Effects of different laying management strategies on subsequent fear responses in aviary laying hens

1. This study investigated subsequent effects of different floor laying management strategies on the fear response of laying hens housed in two different aviary styles (Big Dutchman® NaturaStep and Natura60).2. Tonic immobility (TI) responses in hens were measured as reactions to a ground robot moving or a human walking on the litter area, compared with control/standard practices. Management strategies were started at 16 weeks of age (WOA) and ended at 32 WOA.3. Twenty birds from six groups (three treatments × two aviary styles) were chosen at random for TI testing at 36, 44, and 55 WOA. For this purpose, randomly collected hens were gently taken out of their pens and transported to the testing room using a mobile multi-tier cage. Each individual hen was placed gently on its back on a flat surface, and TI was induced by gently pressing on its breast. If TI was induced, the length of time to the first head movement, the latency to return to an upright position, and the number of attempts to induce TI were recorded.4. Aviary style significantly affected the length of time to first head movement (p < 0.05). Hens at 55 WOA remained in TI significantly longer than those of earlier ages (p = 0.004). There were no significant effects of stressors/management strategies or aviary style on time to upright position. The average number of attempts required to induce TI was similar for all birds.5. The results indicated that neither stressors or aviary styles had any significant effects on the traits investigated. Older hens tended to exhibit higher levels of fearfulness compared to younger hens.