impact of stocking density and group size in enriched cage housing on hen behavior, welfare and...
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Impact of Stocking Density and Group Size in Enriched Cage Housing on Hen Behavior,
Welfare and Performance
Tina Widowski1; Linda Caston1; Steve Leeson1, Leanne Cooley2; Stephanie Torrey3; Michele Guerin4
1Departments 1Animal & Poultry Science and 4Population Medicine
University of Guelph 2L.H. Gray and Son Limited
3Agriculture and Agri-Food Canada (AAFC)
Canada
Enriched Cages
• Provide the hygiene and health benefits of conventional cages (Tauson, 2005)
• Production comparable to conventional cages• Perches and more space increase bone strength• Furnishings support some of the behavior
patterns shown to be important to hens
Source: Manitoba Egg Farmers
Source: LayWel Report
Enriched Cages
• Earliest models held small groups of hens provided nest box, perches, and box of litter for scratching and dustbathing
• More recent trend is to increase group size and replace nest box with curtained area and replace litter box with a mat sprinkled with feed
Source: Manitoba Egg Farmers
Enriched Cages
• Sizes of cages and colonies (Laywel 2007)– Small up to 15 hens– Medium15-30 hens– Large> 30 hens up to ~ 60 or more
• Larger cages provide more total space but may increase risk feather pecking, increased competition and higher mortality in larger groups (Wall 2011)
• Proposed industry changes in North America include period of incremental increases in space allowance
Enriched Cages
• Sizes of cages and colonies– Small up to 15 hens– Medium 15-30 hens– Large> 30 hens up to ~ 60 or more
• Larger cages provide more total space but may increase risk feather pecking, increased competition and higher mortality in larger groups (Wall 2011)
• Proposed industry changes in Egg Bill include period of incremental increases in space allowance
Group Size and Space
• When group size increases the total area and the amount of free space increases
• Hens tend to synchronize activities and cluster together
X 4 =
Objectives
To determine the effects of space allowance and cage size on production, welfare and behavior measures of laying hens housed in two sizes of enriched colony cages
• 1218 Lohman Select Leghorns (LSL)-Lite• Farmer Automatic ‘Enrichable’ Enriched Cage• 2 x 2 factorial experiment• 2 cage sizes:
Large= Standard Commercial Model (358x122cm) Small= Custom built (178x122cm)
• 2 densities:
High= ~520 cm2/hen
Low= ~748 cm2/ hen
(total floor space allowance)
Methods
• Cages were distributed between 2 rooms – 3 tiers, 2 rows of cages in
each room
• Birds were beak treated at the hatchery and reared in standard rearing cages at the research farm
• Housed in laying cages at 18 weeks of age
Methods
Two Rooms Each room holds 6 “Large” and 6 “Small”
Methods
Large Cage
Small Cage
Nesting Area
Scratch Area
Scratch Area
20 g feed delivered through auger 10 times per day
Housing Density # Hens per Cage
# Reps
Total birds
LargeFurnished
High 80 6 480
LargeFurnished
Low 55 6 330
Small Furnished
High 40 6 240
Small Furnished
Low 28 6 168
Conventional 465 cm2 5 20 100
Group Sizes
Cage Floor Space
Cage Space
Nest Scratch Perch
LargeHigh
516(80)
559(86)
70(11)
31(4.8)
12(4.5)
SmallHigh
522(81)
560(85)
70(11)
62.5(9.6)
11(4.3)
LargeLow
750(116)
814(126)
102(15.8)
45.5(7)
16.8(6.6)
SmallLow
746(115.6)
800(124)
101(15.6)
89.3(13.8)
15.5(6)
Space Allowances in cm2(in2)
Production measures– Hen-day egg production from 20 weeks to end of lay
– Egg weights and shell strength (deformation) collected from sample of eggs once per ~28 days
– At 37, 43, 49, 56 and 70 weeks of age feed intake was measured over 2 day period
Methods
Hen Day Egg Production High Density and Low Density Cages
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
38
39
40
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42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
70
75
80
85
90
95
100
Age in Weeks
High Density = 80 in2/hen (93.0±.14%)Low Density = 116 in2/ hen (94.4 ±.15%)Age P<0.01Density NS
Feed Intake (g/bird/day)*
Age Cage Density Cage Size
High Low Large Small Pooled SE (±)
37 117.6 118.8 115.8 120.6* 4.6
43 111.0 110.3 107.9 113.3* 4.2
49 99.5 101.5 99.7 101.3* 6.3
70 109.7 111.3 105.6 115.4* 5.5
*Significantly higher feed intake in the small cages/group sizes
Egg Weights (g) Cage Density Cage Size
Age (wks)
High Low Large Small Pooled SE
21 50.9 50.9 51.1 50.1 1.2
29 57.1 57.5 57.1 57.4 .91
33 59.2 59.6 59.6 59.2 .96
41 60.3 60.1 60.2 60.2 1.07
49 61.6 61.7 61.6 61.7 1.12
57 62.1 61.8 62.3 61.7 .90
65 63.2 63.3 63.0 63.6 .92
69 63.6 63.7 63.6 63.6 .95
No Effect of Cage Size or Density
Egg Deformation (μm)
Cage Density Cage Size
Age (wks) High Low Large Small Pooled SE
21 17.8 18.3 17.7 18.4 1.1
29 19.6 19.9 19.9 19.9 0.78
33 20.2 20.0 20.1 20.1 0.73
41 20.5 20.3 20.4 20.4 0.65
49 21.9 21.6 21.5 21.9 0.70
57 23.1 22.2 22.8 22.8 1.32
65 23.5 23.3 23.5 23.3 0.92
69 22.4 22.4 22.6 22.2 1.0
No Effect of Cage Size, Cage Density, P=.0535
Welfare Measures• Mortality (cumulative)
– cause of death determined from necropsy
• At 30, 50, and 60 and 70 wks of age 20% birds from each cage were sampled– Body weight– Feather condition– Cleanliness– Keel score– Foot health
Methods
Mortality
Cage Density Cage Size
High Low Large Small Pooled SE
4.79 4.35 4.47 4.67 1.73
Cumulative % to 72 weeks of age
No Effect of Cage Size or Density
Significant effects of tier – birds on middle level had highest mortality (P<0.01)
Body WeightCage Density Cage Size Furnish’d
Age (wks) High Low Large Small Pooled SE
Mean
50 1715 1757 1732 1733 63.3 NS
60 1722 1726 1720 1732 75.4 NS
70 1736 1726 1719 1756 87.3 NS
Coefficient of Variation
50 9.2 10.9 9.7 10.5 NS
60 11.9 10.4 11.4 11.1 NS
70 17.1 17.0 15.2 20.6 NS
No Effect of Cage Size or Density
Feather Scoring
Rump
Belly
BackHead
Neck
0 = Feathers intact
1 = Some feather damage
2 = Bare areas
Feather Scoring
Effect of Stocking Density on Feather Scores
High Density = 80 in2/hen Low Density = 116 in2/ hen
Feather score deteriorated in all birds over time (P<0.001)
Feather score poorer in high density cages over time (P<0.001)
Effect of Stocking Density on Cleanliness Score
High Density = 80 in2/hen Low Density = 116 in2/ hen
0-3 increasingly dirty
Cleanliness score deteriorated in all birds over time (P<0.001)
Cleanliness score poorer in high density cages over time (P<0.03)
Behavior
• Nesting- enough nest space for all hens?
• Foraging – pecking and scratching on mat, feeder, floor
• Dust bathing on scratch mat or wire floors
• Perching
Methods
• Grad student Michelle Hunniford• Where the eggs were laid• When the eggs were laid• Aggression around nesting
Nesting
Location• Methods:
– During daily egg collection location of all eggs were recorded
Scratch AreaNest Area
NEST BOX SCRATCH AREA0
10
20
30
40
50
60
70
80
90
100
% Eggs Laid in Nest and ScratchHigh Density and Low Density Cages
70cm2/bird100cm2/bird
Per
cen
tag
e Pnest = 0.925Pscratch = 0.912
NEST BOX SCRATCH AREA0
10
20
30
40
50
60
70
80
90
100
% Eggs Laid in Nest and Scratch Large and Small Cages
SMALL LARGE
Pe
rce
nta
ge
*
**
*P < 0.01** P < 0.001
Timing
• Methods (2 ways)1. Digital video recording during 14 hrs of day
2. During live observations of nesting behaviour (5 -11 am)
– Number of eggs recorded every 15 minutes– Analyzed for differences in location over time
5:00-6:00 6:00-7:00 7:00-8:00 8:00-9:00 9:00-10:00
10:00-11:00
0
10
20
30
Time Eggs Laid in Nest and Scratch
High Density and Low Density Cages
High NestLow NestHigh ScratchLow Scratch
Time Interval
Pe
rce
nt
5:00-6:00 6:00-7:00 7:00-8:00 8:00-9:00 9:00-10:00
10:00-11:00
0
5
10
15
20
25
30
Time Eggs Laid in Nest and Scratch
Large and Small CagesLarge NestSmall NestLarge ScratchSmall Scratch
Time Interval
Pe
rce
nt
Aggressive Behavior
• At 69 weeks hens were observed by systematically scanning cages 5 times during 4 observation periods in the morning from lights on to 11 am
– Threats– Aggressive pecks
Threat Peck Total0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
Average Aggressive Behaviors per Bird in Large and Small Cages
LargeSmall
Ag
on
isti
c B
eh
av
iou
rs p
er
BIr
d
*
*
**
Behavior
• Slightly less time spent foraging in High Density
• No effects of density on dust bathing• Majority was on wire, not scratch mat
• Auger activation stimulated more foraging
• Feeder chain activation stimulated dustbathing and foraging
Summary
• No density effect on egg production, egg weights, egg shell strength, feed intakes, body weight or uniformity
• Higher feed intakes in groups of 28-40 compared to larger cages/group sizes of 55-80
• No effect of size or density on total cumulative mortality
• At 60 weeks – more cracked and dirty eggs from scratch area in high density cages
Summary
• Feather scores were poorer in high density cages
• Birds were slightly dirtier in high density cages
• Few effects of density on the behavior that we measured
• Cage/group size but not density affected nest use, timing of eggs laid and aggression around nesting
Acknowledgements
Funding for this project was provided by • Ontario Ministry of Agriculture, Food and Rural Affairs• Egg Farmers of Canada• Poultry Industry Council• Clark Ag-Systems/Farmer Automatic
• We are grateful for the assistance of Michelle Edwards for statistical support, Arkell Poultry Research Station staff and the many, many graduates who helped with data collection