Effects of rearing with vertical structures on the ontogeny of depth perception in laying hens

Applied Animal Behaviour Science · 2023 · 5 citations

• Biology
• Animal science
• Engineering

Multi-tiered aviary systems provide laying hens with opportunities for species-specific behaviors, including vertical and horizontal movement. However, collisions and failed landings that occur during vertical movement can be associated with injuries. Previous studies suggest that floor rearing of pullets with minimal access to elevated structures may negatively impact adult laying hens’ ability to navigate vertical space. However, it is not clear whether this is due to deficits in physical ability or differences in depth perception. This was investigated in pullets and egg-laying hens using a modified Y-maze task and a visual cliff task at 7–8, 15–16, and 29–30 weeks of age. Dekalb White pullets (N = 450) were reared in three different environments until 16 weeks of age: floor, single-tier aviary, and two-tier aviary. From 16 weeks of age, all birds were housed in a multi-tier aviary. The Y-maze task consisted of two arms that were either a ratio of 1:3 or 1:1 in length. Each bird’s ability to discriminate the different arm lengths was evaluated based on latency to exit and arm choice. The illusion of depth over a plexiglass floor was tested in the visual cliff task at 15, 30, and 90 cm. Birds were given 1.5 min to either leave the start perch by jumping to a platform suspended over the visual cliff, or step down off the perch to the shallow side. Latency to jump to the platform and frequency of looking down over the visual cliff were recorded. There were no main effects of age or rearing treatment on behavior in the Y-maze, with all birds choosing the shorter arm more than chance (p < 0.001). Regardless of cliff height, birds reared on the floor were less likely to cross the visual cliff at 8 and 16 weeks of age than single and two-tier treatment birds (p = 0.01). However, these differences were not observed after they were given experience with elevated structures in the adult aviary. The results of the present study suggest that the lack of exposure to vertical complexity during rearing do not cause long-term detriments to depth perception, but could impact successful engagement with elevated heights (i.e., hesitancy to access vertical structures). Further research is needed to determine the timing, quality, and quantity of elevated height exposure that is needed in the rearing environment to encourage sufficient use of vertical space in the adult aviary for cage-free laying hens.

Enhancing their quality of life: environmental enrichment for poultry

Poultry Science · 2022 · 53 citations

• Business
• Environmental economics
• Environmental resource management

Providing environmental enrichments that increase environmental complexity can benefit poultry welfare. This Poultry Science Association symposium paper is structured around four themes on 1) poultry preferences and affective states 2) species-specific behavior, including play behavior and the relationship between behavior, activity level and walking ability, 3) environmental enrichment and its relationship with indicators of welfare, and 4) a case study focusing on the application of enrichments in commercial broiler chicken production. For effective enrichment strategies, the birds' perspective matters most, and we need to consider individual variation, social dynamics, and previous experience when assessing these strategies. Play behavior can be a valuable indicator of positive affect, and while we do not yet know how much play would be optimal, absence of play suggests a welfare deficit. Activity levels and behavior can be improved by environmental modifications and prior research has shown that the activity level of broilers can be increased, at least temporarily, by increasing the environmental complexity. However, more research on impacts of enrichments on birds' resilience, on birds in commercial conditions, and on slow(er)-growing strains is needed. Finally, incorporating farmers' expertise can greatly benefit enrichment design and implementation on commercial farms.

Pullet Rearing Affects Collisions and Perch Use in Enriched Colony Cage Layer Housing

Animals · 2020 · 13 citations

• Animal science
• Biology
• Fishery

= < 0.001). Rearing in aviaries influences hen behavior out to peak lay for collisions and out to mid-lay for perch height preference in ECC.