Daily behavioral patterns of laying hens kept in a multi-tier system across different microclimatic conditions.

The present study compared the daily behavioral pattern of laying hens in a multi-tier system at different months representing different microclimatic conditions. The behavior at the different levels (ground, first, second and third tier) of 450 laying hens in two pens was video recorded three days per month and then scored every 15 minutes. On the ground, the rate of pecking hens was lower in January compared to March and June, while the rate of preening and ground scratching hens was higher (P < 0.001); in March, both the rate of dustbathing hens (P = 0.004) and the occurrence of piling (P < 0.001) showed a peak. Across the three tiers, the rates of perching (P < 0.001) and preening hens (P < 0.001) were higher in January compared to March and June, while the rate of hens pecking the tier was lower (P < 0.001). Finally, the rate of hens resting on the tiers was higher in January compared to March (P = 0.01) with intermediate values in June. Overall, laying hens exhibited a functional space use of the multi-tier system, expressing species-specific behaviors according to available resources and equipment and consistent daily behavioral pattern across different microclimatic conditions, despite showing month-specific differences at certain hours. Some changes in the behavioral patterns at the different tiers across the different microclimatic conditions were possibly dependent on the corresponding different number of animals, i.e. a different vertical distribution of animals depending on microclimatic conditions.