Inheritance of body weight and body weight ratios and their relationship with economic traits in White Leghorn chicken

This study was carried on two selected strains and one control line of White Leghorn chickens comprising of 1733 pullets. Body weight of selected lines was significantly higher than the control line from day-old to 20 weeks of age. Heritability estimates were generally much higher from day-old to 8 week of age than from 16 to 40 week of age. The heritability of body weights ranged from 0.18±0.11 to 0.83±0.22 and of body weight ratios ranged from 0.02±0.06 to 0.72±0.23 across ages and strains. Age at sexual maturity and egg number had low to moderate while egg weight had high heritability. The different derived traits, in general, had low heritability. Genetic correlation of early body weights with egg number, egg mass and egg weight were positive while these with age sexual maturity and rate of lay were negative. In general, genetic correlation of body weight with egg production efficiency, efficiency index, egg mass per functional day and egg weight percentage of body weight were positive. The genetic correlation estimates indicated that selection for early body weight is expected to lead to improvement in the overall productivity of laying birds.