Restricted feeding could enhance feed conversion ratio and egg quality of laying Japanese quail kept under different stocking densities.

Impacts of different stocking densities and feed restriction on egg production and quality and blood biochemicals of laying Japanese quail (Coturnix coturnix Japonica) were studied. A total number of 360 adult Japanese quails were used in an experiment, including two stocking densities (300 and 200 cm2/bird) and four feed restriction levels (ad libitum, 25, 30 and 35 g/day/bird). As a result of this study, feed restriction (30 g/bird/day) enhanced most of egg production traits and improved hatchability. Albumen and egg shell thickness showed the highest values when birds fed ad libitum and 35 g/bird/day. Blood total protein, albumin, Aspartate Aminotransferase (AST) and cholesterol were higher in quails housed at 200 cm2/bird than those kept at 300 cm2/bird. The highest values of blood total protein, albumin, AST and cholesterol were found in quails fed ad libitum. Activity of superoxide dismutase was the highest estimate when birds stocked at 300 cm2/bird and fed ad libitum or 25 g/day. Conclusively, decreasing space per bird had a negative effect on performance. Feed restriction can achieve a better feed conversion ratio (FCR).