impact of stocking density and group size in enriched cage housing on hen behavior, welfare and...

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

41

42

43

44

45

46

47

48

49

50

51

52

53

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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