Genetic study on body weights of Japanese quails

The data on body weights of Black and Brown Japanese quails under selection for higher body weights over four generations were analyzed. The overall least squares means for body weights at hatch, 1, 2, 3 and 4 weeks of age were 9.75, 37.09, 77.55, 126.41 and 170.95 g, respectively. The effect of strains and generations was significant on body weights at all the ages, while the influence of sex was evident from 2 to 20 weeks of age. Hatch effect was significant on body weights up to 4-weeks age only. The birds of 7^th generation exhibited highest body weights and sexual dimorphism was in favour of females. Medium to high heritability estimates were obtained for body weights from 1 to 4 weeks of age in Black and Brown Japanese quails by half-sib and as well as full sib methods. The estimates based on dam component were higher than those based on sire component for body weights at majority of the ages. The genetic, phenotypic and environmental correlations among the body weights varied from moderate to high in magnitude and positive in direction. The response to selection in body weight at 4-weeks age varied from 6.03 to 30.93 g in Black males; 6.84 to 14.24 g in Black females; 2.67 to 6.90 g in Brown males and 2.20 to 6.41 g in Brown females. The cumulative response to selection in 5 to 8 generations was 53.31, 40.21, 18.85 and 15.05g in Black males, Black females, Brown males and Brown females, respectively. It could be concluded that considerable improvement has been observed in the body weights of quails through selection.