Impact of cage stocking density on egg laying characteristics and related stress and immunity parameters of Japanese quails in subtropics

The aim of this study was to investigate the effects of different cage stocking densities on egg production parameters, as well as related stress and immunity indices in Japanese quails under subtropical Egyptian conditions. Two hundred and sixteen birds of Japanese quail at 14th week of age were used in this experiment. The birds were divided randomly into three groups: 60, 72 and 84. Each group subdivided into 4 replicates, where the cages' floor spaces were 200 (S₁), 167 (S₂) and 143 (S₃) cm²/bird, respectively. Birds housed at 200 cm²/bird (S₁) had superior fertility (fertility % (p = 0.013) and hatchability % (p = 0.041)), egg production (egg weight (p = 0.034) and egg mass (p = 0.001)) and immunity parameters (higher geometric mean of antibody titres against Newcastle disease virus, p = 0.024). Furthermore, they had higher internal egg quality score: albumen height (p = 0.003), yolk height (p = 0.023), yolk index (p = 0.006) and Haugh unit (p = 0.035). Birds housed at 143 cm²/bird (S₃) had the lowest total leucocytic count and lymphocyte % (p = 0.022), but the highest H/L ratio (p = 0.001). Corticosterone concentration was lower in S₁ group (p = 0.031) than that in groups housed at higher densities. Japanese quail housed at high densities revealed drop in fertility, hatchability, production and immunity parameters, indicating a detrimental effects on both welfare and economic income.