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Estrus and ovulation
synchronization in beef
heifers
Dr. Marcos G Colazo Research Scientist, Alberta Agriculture & Rural
Development
Edmonton, Alberta, Canada E-mail: marcos.colazo@gov.ab.ca; mgcolazo@yahoo.com
Outline of talk
Estrous cycle of the heifer
What is CR and PR?
Controlling the estrous cycle – Synchronization of estrus – Synchronization of ovulation – Protocols
Advantages and disadvantages
Cost
Estrous cycle of the heifers
Average 21 days long (18 to 24)
Two phases luteal and follicular
Four stages – Proestrus (Day 18-20)
– Estrus (Day 0)
– Metestrus (Day 1 - 3)
– Diestrus (Day 4 - 17)
Pregnancy Rate (PR) =
Estrus Detection Efficiency (EDE) x
Conception rate (CR)
n EDE CR PR
(%) (%) (%)
100 50 50 25
100 80 50 40
100 100 50 50
Shortening the luteal phase
(e.g.)
ProstaglandinF2
Simulating the luteal phase
(e.g.)
Progesterone
Controlling the estrous cycle
Controlled follicle growth & ovulation
(e.g.)
Estrogens & GnRH
Commercially available PGF products
0 7 14 21
Active CL, D 5-16
PGF effective
5
10
15
20
Day of cycle
Follicle s
ize (mm)
Growing CL Regressing CL
Ov Ov
Estrus Pro estrus Diestrus Metestrus
Common Protocols using PGF
Estrus detection and AI
Estrus detection and AI
Estrus detection and AI
6 days
14 days PGF PGF
PGF PGF
PGF
Estrus detection and AI
11 days
EDR~80%
EDR~85%
EDR~85%
Distribution of heat in beef heifers given PGF 11 d apart
0
10
20
30
40
50
60
% in
heat
24 36 48 60 72 84 96
Hours after second PGF
Total in heat: 84%
Butler et al., 2001
0
10
20
30
40
50
60
% in
heat
36 48 60 72 84 96 108 120 132 144
Hours after second PGF
Total in heat: 86%
Colazo, unpublished
Distribution of heat in Holstein heifers given PGF 14 d apart
n = 132
Conception Rate
0
10
20
30
40
50
60
70
80
90
100
%
P
r
e
g
n
a
n
t
14 d apart PGF
5d Modified Cosynch
a, b Effect of TRT P < 0.05
a
b
80.9% 60.0%
~half AI with sexed semen
Shortening the luteal phase
(e.g.)
ProstaglandinF2
Simulating the luteal phase
(e.g.)
Progesterone
Controlling the estrous cycle
Controlled follicle growth & ovulation
(e.g.)
Estrogens & GnRH
Oral Progestins: Melengestrol Acetate (MGA)
Ear implants Crestar
Intravaginal Devices
PRID CIDR-B DIB TRIU-B CUE-MATE
Program with MGA for estrus synchronization
MGA Day 0 14
PGF ED + AI
31/33
(17/19 days)
MGA = melengestrol acetate @ 0.5 mg/heifer/day
NO AI
Modified MGA program (MGA select)
MGA Day 0 14
PGF ED + AI
33
NO AI
GnRH
26
Wood-Follis et al., 2004
MGA/PGF vs. MGA Select (ED + AI for 6 days)
80 93 80 96
0
10
20
30
40
50
60
70
80
90
100
MGA/PGF MGA select
Wood-Follis et al., 2004
66 67 63 82
0
10
20
30
40
50
60
70
80
90
MGA/PGF MGA select
N = 124
Estrus rate Pregnancy rate
Anestrus Cycling
* *
Increase estrus detection rate
– Aggressive estrus detection
– Increased frequency of observation
– Use of estrus-detection aids
Tail paint, Kamar, electronic aids
Shortening the luteal phase
(e.g.)
ProstaglandinF2
Simulating the luteal phase
(e.g.)
Progesterone
We used them in combination for TAI
Controlling the estrous cycle
Controlled follicle growth & ovulation
(e.g.)
Estrogens & GnRH
17
Benzoate
Valerate
Cipionate
Days after treatment
1 2 3 4 5 6 7 8 9
Plasma concentrations
TAI protocol (Progesterone & Estrogen)
Insert CIDR
Give
1 or mg EB
o 5 mg E-17B
Remove CIDR
Give PGF
1 mg EB TAI
DAY 0 7 9 10
MON am
TUE am
WED pm
THU FRI SAT SUN
EB or 17B
CIDRi
CIDRr
PGF
EB TAI
TAI protocol-Schedule (Progesterone & Estrogen)
Pregnancy rate in heifers treated with E17B or EB
n = 1428 heifers
65
5659
46
0
10
20
30
40
50
60
70
80
90
100
%
E17B BE
Cyclic
Acyclic
Colazo unpublished
TAI protocol (Progesterone & Estrogen)
Insert CIDR
Give
5 mg E-17B
Remove CIDR
Give PGF 0.5 mg ECP
TAI
DAY 0 7 9 10
PREGNANCY RATES
Colazo et al., 2003
63.3 64.6 63.1
0
10
20
30
40
50
60
70
80
ECP0 (n=98) ECP24 (n=99) EB24 (n=103)
Pregnancy rate for cattle inseminated 24 versus 36 h after second EB treatment
Colazo et al., 2005
49.1
69.8
0
10
20
30
40
50
60
70
80
24 h (n=57) 36 h (n=53)
Some commercially available GnRH products
Fertagyl (Merck Animal Health)
Fertiline (Vetoquinol)
Factrel (Pfizer Animal Health)
Cystorelin (Merial)
Induced ovulation
New follicle growth
CL regression and
Follicle maturation
Synchronized
Ovulation
GnRH GnRH PGF AI
7 d 16 h 2 d
D 0 D 7 D 9 D 10
How Ovsynch works?
Pursley et al., 1995
Cosynch
Second GnRH given at time of AI
Advantage: Reduced handling
Possible disadvantage: Delayed ovulation
GnRH GnRH PGF AI
7 d 0-12 h 2 d
D 0 D 7 D 9 D 10 GnRH +
Pregnancy Rates (%)
Geary et al., 2001
0
10
20
30
40
50
60
Cosynch Ovsynch
n = 360 n = 392
54% 52%
Pregnancy rates to AI in cows and heifers after estrus or Ovsynch
IDE% OVS/TAI% P
Cows 39 (154) 38 (156) >.10
Heifers 74 (78) 35 (77) <.01
P <.01 >.10
Pursley et al. (1997) JDS 80:295
Ovsynch/Timed AI is not effective in heifers
Cosynch plus CIDR or PRID
GnRH PGF GnRH&AI
56-60 h
D 0 D 7 D 10
CIDR or PRID
In
D 0
Out
D 7
Pregnancy rate
Category Cosynch CIDR+Cosynch
Cows n = 71 n = 77
45.1% 42.9%
Heifers n = 23 n = 25
39.1%a 68.0%b
ab (P<0.05).
Martinez et al., 2002
MON am
TUE am
WED pm
THU FRI SAT SUN
GnRH
CIDRi
CIDRr
PGF
GnRH& TAI
TAI protocol-Schedule (7d Cosynch & CIDR)
Experimental Design - 5 d vs 7 d Cosynch
GnRH PGF2α
GnRH
7 d CIDR
5 d CIDR
PGF2α
d -7
d -5
d 0 GnRH
+ AI
60 h
d 0
72 h
Day et al., 2006
0
10
20
30
40
50
60
70
80
Jackson Belle Valley Overall
7-d CIDR 5-d CIDR
Timed AI Pregnancy Rate 5 d vs 7 d Cosynch
Pre
gn
ancy
Rat
e, %
Trt, P<.03; TrtxLoc, P=.08
(n=150) (n=250) (n=400)
Day et al., 2006
53% 73% 58% 61% 56% 65%
TAI Pregnancy Rate
0
10
20
30
40
50
60
70
80
90
100
%
P
r
e
g
n
a
n
t
CO-Synch 5d CIDR
CO-Synch 7d CIDR
a, b Effect of TRT P < 0.03
a
b
120/201 100/204
Experimental Design – Modified 5 d Cosynch
GnRH
5 d PRID
PGF2α
d -5 d 0
72 h
Colazo and Ambrose, 2011
GnRH
+ AI
5 d PRID
PGF2α
d -5 d 0
Timed-AI Pregnancy Rate
0
10
20
30
40
50
60
70
80
905-d Cosynch PRID5-d Modified Cosynch PRID
Trt, P >0.05 Treatment
n=28 n=28
Pre
gnan
cy R
ate,
%
Colazo and Ambrose, 2011
MON am
TUE am
WED am
THU am
FRI SAT SUN
GnRH
PRIDi
PRIDr
PGF
PGF GnRH& TAI
TAI protocol-Schedule (5d Cosynch & PRID)
Timed-AI programs: Overall results
Studies published between 2000 and
2006
Treated beef heifers: 3109
GENMOD en SAS
Pregnancy rate: 53.9 %
Range: 47,3 % to 70,0 %
n = 3110 heifers
56*
49
0
10
20
30
40
50
60
70
Cyclic Acyclic
P < 0.01
Timed-AI programs (Cycling vs. anestrus)
26%
Calving distribution of 90 beef heifers all bred on a single day
0
2
4
6
8
10
12
14
No
. of
calv
ing
s
270 272 274 276 278 280 282 284 286
Gestation length (days)
Reuter and Rinette, 2009 N = 90
Groups CIDR MGA
Control CIDR +E/P +E/P/E MGA +E/P +E/P/E
Preg. to 1st AI (%) 45.2ab 47.3a 49.5a 33.3b 54.8a 45.2ab 48.4a
42 44 46 31 51 42 45
Estrus rate (%) 88.2ac 91.8ab 95.7a 95.2a 83.3bc 84.3c 77.1c n 45/51 45/49 45/47 59/62 35/42 43/51 37/48
Conception rate (%) 62.2ab 64.4ab 73.3a 59.3b 40.0c 53.5bc 54.0bc n 28/45 29/45 33/45 35/59 14/35 23/43 20/37
Pregnancy rate (%) 54.9ab 59.2ab 70.2a 56.4ab 33.3c 45.1bc 41.7bc n 28/51 29/49 33/47 35/62 14/42 23/51 20/48 TAI & Rebreeding 75.3ab 78.5ab 84.9ac 71b 69.9b 69.9b 69.9b
abcdPercentages are different (P<0.05)
Resynchronization of timed inseminated heifers with a used CIDR or MGA and E/P
983 beef heifers TAI over 3 days
All received a used CIDR device
336 heifers reinseminated over 5 days (78.2%)
542 pregnant to TAI (55.2%) and 232 pregnant to re-insemination
Overall PR of 78.7%
Resynchronization of heifers with a used CIDR (12,13 or 14 d after AI)
Timed-AI programs: Cost per pregnancy based on 100 heifers
CIDR/EB CIDR/OVS CIDR/COS7 CIDR/COS5 CIDR/COSM5
$ 26.5 $ 30.0 $ 30.0 $ 35.0 $ 26.5
$ 300 $ 300 $ 240 $ 300 $ 240
$ 2500 $ 2500
$ 2500
$ 2500
$ 2500
65% 55% 50% 65% 60%
$ 83.8 $ 105.5 $ 114.8 $ 96.9 $ 89.8
Drugs
Labour
Semen + AI
Per Preg
PR
May, 2004
THANK YOU !
Marcos G Colazo Research Scientist, Alberta Agriculture & Rural
Development
Edmonton, Alberta, Canada E-mail: marcos.colazo@gov.ab.ca; mgcolazo@yahoo.com
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