Direct and correlated responses to selection for 4-week body weight in twolines of Japanese quails

Data on 29,411 quails of two selected lines alongwith a control line were e xamined over nine generations. Significant genetic gains/generation for 4-w eek body weight were realized in the two strains (3.70 and 3.108). Signific ant correlated genetic changes were also observed in early body weights (da y-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 mas s showed desirable genetic gains. Natural selection did not seem to exert a ny effect. Inbreeding levels of 0.32 to 0.43% per generation did not appear to be of any significance in affecting the response. Realized heritabiliti es (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 eff ects as indicated by excess of dam- over the sire-component heritability. T ime-trend in heritabilities was non-significant. There was good agreement b etween the predicted and realized genetic gains.