Direct and correlated responses to selection for 4-week body weight in two lines of Japanese quails
Abstract. Data on 29,411 quails of two selected lines along with a control line were examined over nine generations. Significant genetic gains/generation for 4-week body weight were realized in the two strains (3.70 and 3.10 g). Significant correlated genetic changes were also observed in early body weights (day-old to 3-weeks) as well as in 16-week body weight. Egg number and sexual maturity did not show any significant response while egg weight and egg mass showed desirable genetic gains. Natural selection did not seem to exert any effect. Inbreeding levels of 0.32 to 0.43 % per generation did not appear to be of any significance in affecting the response. Realized heritabilities (0.21–0.24) were reasonably consistent between sexes and matched fairly well with the nine-generation pooled sire-component heritabilities of 0.20 ± 0.04 and 0.25 ± 0.04 in the two lines. There was evidence of maternal effects as indicated by excess of dam- over the sire-component heritability. Time-trend in heritabilities was non-significant. There was good agreement between the predicted and realized genetic gains.