SELECTION FOR EGG-PRODUCTION .2. CORRELATED RESPONSES IN SEXUAL MATURITY, EGG WEIGHT AND BODY-WEIGHT OF 4 STRAINS OF WHITE LEGHORN

Four strains of White Leghorn were subjected to Osborne index selectio n for egg production up to 280 days of age for 4 generations. Correlat ed responses in sexual maturity, egg weight and body weight along with the selected strains. Egg number was negatively correlated with sexua l maturity, egg weight and body weight at 40 weeks in all the 4 strain s; whereas with body weight at 20 weeks showed positive correlation fo r IWN strains. Sexual maturity was positively correlated with egg weig ht but it was in differential direction and magnitude with body weight s. Egg weight and body weights at 20 and 40 weeks were positively corr elated. Similarly strong positive association between body weight at 2 0 and 40 weeks of age was recorded. The realized genetic correlated re sponse per generation showed significant reduction in age of sexual ma turity in all the 4 strains (-2.9 to -3.7). Negative regression coeffi cients for egg weight (-0.3 to 0.5) as well as for body weight at 40 w eeks (-4.1 to -11.9) were recorded. Body weight at 20 weeks showed pos itive correlated response (10.3 to 33.3). Realized genetic responses w ere higher than the predicted responses. The positive response to egg number was partly associated with early age at first lay and smaller e gg size.