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Complex rearing aviary design promotes different load bearing activities in laying hen pullets

2021 CPRF
Compared to layer pullets raised in cages, pullets raised in aviaries have stronger bones due to increased opportunity for exercise. Dynamic load bearing exercise engenders osteogenic levels of mechanical strain on the bone, promoting bone formation and enhancing strength. The type of load bearing exercise will impact different bones in the avian skeleton. E.g., wing-assisted activities likely affect the keel bone, which is particularly prone to fractures. Commercial rearing aviaries vary greatly in their structural complexity and offer vastly different experiences for pullets. Especially the brooding phase (BP) differs when chicks are confined within brooding compartments before given access to litter and multiple tiers in the free-run phase (FP). We hypothesised that the prevalence of dynamic load bearing activity (dlb; walking, running, flying, jumping, stepping up/down) as well as wing-involved load bearing activity (wlb; wing-assisted locomotion and wing-flapping) differ between aviary styles as well as between brown (B) and white (W) layer strains. We raised 3 flocks of B Lohmann lite and W LSL-lite pullets in 3 commercial rearing aviary styles. Aviary style 1 (S1; n= 345) offers the least complexity, style 2 (S2; n= 432) intermediate and 3 (S3; n=600) the most, with main differences being the space and complexity of the brooding compartments where chicks spend the first 6 weeks. Live behaviour observations were done at 3 ages during the BP and FP each. Statistical analysis was done in R by applying generalised mixed effect models. Both dlb and wlb were affected by style and strain. During the BP, S3 performed more dlb than S2 and S1 (p<0.001) and W more than B (p<0.001). There was a trend for a higher odds of wlb in S2 and S3 (p=0.07), with no effect of strain. In the FP, there was an interaction of style and strain (p<0.05) with S2W and S3W showing more dlb than any other group. There was a trend of style affecting wlb with S2 showing the highest odds (p=0.07). These results confirm that birds perform more dlb in more complex aviaries and W perform more dlb than B. A2 perform most wlb behaviour. In conclusion, rearing aviary design can promote different dynamic and wing involved load bearing activities, which will have varying affects on bone strength and subsequent fracture risk. We aim to improve laying hen welfare by growing pullets fit for complex free-run housing.
Tags :
aviary design,bone health,laying hens
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PhD Student

University of Guelph

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