Genetic parameters of various economic traits in different generations of synthetic White Leghorn

The data on body weights at 20, 40, 56 and 72 weeks of age, age at first egg, egg production up to 40 and 72 weeks of age and egg weight at 32, 40, 56 and 72 weeks of age on pullets of synthetic White Leghorn belonging to 30 to 40 sires families under long term selection for egg production over five generations were analyzed by least squares analysis techniques. Larger magnitude of heritability estimates for age at first egg was observed in nearly all the generations under study. The heritability estimates were moderate to high for egg production up to 40 weeks, whereas a low to moderate estimates were observed for egg production upto 72 weeks of age. However, all growth and egg weight traits showed moderate to high heritability. The genetic correlations among growth traits were strong and positive. The genetic and phenotypic correlations of age at first egg with body weight and egg production were low positive to negative while the correlations between body weights and egg weights showed positive trend. The genetic correlation of egg production with body weight and egg weight revealed negative association between the traits.