Inheritance of body weight,egg weight and age at first egg in white leghorn birds

Abstract

An investigation was carried out to study the inheritance of body weights, age at first egg and egg weight in White Leghorn birds. The data required for the study were collected from two strains of White Leghorns maintained in the Farm under All India Co – ordinated Research Project for Eggs, Mannuthy. The Least squares analysis of variance was carried out to find out the effect of hatches on the traits under study. Since the effect of hatch was significant, the data were adjusted for this effect and utilized to estimate heritability, genetic, phenotypic and environmental correlations among body weights and age at first egg. Hatch effect was not significant for egg weight. The averages for body weights (g) at 20 weeks and 40 weeks, age at first egg (days) and egg weight (g) were 1181.5 + 2.8, 1457.0 + 4.0, 166.0 + 0.30 and 51.7 + 0.10 for N strain and 1245.9 + 5.4, 1518.6 + 5.7, 162.1 + 1.1 and 51.7 + 0.10 for P strain respectively. The heritabilities based on sire, dam and sire + dam components of variance were 0.25 + 0.00, 0.36 + 0.01, 0.31 + 0.01, for body weight at 20 weeks; 0.22 + 0.00, 0.50 + 0.03, 0.36 + 0.00 for body weight at 40 weeks; 0.20 + 0.00, 0.22 + 0.03, 0.21 + 0.00 for age at first egg and 0.43 + 0.00, 0.62 + 0.03 and 0.52 + 0.01 for egg weight respectively. In P strain the respective estimates were 0.25 + 0.02, - 0.19 + 0.12 and 0.03 + 0.04 for body weight at 20 weeks; 0.44 + 0.00, 0.27 + 0.04 and 0.35 + 0.02 for body weight at 40 weeks; 0.06 + 0.00, - 0.11 + 0.04 and 0.00 + 0.02 for age at first egg and 0.28 + 0.01, 0.95 + 0.04 and 0.61 + 0.02 for egg weight respectively. The genetic correlations between body weights at 20 weeks and 40 weeks and between body weights and egg weight were positive, between body weights and age at first egg negative and between age at first egg and egg weight positive. Environmental and phenotypic correlations between the traits were generally of low magnitude.