Influence of later exposure to perches and nests on flock level distribution of hens in an aviary system during lay.

Aviaries provide hens with many resources, but birds must develop motor and cognitive skills to use them properly. Introducing birds to aviaries at older ages has been reported to result in less use of perches, nests, and vertical space, which can reduce productivity and hen welfare. The objectives of this study were to examine (1) how enrichment influenced distribution of hens in the aviary during the day and (2) how enrichment influenced the distribution and roosting substrate of birds at night. Hy-Line W36 pullets were raised in floor pens before moving to laying aviaries (100 hens/aviary unit × 4 units/treatments). Control (CON) pullets were placed into aviaries at 17 wk of age (WOA). Floor (FLR) and enriched (ENR) pullets remained in floor pens until 25 WOA, and ENR birds were provided with perches and nests at 17 WOA. Birds were counted in tiers and litter areas of the aviary at morning, midday and evening at 36 and 54 WOA. Data were analyzed using generalized linear mixed models in R statistical software. At 36 WOA, ENR and CON birds occupied aviary areas at similar rates but differently from FLR birds. For example, in the morning 34% of CON hens and 30% of ENR hens occupied the highest tier compared to 15% of FLR hens (P < 0.01). At midday, 57% of CON and 57% of ENR birds were counted in litter compared with 77% of FLR birds (P < 0.01). In the evening, CON and ENR hens moved to the top tier of the aviary in greater numbers than FLR hens (22 and 17%, respectively, vs. 7%, P < 0.01). At 54 WOA, differences between FLR hens and CON/ENR hens were less pronounced, suggesting FLR hens were adapting to the aviary. Overall, we conclude that birds exposed to aviaries at 25 WOA can adapt to aviary systems, but take more time to do so than birds exposed to aviaries or vertical enrichment at 17 WOA.