The effect of different cage densities on selected stress and welfare indicators in brown and white laying hens

This study investigated the impact of different cage densities (750 cm 2 /hen, 535 cm 2 /hen, and 375 cm 2 /hen) on stress and welfare indicators in brown (Hyline Brown, HB) and white (Isa Tinted, IT) laying hens. The research focused on evaluating feather, health, and body condition scores, along with the heterophil-to-lymphocyte (H/L) ratio, as indicators of stress and welfare. Our results revealed a significant effect of cage density on feather scores, with higher densities correlating with increased feather loss across all body regions ( P < 0.01). Furthermore, elevated cage densities were associated with a higher incidence of injuries in the cloaca and foot regions, as well as poorer body condition scores ( P < 0.01). Notably, the HB hybrid consistently exhibited superior welfare indicators compared to the IT hybrid, as evidenced by higher feather scores, and higher body condition scores. With the increase in cage density, an increase in the H/L ratio was observed, and accordingly, an increase in stress intensity was determined ( P < 0.01). These findings underscore the complex relationship between cage density, genotype, stress, and welfare outcomes in laying hens, emphasizing the need for further research to elucidate these interactions and develop targeted strategies for improving laying hen welfare in commercial production systems.