Ali, A. B. A., Campbell, D. L. M., Karcher, D. M. et al. 2019. Daytime occupancy of resources and flooring types by 4 laying hen strains in a commercial-style aviary. Journal of Veterinary Behavior 31, 59-66.
In response to consumer demands and legislative measures for improving hens' welfare, many laying hen producers are replacing conventional cages with aviaries. Aviary resources, such as nest boxes, litter areas, ledges, and perches, are intended to increase the display of natural behaviors. However, commercial laying hen strains have been differentially selected for varying traits including egg quality, feed efficiency, and behavior. Therefore, the assumption that laying hens are using the given resources similarly, irrespective of their genetic strain, may be false. This research examined the influence of laying hen strains (brown hens: Hy-Line Brown, Bovans Brown; white hens: DeKalb White and Hy-Line W36) on resource or flooring substrate occupancy (litter areas, nests, elevated wire tiers, ledges, and perches) inside aviaries during peak lay (25 to 28 weeks of age), and whether this occupancy changed in response to litter access. Live observation and video-recording of hens' distribution among different resources were conducted at 3 different times (morning, midday, and evening) for 3 consecutive days, immediately before (PRE), immediately after (IMM), and 3 weeks after (ACC) hens gained access to litter. Observations were conducted in 16 aviary units; 4 units/strain, 144 hens/unit. Data were analyzed in R using generalized linear mixed model with Tukey's post hoc test and α set at 0.05. More brown hens were in nests than white hens during morning across all periods (PRE; P = 0.002, IMM; P = 0.012, and ACC; P = 0.015), but more white hens were recorded in nests than brown hens during midday of all periods (PRE; P = 0.026, IMM; P = 0.028, and ACC; P = 0.024). More white hens were on litter compared with brown (P = 0.002), particularly when litter was first accessible. White hens occupied the open litter area in larger numbers than brown hens during midday and evening of IMM and ACC periods (P ≤ 0.05). Brown hens occupied the underneath litter area in larger numbers than white hens during midday and evening of the ACC period (P ≤ 0.05). Throughout the day, brown hens occupied wire floors in higher numbers than white hens, whereas the latter occupied both ledges and perches more (all P ≤ 0.05). These strain differences suggest that specific aviary designs may be best suited to specific hen strains.