean values within the same row bearing different superscripts are
significantly different.
Mean values within the same column bearing different superscripts are
significantly different.
SL: Significance level.
*: Significant at p<0.05
NS: Not significant.
5.3.1.1.2 Respiration rate (RR)
Table 5.5 shows the results of the effects of season and shearing on
the respiration rate (RR) of rams in the morning at 7:00 a.m. In both
seasons, RR was slightly lower in shorn rams compared to the control.
Both unshorn and shorn rams had significantly (p< 0.05) higher RR
values during summer compared to winter values.
Table 5.6 shows the results of the effects of season and shearing on
the respiration rate (RR) in the afternoon at 2:00 p.m. Shearing was
associated with a significant (p<0.05) decrease in RR in both seasons.
The unshorn and shorn rams had significantly (p< 0.001) higher RR
values in summer compared to respective values obtained in winter. Both
groups of rams showed a diurnal pattern in RR during summer and
winter. For the unshorn rams, the diurnal changes in RR were 48 and 16
breaths/min, for summer and winter, respectively. The corresponding
changes in shorn rams were 31 and 6 breaths/min, respectively.
5.3.1.2 Blood composition
5.3.1. 2.1 Packed cell volume (PCV)
Table 5.7 shows the results of the effects of season and shearing on
the PCV level. In both seasons, there was no significant effect of shearing
on PCV level. Both unshorn and shorn rams had lower PCV values in
summer. However, the decrease in PCV was significant (p< 0.05) in
shorn rams.
5.3.1.2.2 Leukocytic indices
Table 5.8 shows the results of the effects of season and shearing on the total leukocyte count (TLC). In both seasons, shearing did not influence the TLC significantly. The unshorn and shorn rams maintained higher TLC values in winter compared to the respective values
obtained in summer.
Table 5.5. Effects of season and shearing on respiration rate, RR (breaths/min)
of Desert rams at 7: 00 a.m.
(n = 16, Mean ± S.E.M.).
Season Treatment
Winter Summer SL
Unshorn A23.75 b
± 0.77
A31.75 a
± 3.90 *
Shorn A21.50 b
± 0.72
A30.25 a
± 4.52 *
SL NS NS
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing similar superscripts (capital) are not
significantly different.
SL: Significance level.
*: Significant at p<0.05.
NS: Not significant.
Table 5.6. Effects of season and shearing on respiration rate, RR (breaths/min)
of Desert rams at 2: 00 p.m.
(n=16, Mean ± S.E.M.).
Season Treatment
Winter Summer SL
Unshorn A39.44 b
± 4.11
A79.50 a
± 7.80 ***
Shorn B27.75 b
± 1.29
B65.75 a
± 6.94 ***
SL * *
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
*: Significant at p< 0.05
***: Significant at p<0.001.
NS: Not significant.
Table 5.7. Effects of season and shearing on PCV (%) in Desert rams.
(n = 16 ,Mean ± S.E.M.).
Season Treatment
Winter Summer SL
Unshorn A28.63 a
± 1.32
A26.00 a
± 0.79 NS
Shorn A29.06 a
± 1.11
A25.81 b
± 0.73 *
SL NS NS
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing similar superscripts (capital) are not
significantly different.
SL: Significance level.
*: Significant at p< 0.05.
NS: Not significant.
Table 5.8. Effects of season and shearing on total leukocyte count, TLC (×103/µl)
of Desert rams.
(n = 16, Mean ± S.E.M.).
Season Treatment
Winter Summer SL
Unshorn A6.33 a
± 0.54
A6.28 a
± 0.44 NS
Shorn A6.11 b
± 0.401
A5.25 b
± 0.303 NS
SL NS NS
Mean values within the same row or column bearing similar superscripts are not
significantly different.
SL: Significance level.
NS: Not significant.
Table 5.9 shows the results of the effects of season and shearing on
the differential leukocyte count (DLC). The seasonal changes in the ratio
of lymphocytes were not significant. However, in both seasons, the ratio
of lymphocytes was lower in shorn rams. There was no significant change
in the ratio of neutrophils related to season. The ratio of neutrophils was
higher in shorn rams in both seasons. The ratio of eosinophils was higher
in winter in both unshorn and shorn rams. However, the ratio of
eosinophils was higher in shorn rams in both seasons compared to the
values obtained for the control group. The seasonal changes in the ratio of
monocytes were not significant. The ratio of monocytes was lower in
shorn rams in summer, and it was lower in unshorn rams in winter.
5.3.1.2.3 Serum total protein
Table 5.10 shows the results of the effects of season and shearing
on serum total protein concentration. Shearing resulted in a slight
increase in total protein level in winter and a slight decrease in summer.
For the unshorn and shorn rams, the total protein level was slightly higher
in winter compared to respective summer values.
5.3.1.2.4 Serum albumin
Table 5.11 shows the results of the effects of season and shearing
on serum albumin concentration. Shearing was associated with a slight
decrease in the albumin level in winter and an increase in summer. The
albumin level was higher during winter compared to summer value in
both groups of rams.The increase obtained for the unshorn rams was
significantly (p <0.05) higher.
5.3.1.2.5 Serum urea
Table 5.12 shows the results of the effects of season and shearing on serum urea concentration. In both seasons, the serum urea concentration was slightly higher in shorn rams.
For both unshorn and shorn rams, the
Table 5.9. Effects of season and shearing on differential leukocyte count, DLC
in Desert rams.
(n = 16, Mean ± S.E.M.).
Season
Winter Summer Cell type
(%)
Unshorn Shorn Unshorn Shorn
SL
Lymphocytes 59.00 a
± 2.51
54.06 a
± 2.01
58.81 a
± 1.51
56.50 a
± 1.65 NS
Neutrophils 34.13 a
± 2.85
38.31 a
± 2.20
34.31 a
± 1.50
38.06 a
± 1.73 NS
Eosinophils 2.25 a
± 0.72
2.50 a
± 0.52
1.13 a
± 0.24
1.63 a
± 0.36 NS
Monocytes 4.63 a
± 0.63
5.13 a
± 0.88
5.75 a
± 0.99
3.81 a
± 0.59 NS
Mean values within the same row bearing similar superscripts are not significantly
different.
SL: Significance level.
NS: Not significant
Table 5.10. Effects of season and shearing on serum total protein concentration (g/dl)
in Desert rams .
(n = 16 , Mean ± S.E.M.).
Season Treatment
Winter Summer SL
Unshorn A7.34 a
± 0.21
A7.29 a
± 0.15 NS
Shorn A7.40 a
± 0.17
A7.13 a
± 0.19 NS
SL NS NS
Mean values within the same row or column bearing similar superscripts are not
significantly different.
SL: Significance level.
NS: Not significant.
Table 5.11. Effects of season and shearing on serum albumin concentration (g/dl)
in Desert rams .
(n= 16 ,Mean ± S.E.M.).
Season Treatment
Winter Summer SL
Unshorn A4.13 a
± 0.11
A3.50 b
± 0.05 *
Shorn A3.90 a
± 0.08
A3.55a
± 0.05 NS
SL NS NS
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing similar superscripts (capital) are not
significantly different.
SL: Significance level.
*: Significant at p< 0.05.
NS: Not significant.
Table 5.12. Effects of season and shearing on serum urea concentration (g/dl)
in Desert rams.
(n = 16 ,Mean ± S.E.M.).
Season Treatment
Winter Summer SL
Unshorn A22.48 a
± 2.42
A19.70 a
± 1.15 NS
Shorn A24.13 a
± 2.28
A20.32 a
± 1.34 NS
SL NS NS
Mean values within the same row or column bearing similar superscripts are not
significantly different.
SL: Significance level.
NS: Not significant
serum urea level was slightly higher in winter compared to the respective
values obtained in summer.
5.3.1.2.6 Plasma glucose
Table 5.13 shows the results of the effects of season and shearing
on plasma glucose concentration. The glucose level was higher in shorn
rams in both seasons. However, the increase that occurred in glucose
level was significant (p< 0.05) only in winter .The season did not
influence the plasma glucose level in unshorn rams. However, the shorn
rams had significantly (p< 0.05) higher plasma glucose level in winter
compared to the summer value.
5.3.1.3 Semen characteristics
5.3.1.3.1 Ejaculate volume
Table 5.14 shows the results of the effects of season and shearing
on the ejaculate volume. Shearing did not affect significantly the
ejaculate volume irrespective of season. The ejaculate volume was
significantly lower during summer in the unshorn (p< 0.05) and shorn
(p<0.01) rams.
5.3.1.3.2 Sperm mass motility (MM)
Table 5.15 shows the results of the effects of season and shearing
on sperm MM. Shearing slightly lowered sperms MM in both seasons .
The season influenced the sperm MM in both groups of rams; the values
obtained during summer were significantly (p<0.05) lower compared to
the respective winter values.
5.3.1.3.3 Sperm individual motility (IM)
Table 5.16 shows the results of the effects of season and shearing
on sperm IM.Shearing significantly reduced the sperm IM during winter
(p<0.01) and summer (p<0.05). In both groups of rams, summer induced
a decline in sperm IM; The unshorn rams had significantly (p<0.05)
lower IM in summer compared to winter value.
Table 5.13. Effects of season and shearing on plasma glucose concentration (g/dl)
in Desert rams .
( n = 16, Mean ± S.E.M.).
Season Treatment
Winter Summer SL
Unshorn B56.01 a
± 1.38
A55.68 a
± 1.44 NS
Shorn A64.40 a
± 2.89
A58.10 b
± 1.51 *
SL * NS
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
*: Significant at p< 0.05.
NS: Not significant.
Table 4.14 Effects of season and shearing on ejaculate volume (ml) in Desert rams.
(n =12, Mean ± S.E.M.).
Season Treatment
Winter Summer SL
Unshorn A1.32 a
± 0.13
A0.68 b
± 0.12 *
Shorn A1.39 a
± 0.09a
A0.55 b
± 0.16 **
SL NS NS
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing similar superscripts(capital) are not
significantly different.
SL: Significance level.
*: Significant at p< 0.05
**: Significant at p< 0.01.
NS: Not significant.
Table 5.15. Effects of season and shearing on sperm mass motility ,MM (0–5)
in Desert rams .
( n = 12 ,Mean ± S.E.M.).
Season Treatment
Winter Summer SL
Unshorn A3.56 a
± 0.40
A3.38 b
± 0.14 *
Shorn A3.53 a
± 0.18a
A3.25 b
± 0.36 *
SL NS NS
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing similar superscripts (capital) are
significantly different.
SL: Significance level.
*: Significant at p<0.05
NS: Not significant.
Table 5.16. Effects of season and shearing on sperm individual motility, IM
(%) in Desert rams.
(n =12 ,Mean ± S.E.M.).
Season Treatment
Winter Summer SL
Unshorn A53.33 a
± 6.40
A41.56b
± 4.02 *
Shorn B38.00 a
± 3.23
B34.18 a
± 34.17 NS
SL ** *
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
*: Significant at p<0.05
**: Significant at p<0.01
NS: Not significant
5.3.1.3.4 Sperm cell concentration
Table 5.17 shows the results of the effects of season and shearing
on sperm cell concentration .Shearing was associated with relative
increase in sperm cell concentration in winter and summer. During
summer, the sperm cell concentration was slightly lower in both groups
of rams compared to winter values.
5.3.1.3.5 Incidence of live sperm
Table 5.18 shows the results of the effects of season and shearing
on the incidence of live sperm. Shearing of rams had no significant effect
on live sperm percent in both seasons. The live sperms percent was
significantly (p< 0.05) lower during summer in the unshorn and shorn
rams compared to the respective values obtained during winter.
5.3.1.3.6 Incidence of abnormal sperm
Table 5.19 shows the results of the effects of season and shearing
on the incidence of abnormal sperm. Shearing slightly increased the
abnormal sperm percent in both seasons. The abnormal sperms percent
was significantly (p<0.01) higher during summer compared to the
respective value obtained during winter in the unshorn and shorn rams.
5.3.1.3.7 Semen pH
Table 5.20 shows the results of the effects of season and shearing
on semen pH. In both seasons, shearing was associated with a slight
increase in semen pH. In both groups of rams, the semen pH values
were slightly higher in summer compared to winter.
5.3.1.4 Scrotal circumference (SC)
Table 5.21 shows the results of the effects of season and shearing
on the SC. In both seasons, shearing had no significant effect on SC. The
season did not influence SC significantly.
Table 5.17.Effects of season and shearing on sperm cell concentration (x109/ml) in Desert rams . (n = 12, Mean ± S.E.M.).
Season Treatment
Winter Summer
SL
Unshorn
A1.59 a
±0. 20
A1.53 a
±0. 52 NS
Shorn
A2.08 a
± 0.18
A1.64 a
±0. 65 NS
SL NS NS
Mean values within the same row or column bearing similar superscripts are not
significantly different.
SL: Significance level.
NS: Not significant
Table 5.18 Effects of season and shearing on the incidence of live sperm
(%) in Desert rams.
(n = 12, Mean ± S.E.M.).
Season Treatment
Winter Summer SL
Unshorn A98.59 a
± 0.33
A96.19 b
± 0.83 *
Shorn A98.14 a
± 0.53
A95.90 b
± 0.67 *
SL NS NS
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing similar superscripts (capital) are not
significantly different.
SL: Significance level.
*: Significant at p<0.05.
NS: Not significant.
Table 5.19. Effects of season and shearing on the incidence of abnormal sperm
(%) in Desert rams.
(n = 12 ,Mean ± S.E.M.).
Season Treatment
Winter Summer SL
Unshorn A1.39 b
± 0.26
A5.08 a
± 1.21
**
Shorn A2.03 b
± 0.47
A6.58 a
± 1.81
**
SL NS NS
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing similar superscripts (capital) are not
significantly different.
SL: Significance level.
**: Significant at p< 0.01.
NS: Not significant.
Table 5.20. Effects of season and shearing on semen pH in Desert ram.
(n =12, Mean ± S.E.M.).
Season Treatment
Winter Summer SL
Unshorn A7.56 a
± 0.04
A7.61 a
± 0.11 NS
Shorn A7.67 a
± 0.06
A7.72 a
± 0.10 NS
SL NS NS
Mean values within the same row or column bearing similar superscripts are not
significantly different.
SL: Significance level.
NS: Not significant.
Table 5.21. Effects of season and shearing on scrotal circumference (cm) of Desert
rams.
(n = 12, Mean ± S.E.M.).
Season Treatment
Winter Summer SL
Unshorn A30.91 a
± 0.26
A31.91 a
± 0.37 NS
Shorn A29.53 a
± 1.67
A30.59 a
± 0.42 NS
SL NS NS
Mean values within the same row or column bearing similar superscripts are not
significantly different.
SL: Significance level.
NS: Not significant.
5.3.2 Effects of season, shearing and fasting on blood composition
5.3.2.1 Packed cell volume (PCV)
Table 5.22 shows the results of the effects of season, shearing and
fasting on PCV level. In both seasons, shearing did not affect the PCV
level significantly before and after fasting. For both groups of rams, the
post- fasting value of PCV was slightly lower in winter compared to the
pre-fasting levels. However, during summer the post- fasting value was
slightly higher in control rams and slightly lower in shorn rams compared
to the pre-fasting values.
5.3.2.2 Leukocytic indices
Table 5.23 shows the results of the effects of season, shearing and
fasting on total leukocytes count (TLC). In both groups of rams, fasting
had no significant effect on TLC during summer and winter. However,
the results indicate that for unshorn rams in both seasons, fasting slightly
decreased TLC. For shorn rams, in both seasons, fasting was associated
with increase in TLC.
Table 5.24 shows the results of the effects of season, shearing and
fasting on differential leukocyte count (DLC).During winter ,fasting
significantly (p<0.05) lowered the ratio of lymphocyte of shorn rams
compared to the unshorn.The post-fasting value of lymphocytes ratio was
significantly (p<0.05) lower in shorn rams during summer compared to
the values obtained for winter. The season and fasting did not influence
the lymphocytes ratio of unshorn rams.
Fasting was associated with an increase in the ratio of neutrophils in the shorn rams during winter and summer
compared to the unshorn, and
Table 5.22. Effects of season, shearing and fasting on PCV (%) in Desert rams .
(n = 8 ,Mean ± S.E.M.).
Season
Winter Summer Treatment
Before
fasting
After
fasting
Before
fasting
After
fasting
SL
Unshorn A29.00 a
± 2.58
A28.50 ab
± 1.06
A23.75 b
± 1.49
A24.75 ab
± 1.03 *
Shorn A29.00 a
± 2.04
A28.50 ab
± 1.66
A26.25 ab
± 0.75
A24.00 b
± 0.41 *
SL NS NS NS NS
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing similar superscripts (capital) are not
significantly different.
SL: Significance level.
*: Significant at p<0.05.
NS: Not significant.
Table 5.23. Effects of season, shearing and fasting on total leukocyte count,
TLC (X103/µl) in Desert rams .
(n = 8,Mean ± S.E.M.).
Season
Winter Summer Treatment
Before
fasting
After
fasting
Before
fasting
After
fasting
SL
Unshorn A6.13 a
± 0.38
A4.87 a
± 0.78
A6.64 a
± 1.19
A5.83 a
± 0.70 NS
Shorn A4.58 a
± 0.52
A6.81 a
± 0.81
A5.01 a
± 0.11
A6.28 a
± 1.52 NS
SL NS NS NS NS
Mean values within the same row or column bearing similar superscripts are not
significantly different.
SL: Significance level.
NS: Not significant.
Table 5.24. Effects of season, shearing and fasting on differential leukocyte count,
DLC in Desert rams.
(n := 8,Mean ± S.E.M.).
Season Winter Summer Cell type
(%) Treatment
Before fasting
After fasting
Before fasting
After fasting
SL
Unshorn A56.75 a ± 4.77
A57.00 a ± 4.51
A56.75 a ± 3.45
A54.25 a ± 3.07
NS
Shorn A51.25 b ± 3.42
B48.25 ab ± 3.64
A59.50 a ± 3.18
B46.50 b ± 5.78
*
Lymphocytes
SL NS * NS * Unshorn B33.75 b
± 3.77
A40.25 a ± 5.68
A34.25 b ± 3.90
B40.75 a ± 7.36
*
Shorn A42.50 a ± 3.50
A43.00 a ± 4.53
A32.50 b ± 3.40
A47.75 a ± 4.95
**
Neutrophils
SL * NS NS * Unshorn A3.25 a
± 0.75
A3.50 a ± 1.04
A0.75 b ± 0.48
A1.50 a ± 0.50
*
Shorn A3.25 b ± 0.83
A3.75 b ± 1.25
A1.50 b ± 0.64
A2.75 a ± 0.48
*
Eosinophils
SL NS NS NS NS Unshorn A6.00 a
± 1.29
A4.25 b ± 1.71
A5.75 a ± 1.11
A3.50 b ± 1.26
*
Shorn B3.00 b ± 0.71
A5.00 ab ± 1.58
A6.50 a ± 0.96
A3.00 b ± 0.90
*
Monocytes
SL * NS NS NS
For each parameter, mean values within the same row bearing different superscripts (small) are significantly different.
For each parameter, mean values within the same column bearing different superscripts (capital) are significantly different. SL: Significance level. *: Significant at p< 0.05 *: Significant at p< 0.01 NS: Not significant. the value obtained during summer was significant (p< 0.05) . The post-fasting values of neutrophils ratio was significantly higher during winter and summer (p< 0.05) in
unshorn rams, and during winter (p< 0.01) in shorn rams.
In both seasons, the post- fasting value of eosinophils ratio was slightly higher in shorn rams compared to the values obtained for the unshorn. In both seasons, fasting increased the ratio of eosinophils of the unshorn and shorn rams and the value obtained for summer was significant (p<
0.05). Fasting of shorn rams slightly increased the ratio of monocytes during winter and decreased it during summer compared to the respective values reported for the unshorn group of rams. The post-fasting ratio of monocytes was significantly (p<0.05) lower during summer and winter in the unshorn rams. However, in the shorn rams, the post-fasting ratio of monocytes was slightly higher during winter
and it was significantly (p<0.05) lower during summer. 5.3.2.3 Serum total protein
Table 5.25 shows the results of the effects of season, shearing and
fasting on serum total protein level. During winter, fasting significantly
(p< 0.05) increased the serum total protein level in shorn rams compared
to the respective values of unshorn rams. Compared to the respective
summer values, the post-fasting values of total protein obtained in winter
were significantly (p< 0.05) lower in the unshorn rams. However, fasting
increased the total protein level of shorn rams in both seasons and the
value obtained during winter was significantly (p< 0.05) higher compared
to summer value.
Table 5.25. Effects of season, shearing and fasting on serum total protein
concentration (g/dl) in Desert rams.
( n = 8,Mean ± S.E.M.).
Treatment Season SL
Winter Summer
Before
fasting
After
fasting
Before
fasting
After
fasting
Unshorn A8.12 a
± 0.34
B6.95 b
± 0.39
A7.48 b
± 0.40
A7.53 b
± 0.70 *
Shorn A7.93 b
± 0.05
A8.38 a
± 0.56
A7.13 b
± 0.31
A7.43b
± 0.30 *
SL NS * NS NS
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level.
*: Significant at p< 0.05.
NS: Not significant.
5.3.2.4 Serum albumin
Table 5.26 shows the results of the effects of season, shearing and
fasting on serum albumin concentration. In both seasons, fasting of shorn
rams did not significantly influence serum albumin level . Post-fasting,
the serum albumin level was significantly (p< 0.01) increased in unshorn
rams during summer compared to winter values. However, fasting of
shorn rams slightly lowered serum albumin concentration during winter,
and slightly increased it during summer.
5.3.2.5 Serum urea
Table 5.27 shows the results of the effects of season, shearing and
fasting on serum urea level. During winter, the post- fasting value of urea
was significantly (p< 0.05) higher in shorn rams. In both seasons, the
post-fasting values of serum urea level were significantly (p< 0.01) lower
in unshorn rams. However, in shorn rams, fasting was associated with a
slight increase in serum urea during winter and a significant (p<0.05)
decrease in summer.
5.3.2.6 Plasma glucose
Table 5.28 shows the results of the effects of season, shearing and
fasting on plasma glucose concentration. In both seasons, the post- fasting
glucose level was significantly (p< 0.05) higher in shorn rams compared
to unshorn. Fasting significantly lowered the plasma glucose
concentration of unshorn rams during summer (p<0.05) and shorn rams
during winter (p<0.05).
Table 5.26 Effects of season, shearing and fasting on serum albumin concentration
(g/dl) in Desert rams.
( n = 8,Mean ± S.E.M.).
Season
Winter Summer Treatment
Before
fasting
After
fasting
Before
fasting
After
fasting
SL
Unshorn A3.53 b
± 0.19
A3.48 b
± 0.11
A4.08 b
± 0.15
A4.45 a
± 0.09 **
Shorn A3.88 b
± 0.25
A3.70 b
± 0.01
A4.43 a
± 0.11
A4.45 a
± 0.06 *
SL NS NS NS NS
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing similar superscripts(capital) are not
significantly different.
SL: Significance level.
*: Significant at p < 0.05.
**: Significant at p < 0.01.
NS: Not significant.
Table 5.27 Effects of season, shearing and fasting on serum urea concentration
(mg/dl) of Desert rams.
( n =8, Mean, S.E.M.).
Season
Winter Summer Treatment
Before
fasting
After
fasting
Before
fasting
After
fasting
SL
Unshorn A23.60 a
± 0.74
B12.28 b
± 2.56
A27.78 a
± 1.54
A18.90 b
± 2.61 **
Shorn A21.75 ab
± 3.70
A23.23 ab
± 3.50
A27.35 a
± 1.32
A14.65 b
± 0.55 *
SL NS * NS NS
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level. .
*: Significant at p < 0.05.
**:Significant at p<0.01
NS: Not significant
Table 5.28. Effects of season, shearing and fasting on plasma glucose concentration
(mg/dl) in Desert rams
(n = 8 , Mean ± S.E.M.).
Season
Winter Summer Treatment
Before
fasting
After
fasting
Before
fasting
After
fasting
SL
Unshorn B49.38 b
± 8.63
B44.50 b
± 3.23
A55.64 a
± 2.53
B42.10 b
± 2.85 *
Shorn A59.63 a
± 3.53
A52.43 b
± 2.86
A56.94 ab
± 3.98
A54.22 b
± 7.03 *
SL * * NS *
Mean values within the same row bearing different superscripts (small) are
significantly different.
Mean values within the same column bearing different superscripts (capital) are
significantly different.
SL: Significance level. .
*: Significant at p< 0.05.
NS: Not significant
5.4. DISCUSSION
In this experiment, Desert rams were used to investigate the effects
of shearing during summer and winter on thermoregulation, blood
composition and semen characteristics. The combined effects of shearing
and fasting on blood metabolites were also evaluated.
4.5.1. Seasonal change and shearing
5.4.1.1. Thermoregulation
The results indicate that the thermoregulatory responses of Desert
rams were influenced by season and shearing. The rectal temperature (Tr)
was significantly lower in response to shearing at 7: 00 a.m. in both
seasons (Table 5.3) and at 2: 00 p.m. during summer compared to values
reported for the unshorn rams (Table 5.4). This response is associated
with facilitated heat dissipation via sensible means with the reduction of
hairy coat insulation. Also the response indicates changes in heat balance
of Desert rams induced by seasonal changes in thermal environment.
Mittal and Gohsh (1979) noted that the Tr of shorn Corriedale rams was
positively correlated to the prevailing ambient temperature. Moreover,
Azamel et al. (1987) indicated that shearing of Barki and Barki Merino
cross sheep decreased Tr under subtropical summer conditions due to
increase of heat loss by sensible channels. In Desert rams, Ahmmed and
Abdelatif (1992) reported lower Tr values after shearing. During winter
morning, low Tr values were reported in outbred sheep (Slee et al.,
1988), Suffolk rams (Sano et al. 1995) and Dorset sheep (Entin et al.
1998). However, lower Tr values were reported during summer shearing
in Awassi rams (Younis et al.1975) and Chokla and Nali ewes (Gupta
and Acharya, 1987). Conversely, higher Tr values were reported for
shorn Merino rams (Klemm, 1962), Awassi sheep (Eyal, 1963a) and
Merino sheep (Macfarlane et al., 1966) during summer compared to
values reported to unshorn group; this response was attributed to
penetration of sun rays to the skin surface. However, the high Tr values
reported in shorn Comisana, Barbaresca, Siciliana and Pinzirita sheep
during cold season compared to that reported for the unshorn was
associated with elevation of core temperature which was attributed to an
over-reaction to the mild cold stress resulting from shearing(Piccione et
al.,2002).
In the current results, both unshorn and shorn rams maintained
significantly higher respiration rate (RR) during summer at 7: 00 a.m.
(Table 5.5) and 2:00 p.m. (Table 5.6). This response indicates that both
groups of rams were influenced by the high ambient temperature
prevailing during the experimental period. In unshorn Down cross
wethers (Graham et al., 1959) and Merino wethers (Parer, 1963) in hot
season, the fleece exerts an extra conduction of heat. Elhadi (1988)
reported that in arid areas, the high radiant energy heats up the fleece of
unshorn and skin of shorn sheep which adds to stress produced by high
environmental temperature and enhances evaporative heat loss. High
respiration rate (RR) values were reported during the hot season in shorn
Merino sheep (Klemm, 1962; Macfarlane et al., 1966), Targhee rams
(Hofmeyr et al., 1969) and Najdi rams (Elhadi, 1988). However, in the
present study, shearing of Desert rams during both seasons lowered RR
values at 2: 00 p.m. compared to values reported for unshorn rams. This
low value could be attributed to increased evaporative heat loss from the
skin surface and respiratory tract. Azamel et al. (1987) reported low RR
values in shorn Barki and Barki -Merino cross rams during summer and
attributed this to enhancement of heat loss through the evaporative
channels. Shearing during summer was associated with a significant
decrease in RR of Awassi rams (Younis et al., 1977), Chokla and Nali
ewes (Gupta and Acharya, 1987). However, winter shearing of Suffolk
rams induced a significant decrease in RR (Sano et al., 1995).
5.4.1.2. Blood composition
The results indicate that certain blood parameters were influenced
by the experimental treatments.Shearing of Desert rams decreased
significantly the PCV level during summer (Table 5.7). This response
could be associated with an increase in water intake, water turnover and
total body water during summer. Macfarlane et al. (1966) reported an
increase in extracellular fluid of shorn Merino sheep in hot environment;
this response was associated with increased respiration rate. Elhadi
(1988) observed significant increases in water turnover and total body
water in summer shorn Najdi rams and this was associated with marked
polypnoea. However, the observations of Ahmed and Abdelatif (1992)
indicate that shearing of Desert rams under mild environmental
conditions induced a slight decrease in PCV level.
The current results revealed that in unshorn rams, the serum
albumin concentration was significantly higher during winter compared
to summer values (Table 5.11). This response could be associated with
increased food intake in the rather cool environment and elevation of the
nutritional status of the animals due to improvement of pasture. Also it
could be related to decrease in water turnover rate and relative
haemoconcentration. A significantly higher serum albumin concentration
was reported in unshorn Desert rams by Ahmed and Abdelatif (1992).
The current results indicate that the shorn rams maintained higher
plasma glucose level in winter compared to the summer value (Table
5.13). This response is most likely related to increase in food intake due
to increase in energy demand for thermogenesis. An increase in voluntary
food intake following shearing at low ambient temperature was reported
in Merino wethers (Minson, 1971) and Suffolk cross ewes (Vipond et al.,
1987). The higher glucose level reported in winter could also be
associated with inhibition of insulin secretion during cold stress.
Symonds et al. (1989) noted higher concentration of glucose level
associated with decreased insulin level in winter shorn ewes. Sano et al.
(1995) reported high glucose concentration in Suffolk rams shorn during
cold conditions, and attributed this response to increased turnover of
blood glucose through gluconeogenesis.
5.4.1.3. Semen characteristics
The general patterns indicate that the seminal traits were affected
by season and shearing of Desert rams. A significant reduction in
ejaculate volume was observed in both groups of rams during summer
compared to winter values (Table 5.14). This response indicates that both
groups of rams were influenced by increases in body and scrotal
temperatures which coincided with the prevailing ambient temperature
(Table 5.2) and eventually lowered testosterone secretion beside low food
intake. Waites and Voglmayr (1963) reported low evaporative sweating
in unshorn scrotum of Merino and Border Leicester rams with heating.
However, the authors noted an increase in sweating in shorn scrotum. In
the current study, shearing of Desert rams and their scrota during
summer could have impaired thermoregulation and induced alternations
in accessory genital gland functions and spermatogenesis. Kastelic et al.
(1996) indicated altered scrotal thermoregulation in Merino rams under
heat stress.
The current results indicate that the sperm mass motility (MM) of
both groups of rams was significantly lower during summer compared to
winter values (Table 5.15). This response is clearly associated with
increased scrotal temperature which adversely affects testicular acquired
sperm motility .Similarly summer heat stress significantly lowered sperm
mass motility of Desert rams (Galil and Galil, 1982a) and Chios cross
rams under subtropical conditions (Ibrahim, 1997).
The observations made in the present study also indicate that in
both seasons shearing of rams was associated with decline in sperm
individual motility, IM (Table 5.16). This response could be attributed to
exposure of shorn scrotum to radiant heat from the surrounding or from
the ground while the animals are lying during the experimental period in
winter and summer resulting in increased testicular and epidydimal
temperature during sperms transit and preservation. The prevailing high
ambient temperature and radiant heat may account for the extra heat load
on testes and epididymis .Kastelic et. al (1997) reported that high scrotal
and epididymal temperature interferes with sperm production and
motility.
The data indicate that in both groups of rams the live sperm percent
was significantly lower during summer compared to winter (Table 5.18).
This response is presumably associated with increased body temperature.
Moreover, the increase in radiant heat on shorn testes could increase
testicular temperature and reduce the incidence of live sperms. The
present results are consistent with the findings of Galil and Galil (1982a)
and Alsayed (1996) who reported lower percentage of live sperm in
Desert rams during summer.
The present findings revealed significantly higher abnormal sperm
percent of both groups of rams during summer compared to winter (Table
5.19). This pattern of response indicates the adverse effects of summer
season on semen characteristics. The summer thermal load increased the
incidence of abnormal sperm of unshorn Merino rams (Amir and Volcani,
1965b) and Desert rams (Galil and Galil, 1982a). Heating of the scrotum
increased the percentage of abnormal sperm (Kishore, 1983, Ibrahim et
al., 2001).
5.4.2. Seasonal change, shearing and fasting
The slight reduction in PCV level observed in the present study in
fasted shorn rams during summer compared to unshorn (Table 5.22)
could be associated with increased water intake in hot weather due to
increased evaporative heat loss beside low food intake. Also this response
could be associated with loss of ruminal fluid and slightly increased
extracellular fluid in response to fasting. Hecker et al. (1964) observed
marked reduction in ruminal fluid of fasted Merino and Romney Marsh
ewes in the first two days of the fasting period, which was associated with
expansion of extracellular fluid. Conversely, in fasted Nubian goats (Ali
and Mirghani, 1983) and Murrah buffaloes (Singh and Malik, 1979;
Nangia and Garg, 1988), fasting was associated with high PCV levels; the
authors attributed this response to decline in water consumption and
relative haemoconcen-tration.
The results indicate that fasting influenced the differential
leukocytes count of unshorn and shorn rams. Fasting of shorn rams
significantly reduced the ratio of Lymphocytes during winter compared to
the respective values of unshorn rams (Table 5.24). This response could
be related to suppression of immunity associated with fasting. Walrand et
al. (2001) and Nakamura et al. (2001) noted that in mammals, severe
undernutrition is the main cause of immunodeficiency, as it alters various
hormonal and immune conditions. Prokopenko (1998) indicated that
fasting is associated with reduction in blood level of antiproteolytic
proreins and lipid peroxidase which have an immunosuppressive activity
.However, the adrenal cortex is sensitive to fasting and responds by
diminished activity of lymphocytes (Palmblad et al., 1991). In the current
study, the significantly lower ratio of lymphocytes observed in shorn
rams during summer compared to winter values could be related to the
effects of both fasting and heat stress.
The significantly higher ratio of neutrophils observed in fasted
shorn rams during summer compared to the respective values of unshorn
rams could be associated with heat stress. Heat stress increases the blood
cortisol level and induces vasodilatation. Mitchell et al. (2000) and
Ganong (2003) indicated that cortisol activates immune system during
stress conditions. In the present study, although shorn rams were exposed
to heat stress, both groups revealed high ratio of neutrophils during
summer compared to winter.
In unshorn rams, the significantly higher ratio of neutrophils
reported post-fasting during winter could be attributed to the effects of
cold conditions. Mitchell et al. (2000) indicated that an increase in
neutrophils ratio during cold exposure is attributed to increased
mobilization from internal organs.
The significantly higher ratio of eosinophils observed post-fasting
for both groups of rams during summer could be attributed to the effects
of adrenal glands hyperactivity. Under stress conditions, cortisol secretion
increased, resulting in increased ratio of eosinophils of mice (Komori et
al., 1996).
The significant reduction in monocytes ratio in both seasons post-
fasting in unshorn rams compared to the respective values obtained for
the shorn rams (Table 5-24) could be related to the low water intake
associated with food deprivation. Barbour et al. (2004) reported
suppression of immune system in response to water deprivation in Awassi
fat – tailed sheep.
In the current results, the serum total protein level was significantly
higher during winter in fasted shorn rams compared to values obtained
for unshorn rams (Table 5.25). This response could be related to high
food intake in shorn rams before fasting coupled with nitrogen
retension. Sano et al. (1995) noted a positive protein retension in shorn
Suffolk rams at the expense of an enhancement of non- protein oxidation
during exposure to cold. However, the low total protein level of fasted
unshorn rams observed during winter compared to summer could be
attributed to loss of body protein reserve for vital processes during winter
fasting. Panaretto (1964) observed a gradual depletion of protein and fat
of body reserve in starved Boarder Leicester and Merino ewes.
The significantly higher albumin concentration observed in
unshorn rams post-fasting during summer compared to winter (Table
5.26) could be related to low water intake and haemoconcentration , in
addition to the continuous mobilization of body protein due to fasting.
Sasaki et al. (1974) reported high albumin concentration in Japanese
Corriedale wethers during fasting and attributed this to increased
mobilization of tissue protein. However, Naqvi and Rai (1988) reported
no significant influences of fasting in serum albumin concentration in
Avivastra ewes.
In the current results, the serum urea concentration was
significantly higher in shorn rams post-fasting during winter compared to
the value obtained for the unshorn (Table 5.27). This could be related to
the improvement of nutritional status before fasting. Also it could be
associated with increased blood concentration of urea and amino acids
nitrogen associated with low water intake resulting in
haemoconcentration. Eisemann and Nienaber (1990) reported that in
fasted ruminants, increased blood concentration of urea – nitrogen and
amino acids nitrogen was observed, in addition to a decrease in uptake of
ammonia by liver. However, the low level of serum urea observed post-
fasting during both seasons in unshorn rams and during winter in shorn
rams compared to summer values could be associated with increased
protein breakdown and urinary urea excretion. Burrin et al. (1989a,b)
indicated that fasting metabolism increases urinary nitrogen excretion in
ruminants indicating protein oxidation due to glucose deficiency.
However, the low urea level reported post- fasting during summer could
also be related to low fermentation capacity of rumen during exposure to
hot environment. Hutcheson and Cole (1986) reported low production of
urea in cattle in hot environment and attributed this response to low food
consumption and reduced rumen movement. Similarly, Leibholze (1970)
reported greater urinary urea excretion in fasted cross bred wethers.
In the current results, the plasma glucose level of shorn rams was
significantly higher post-fasting in both seasons compared to values
obtained for unshorn (Table 5.28). This response could be associated with
increased gluconeogenesis associated with increased adrenaline secretion.
Murray et al. (1990a) reported high glucose concentration in fasted
Spanish does due to gluconeogenesis. However, the significantly lower
plasma glucose level observed in fasted unshorn rams during summer
compared to winter values could be related to low ruminal activity in hot
environment and consequently low production of propionate. Johnson et
al. (1969) noted low production of volatile fatty acids (VFAs) in rumen
during hot environment due to low food consumption. Also this reduction
in glucose concentration could be associated with increased ruminal pH
during heat stress. In ruminants, on exposure to heat stress , ruminal
fermentation decreased and the pH increased (Hutcheson and Cole,
1986). Increased ruminal pH above 6.0, the optimum value for bacteria
producing propionic acid, reduces its concentration and consequently
lowers blood glucose level (Hara et al., 2002). However, the significantly
lower plasma glucose level post-fasting during winter in shorn rams
compared to the respective summer value could be related to increased
secretion of glucocorticoids. Sasaki et al. (1974) reported low blood
glucose level in fasted Japanese Correidale wethers which was attributed
to delayed gluconeogenesis in response to the action of glucocorticolds
with the continuous absorption of of glucose from rumen.
5.5. Summary
1. Eight Desert rams were used to investigate the effects of season
and shearing on thermoregulation blood composition and seminal
traits. The effects of fasting on blood constituents were also
examined
2. The rectal temperature (Tr) value at 7: 00 a.m. was significantly
lower in shorn rams in both seasons. Shearing during summer
significantly decreased Tr at 2:00 p.m. compared to values reported
for unshorn rams. In both seasons, shearing significantly decreased
RR at 2: 00 p.m.
3. The PCV level of shorn rams was significantly lower during
summer compared to winter values.
4. Fasting of shorn rams significantly lowered the ratio of
lymphocytes during winter compared to value reported for unshorn
rams. The ratio of lymphocytes of fasted shorn rams was
significantly lower during summer compared to winter values.
Fasting significantly increased the ratio of neutrophils during both
seasons in unshorn rams. During summer, the ratio of neutrophils
of fasted shorn rams was significantly higher compared to winter
values.The ratio of eosinophils was significantly higher during
summer in both groups of rams post – fasting compared to winter
values. The post–fasting value of monocytes ratio was significantly
lower in both seasons in unshorn rams. The post–fasting ratio of
monocytes of shorn rams was significantly lower in summer
compared to winter values.
5. Shearing significantly increased serum total protein level post-
fasting during winter compared to values obtained for unshorn
rams. The total protein level in fasted shorn rams was significantly
higher during winter compared to summer values. Serum albumin
level of fasted unshorn rams was significantly higher during
summer compared to the respective winter values. Serum urea
concentration was significantly higher during winter in fasted
shorn rams compared to values reported for unshorn. Post-fasting
serum urea concentration was significantly lower in unshorn rams
during both seasons. The post – fasting value of serum urea
concentration of shorn rams was significantly lower during
summer compared to winter value.
6. Shearing significantly increased plasma glucose level during winter
compared to values reported for unshorn. The glucose level was
significantly higher during winter compared to summer value in
shorn rams. Post-fasting, shorn rams maintained significantly
higher plasma glucose level in both seasons compared to values
obtained for the unshorn rams. The glucose level of fasted unshorn
rams was significantly lower during summer compared to the
respective winter value. In shorn rams, the plasma glucose level
was significantly lower post-fasting during winter compared to
summer value.
7. The ejaculate volume of both groups was significantly lower
during summer compared to winter values. Shearing did not
significantly influence the ejaculate volume.
8. During summer, the sperm mass motility (MM) was significantly
lower in shorn rams compared to values of unshorn rams. For both
unshorn and shorn rams, the MM was significantly lower in
summer compared to respective winter values. The sperm
individual motility (IM) was significantly lower in shorn rams in
both seasons. For unshorn rams, the sperm IM was significantly
lower in summer compared to winter values.
9. In both groups of rams, the live sperm percent was significantly
lower compared to respective winter values. In both groups of
rams, the abnormal sperm percent was significantly higher during
summer compared to winter values.
CHAPTER SIX
GENERAL DISCUSSION AND CONCLUSIONS
Under tropical conditions of arid and semi-arid range lands of
Sudan, the indigenous sheep breeds may suffer from harsh environmental
conditions which include thermal stress and shortage of food. During dry
season, low rainfall associated with poor pastures and high solar heat load
may influence the physiological responses of sheep and hamper their
productivity.
The studies described in this thesis investigated the effects of
lowering the feeding level of lucerne hay and seasonal changes in thermal
environment on thermoregulation, blood metabolites and semen
characteristics of Desert rams (Chapter 3). The effects of exposure to
solar radiation on thermoregulation, blood composition and semen
characteristics and the combined effects of exposure to solar radiation and
exhaustion test on blood composition and semen characteristics were also
examined (Chapter 4). The responses of Desert rams to shearing and
seasonal changes in thermal environment on thermoregulation, blood
composition and seminal traits, and the effects of shearing, season and
fasting on blood composition were also evaluated (Chapter 5).
Feeding lucerne hay below maintenance level lowered BW (Table
3.3) irrespective of season, which was associated with reduced scrotal
circumference (Table 3.4). This response indicates that during the dry
season and scarce forage, grazing Desert rams are likely to be subjected
to loss of BW. Furthermore, walking in pursuit of pasture raises the
energy demand. The reduced scrotal circumference associated with feed
restriction indicates that poor pasture during growth impacts on ram
lambs in delaying the age of puberty. For mature Desert rams, the
availability of good pasture is an important factor for their reproductive
efficiency as a decrease in scrotal circumference is usually associated
with reduced number of seminiferous tubules (Jainudeen and Hafez,
2000). Harvey (1995) noted that food availability is a major factor
regulating somatic axis and reproductive performance in mammals. It can
be postulated that in Desert rams, summer season is mostly considered as
the harsh period for scarcity of food and lack of water. To withstand this
nutritional stress , animals should be given dietary supplementation and
previously well fed .
The studies revealed that underfed Desert rams had low rectal
temperature, Tr (Tables 3.5, 3.6) in both seasons, a response that was
attributed to decline in metabolic rate. During summer, irrespective of the
nutritional status, all rams suffered from heat stress which was reflected
in higher Tr (Table 3.6). Also continuous exposure of the Desert rams to
solar radiation increased heat gain and raised the body temperature
(Tables 4-3, 4-4). These findings indicate that when rams are kept under
direct solar radiation during grazing, hyperthermia in addition to internal
heat production associated with feeding, and muscular activity when
searching for food and water, result in increased body temperature and
alteration in general physiological responses.
During both seasons, Tr of Desert rams was lowered by shearing
(Tables 5.3, 5.4). However, the increase in body temperature of Desert
rams observed during summer in all experiments and during exposure to
solar radiation were offset by enhancement of the cooling mechanism,
through an increase in RR (Tables 4.5, 4.6) and a decrease in exrernal
insulation by shearing (Table 5-6). Previous studies indicated that
shearing of Desert rams alleviated thermal stress as it was associated
with decrease in body temperature and respiratory frequency (Ahmed and
Abdelatif, 1992).
The studies have indicated that the blood constituents were
influenced by the experimental treatments. In shorn Desert rams, the low
PCV level (Table 5.7) could have been associated with changes in the
water relations of Desert rams in response to stimulation of the
thermoregulatory centre in the hypothalamus and to maintain appropriate
osmolatity in body fluids. Similar results representing changes in body
fluids were reported in shorn Desert rams (Elhadi, 1988). The low PCV
level reported in exhausted heat-stressed Desert rams (Table 4.23)
indicates that frequent mating of rams and increased muscular activity
and consequent increase in oxygen consumption by muscles exerted an
additional stress superimposed on the influences of heat exposure.
The immune system of animals is influenced by various stressful
conditions. The results indicated that exposure to solar radiation
influenced the leukocytic profile in rams (Table 4.9), decreases in the
ratio of eosinophils and neutrophils were attributed to their sequestration
in response to an increase in secretion of glucocorticoids. Ganong (2003)
suggested that in humans, low ratios of eosinophils could be related to
sequestration in the spleen and lung due to excessive secretion of cortisol.
Also the increase in the ratio of monocytes indicates adrenal gland
hyperactivity. The low TLC of exhausted unshaded Desert rams (Table 4-
25) was attributed to the migration of leukocytes to active muscles.
Fasting of shorn Desert rams (Table 5.24) was associated with low ratio
of lymphocytes in both seasons, which could be attributed to the effect of
increased secretions of glucocorticoides. Ganong (2003) indicated an
increase in destruction of lymphocytes due to increased glucocorticoids in
stressful conditions. During summer, Desert rams revealed high ratios of
neutrophils and eosinophils. This response could be related to increased
extravascular fluid and migration of these cells from the marginal pool to
the tissues.
The studies also revealed changes in blood metabolites of Desert
rams on exposure to various stressful conditions. Feed restriction
decreased serum total protein level of Desert rams during winter (Table
3.9) and serum albumin level in both seasons (Table 3.10). These
responses are attributed to low protein intake and reduction in ruminal
synthesis of proteins. McDonald et al (2002) indicated that ruminants
depend on food protein escaping ruminal degradation and protein
synthesized by rumen microbes.
Exposure to solar radiation increased the level of serum total
protein (Table 4.10) which was attributed to excessive protein production
from body reserve during heat stress. In ruminants, heat stress causes
mobilization of protein from the tissue to the plasma to be catabolised in
the liver (Kamal and Shebaita, 1972). However, serum albumin
concentration decreased in response to heat stress (Table 4.11). This was
clearly related to low food intake in addition to increased water
consumption for increasd evaporative heat loss which resulted in
haemodilution. The low urea concentration observed during exposure of
Desert rams to solar radiation (Table 4.12) could be associated with low
ruminal activity and production of urea, in addition to increased urinary
excretion and haemodilution due to increased water intake during heat
stress. In ruminants, an increased water intake is usually associated with
haemodilution and increases in urinary excretion of urea (Cheeke,
2005a).
The studies indicated that carbohydrate metabolism was affected
by the experimental treatments. The significantly lower plasma glucose
level in response to exposure to solar radiation (Table 4.13) was
attributed to low food intake. However, in exhausted unshaded Desert
rams, the significantly lower plasma glucose level reported (Table 4.35)
was related to low food intake in addition to increased demand of glucose
for increased muscular movement during electro-ejaculation. The
significant decrease in glucose level of shorn Desert rams during summer
(Table 5.13) could have been associated with decreased thyroid
stimulation. Dauncey (1990) and McDonlad et al. (2002) indicated that
exposure of ruminants to cold environment increased thyroid hormone
metabolism. The higher glucose level of shorn rams in winter is likely to
be related to availability of pasture and increased food intake. Previous
studies reported increased dry matter intake and body weight gain in
shorn Desert rams during mild winter conditions (Ahmed and Abdelatif,
1992). However, in the current studies, winter fasting of shorn Desert
rams increased plasma glucose level comared to the respective group
(Table 5.28).This response is attributed to increased gluconeogenesis
during food deprivation for vital body processes, while the reduction in
plasma glucose level during winter compared to summer is related to
increased demand for thermogenesis. Brockman and Laarveld (1986)
indicated that shifts in energy metabolism occur during fasting as
nutrients are metabolized from peripheral stores. Moreover, the reduction
in blood glucose during fasting is compensated by endogenous glycogen
(Naqvi and Rai, 1988).
The studies reported in this thesis indicate that the plane of
nutrition and circannual changes in tropical thermal environment
influenced the seminal traits in Desert rams. The high thermal load
encountered during summer constituted the major stressful factor which
influenced semen characteristics superimposed by feed restriction and
shearing. Prolonged exposure of the Desert rams to direct solar radiation
in the tropics during the hot season adversely affects semen
characteristics.
The restriction of food intake significantly lowered the ejaculate
volume in both seasons and the values reported during summer were
lowest (Table 3.13). This response is attributed to reduced secretion of
LH and testosterone as well as the activities of androgen–dependent
organs. This result indicates that during drought conditions or food
scarcity the reduction in ejaculate volume of Desert rams is reflected in
reduced serving capacity. Previous studies on Merino rams reported that
feed restriction was associated with low ejaculate volume (Martin and
Walkden-Brown, 1995). Prolonged exposure of Desert rams to solar
radiation resulted in low ejaculate volume (Table 4.14). This observation
indicates that exposure of Desert rams to direct solar radiation in the
tropical environment may have influences on testicular tissues and it
generally increases body temperature which alters testicular function due
to inhibition of hypothalamic hormonal functions.
The studies indicated that frequent ejaculation of unshaded Desert
rams 4–6 times/day for 3 successive days reduced the ejaculate volume
(Table 4.36). This is related to continuous withdrawal of epididymal
reserve, in addition to reduced secretions of accessory genital glands.
These findings indicate that in Desert rams, during exposure to solar
radiation under extensive husbandry conditions in the tropical
environment, frequent ejaculation will lower the serving capacity of rams.
The motility of spermatozoa was influenced by experimental
nutritional and thermal treatments. Lowering the level of feeding reduced
sperm mass motility (MM) of Desert rams (Table 3.14). This response is
attributed to a decrease in nutritive materials of seminal plasma necessary
for sperm motility, which are derived from blood metabolites. However,
this response was aggravated by hot summer conditions as a result of
increase in the metabolic rate of spermatozoa. The MM of spermatozoa
was also reduced on exposure of rams to solar radiation (Table 4.15).
This was clearly associated with impairment of testicular
thermoregulation. Previous studies indicated that unshaded Suffolk rams
had low MM (Marai et al., 2003). The sperm individual motility was also
affected by the treatments, it showed a significant decline in response to
feed restriction irrespective of season (Table 3.15), which denotes the role
of epididymal secretions as sperms acquire motility in their epididymal
transit. This observation indicates that during the dry season, poor
pastures will influence the sperm motility and fertilizing capacity of
ejaculate as individual motility of sperms is a major factor for ova
fertilization. Frequent ejaculation of unshaded rams revealed lower sperm
individual motility (Table 4.41). Kaya et al. (2002) reported low sperm
individual motility in Konya Merino rams when frequently ejaculated.
Shearing of Desert rams during summer and winter was associated with a
reduction in sperm individual motility (Table 5-16). This result indicates
that the hazard of exposure of shorn scrotum to summer and winter sun
lowers its thermoregulatory efficiency.
The significant lowering of sperm cell concentration in response to
feed restriction of Desert rams in both seasons (Table 3-16) was
associated with reduced scrotal circumference observed in the studies,
which indicates reduced number of seminiferous tubules and
consequently sperm production. The sperm cell concentration was also
reduced when Desert rams were exposed to solar radiation (Table 4.17),
which could be related to testicular degeneration in response to thermal
stress. Jainudeen and Hafez (2000) indicated that increasing scrotal
temperature lead to testicular degeneration. Frequent ejaculation of
unshaded Desert rams lowered sperm cell concentration (Table 4.43); this
was attributed to low number of sperm produced and continuous
evacuation of epididymal tail. Galil et al. (1984) reported low sperm
concentration in Najdi rams after frequent ejaculation.
The reduction in live sperm percent in response to feed restriction
during summer (Table 3.17) was attributed to less nutritive materials
necessary for intact membrane coupled with summer heat load. However,
the decline in the percentage of live sperms reported during exposure of
Desert rams to solar radiation (Table 4.18) is clearly associated with
increased number of dead sperms due to increased testicular temperature.
Frequent ejaculation of unshaded Desert rams increased the percentage of
live sperms in the last two days compared to the initial value (Table
4.45), indicating removal of dead sperms that resulted from exposure to
solar radiation.
The percentage of abnormal sperm was significantly higher in
response to feed restriction during summer (Table 3.18). Also exposure
of Desert rams to solar radiation increased the incidence of abnormal
sperms (Table 4.19) due to damage in stages of spermatogenic cycle and
inadequate epididymal maturation. Ibrahim et al., (2001) reported an
increase in abnormal sperms incidence in Montedale cross Texel rams
when their scrota were heated. However, frequent ejaculation reduced the
abnormal sperm percent (Table 4.47) of unshaded Desert rams, which
was induced by exposure to heat stress.
The effects of feed restriction, seasonal changes in thermal
environment, exposure to solar radiation and exhaustion test and shearing
on semen characteristics were investigated in the studies. Further studies
are needed to evaluate the effects of these factors on biochemical,
histochemical and histological characteristics of testicular tissues and
seminal plasma in the tropics. Future studies should also assess the effects
of nutritional and environmental factors on the hypothalamo–pituitary–
testicular axis and endocrine responses. Evaluation of the fertilizing
capacity of ejaculates collected from Desert rams exposed to nutritional
and environmental stress will verify their reproductive efficiency.
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بسم اهللا الرحمن الرحيم
األطروحةة صالخ
على تنظيم ية والبيئيةائالغذالعوامل بعض استقصاء تأثيرات الدراسة الى تهدف هذه
وخصائص blood composition، مكونات الدم thermoregulation درجة حرارة الجسم
تقييم على ارب اشتملت التج. في الكباش الصحراوية semen characteristicsالسائل المنوي
من المعدل العادي في فصلي % 33و % 66خفض مستوى التغذية بالبرسيم الجاف تأثير
. مؤيضات الدم وخصائص السائل المنى، واثر ذلك على التنظيم الحراري للجسمالصيف والشتاء
على للكباش exhaution test التعرض ألشعة الشمس واإلجهاد الجنسي آما تمت دراسة اثر
خفض أيضا تمت دراسة اثر . مكونات الدم وخصائص السائل المنوي، م الحراري للجسمالتنظي
على االستجابات في فصلي الصيف والشتاء shearing and fasting والصومغطاء الصوف
. الفسيولوجية
للكباش في فصلي الصيف % 33أدي تخفيض مستوى التغذية من المعدل العادي بنسبة
إنخفضت درجات حرارة الجسم في . ض في وزن الجسم ومحيط الخصيتينوالشتاء إلى إنخفا
آما إنخفض معدل التنفس ،الصباح والظهيرة وآان هنالك فرق واضح بين الدرجتين أثناء النهار
أما ترآيز البروتين الكلي في السيرم فقد إنخفض في فصل الشتاء فقط إستجابة .في فترة الصباح
خفض . إنخفض ترآيز األلبيومين في فصلي الشتاء والصيف معًالخفض مستوى التغذية بينما
مستوى التغذية في الكباش أدى إلى إنخفاض في حجم السائل المنوي، الحرآة الفردية للنطاق
في ها من ونسبة الحي فوترآيزها في فصلي الصيف والشتاء بينما إنخفضت الحرآة الكلية للنطا
وآانت خصائص .طبيعية الشكل في فصل الصيف فقط الغير فوزادت نسبة النطافصل الصيف
.السائل المنوي أقل مستوى في فصل الصيف عنها في فصل الشتاء
في أدى تعرض الكباش ألشعة الشمس إلى إرتفاع درجة حرارة الجسم في الصباح
التنفس معدل ارتفعبينما األول اإلسبوع فىظهيرةال و فى فترة الثاني من فترة التجربةاألسبوع
بالنسبة إلى مكونات الدم فقط إنخفضت .في الصباح والظهيرة في اإلسبوع األخير من التجربة
في اإلسبوعين األخيرين من تعرض الكباش ألشعة الشمس neutrophilsنسبة الكريات المتعادلة
إنخفضت نسبة الكريات الحمضيةو monocytesزادت نسبة الكريات األحادية بينما
eosinophils آيز البروتين رتآان فقد مقارنة بقيم الكباش التي في الظل في اإلسبوع األخير
بينما انخفض ترآيز األلبيومين في . من فترة التجربةلث اإلسبوع الثافيأعلي الكلي في السيرم
1
السيرم في االسبوع الثاني وانخفض ترآيز اليوريا ي السيرم وجلكوز البالزما في االسبوع
. الثالث من التجربة
إنعكس أثر التعرض ألشعة الشمس على خصائص السائل المنوي في خفض آل من
يز النطاف ونسبة الحي منها، بينما حجم السائل المنوي، الحرآة الكلية والفردية للنطاف، ترآ
اإلجهاد الجنسي للكباش لمدة ثالثة أيام متتالية .زادت نسبة النطاف ذات األشكال غير الطبيعية
في اليوم األخير والعدد الكلي PCVخالل تعرضها ألشعة الشمس أدي إلى خفض مكداس الدم
األول والثاني في اليومآيز البروتينلكريات الدم البيضاء في اليوم األول آما أدي إلى خفض تر
نسبة الحرآة الفردية للنطاف، انخفضت. في اليوم الثاني وزاد ترآيز جلكوز البالزماللتجربة
لإلجهاد الجنسي والتعرض ألشعة استجابةها مناألشكال الغير طبيعية ونسبة ترآيز النطاف
اد الجنسي للكباش التي في الظل إلى أدي اإلجه. بينما زادت نسبة الحي من النطاف معاالشمس
وعدد في اليوم األول والثاني TLC الدم والعدد الكلي لكريات إلى ثالثة أيام خفض مكداس الدم
في آما أدي أيضًا إلى خفض ترآيز البروتين الكلي في السيرم في اليوم األول الكريات األحادية
في وجلوآوز البالزمافي اليوم األخير ولينا وزيادة ترآيز الباليوم األول والثاني من التجربة
أدي إلى خفض حجم للكباش التي في الظل اإلجهاد الجنسي. اليوم األول واألخير من التجربة
في ، ترآيزها في اليوم األول والثالث، الحرآة الفردية للنطاف في األيام الثالث السائل المنوي
. في اليوم الثانيغير طبيعيةوزيادة نسبة النطاف الاليوم األول والثاني
خفض غطاء الصوف في الكباش الصحراوية أدي إلى خفض درجة حرارة الجسم
بينما إنخفض معدل . صباحًا في فصل الشتاء والصيف وفي الظهيرة في فصل الصيف فقط
فى بالنسبة لمكونات الدم فقد أدى إزالة الصوف من الكباش.التنفس في الظهيرة في الفصلين
أدى خفض غطاء . مقارنة بقيم الصيف نسبة ترآيز جلكوز البالزماارتفاع في الى فصل الشتاء
الصوف في الكباش إلى إنخفاض في الحرآة الكلية للنطاف صيفًا والفردية في فصلي الشتاء
مقارنة مع القيم المتحصل عليها في الكباش آاملة غطاء الصوف فقد إنخفض عدد . والصيف
فصلي إستجابة لخفض غطاء الصوف ومنع الغذاء في lymphocytes لليمفاويةالكريات ا
أدى الصوم إلى زيادة نسبة . الصيففي بينما زادت نسبة الكريات المتعادلةوالصيف الشتاء
آريات الدم المتعادلة في الحيوانات ذات الصوف ومنخفضة الصوف في فصل الصيف
البروتين الكلي في آل من إرتفع ترآيز. monocytesآريات الدم األحادية نسبة وانخفضت
رآيزت السيرم والبولينا في الشتاء إستجابة لمنع الغذاء وخفض غطاء الصوف بينما إنخفض
وارتفع ترآيز جلكوز البالزما في الصيف والشتاء مقارنة مع قيم حيوانات .البولينا في الصيف
2
في حيوانات الظل . لشتاء مقارنة مع قيم الصيفبينما انخفض ترآيز جلوآوز البالزما في االظل
أدى الصوم إلى زيادة نسبة آريات الدم المتعادلة والحمضية في فصل الصيف وخفضت نسبة
الكريات األحادية في فصلي الصيف والشتاء، آما أدى الصوم إلى زيادة مستوى ألبيومين السيرم
يف والشتاء وجلوآوز البالزما في بولينا السيرم في فصلي الصخفض ترآيز في فصل الصيف
. فصل الصيف
نتائج هذه الدراسة أوضحت أن خفض مستوى الغذاء أدى إلى حدوث تغييرات إيجابية
أيضا أوضحت الدراسة إن للكباش الصحراوية . في االستجابات الفسيولوجية للضأن الصحراوي
يؤثر سلبا على التنظيم اد الحراري اإلجه. المقدرة على التأقلم في حالة تعرضها ألشعة الشمس
اإلجهاد الجنسي مع تعرض الكباش .السائل المنويخصائص الحراري لكيس الصفن وبالتالي
إزالة غطاء الصوف صيفا . الصحراوية ألشعة الشمس لم يكن له إي اثر إجهادي إضافي عليها
ها األثر السلبي على ن لأثر اإليجابي على عملية التنظيم الحراري للجسم بينما آاله وشتاء
.حرآة النطاف
3