Genetic parameters for EGG and related characteristics of White Leghorn hens in a subtropical environment

Estimates of heritability and phenotypic and genetic correlations between e gg number, weight, specific gravity, mass, and estimated shell weight were obtained, along with phenotypic and genetic correlations of specific gravit y and weight with body weight, weight change, metabolizable energy intake, residual feed consumption, and weight and age at sexual maturity. Data were from 350 White Leghorn hens by 50 sires and 175 darns. Heritabilities of t he egg traits ranged from 0.20 to 0.55, increasing with age of bird from 26 to 54 weeks of age. Their standard errors ranged from 0.07 (all data) to 0 .17 (26 to 29 weeks). Phenotypic correlations ranged from 0.80 to -0.13, an d genetic correlations from 0.91 to -0.27, depending on egg trait. The high est phenotypic and genetic correlations were between egg number and mass. G enetic correlations for specific gravity and estimated shell weight were, w ith body weight, -0.02 and 0.56; weight change, 0.29 and 0.44; daily metabo lizable energy intake, -0.10 and 0.33; residual consumption, -0.16 and 0.11 ; age at sexual maturity, -0.61 and -0.46, and weight at sexual maturity, 0 .02 and 0.63. Results should contribute to the design of efficient selectio n programs for economically important traits in hens.