Comparision of Direct and Indirect Response to Selection for Breast Weight in Japanese Quail

This study was carried out to investigate the direct and indirect responses to selection for fourweek body weight (4 week body (wk BW)) and fourweek breast weight (4 week breast weight (wk BRW)) and to determine the genetic contribution of reminder founders to the last generation. A total number of 351 birds were equally allocated to three lines, including two selected lines (S1 and S2 for BW and breast weight, respectively) along with a control (C) line. Total net genetic improvement for BW and BRW in S1 and S2 lines were 31.6, 7.6 and 28.0 and 7.3 g, respectively. Genetic correlations between 4 wk BW and carcass traits (0.85 to 0.95) and phenotypic correlations (0.43 to 0.93) were positively high in S1 and S2 lines. The mean percentage of inbreeding for population and inbred birds in S1 and S2 lines were 0.95, 7.75 and 0.64 and 11.3, respectively. The number of retained founders to the last generation of S1 was more than S2. However, more balance genetic contribution to the last generation was outlined by the founders in S2 line. The BW can be used as a selection criterion to improve the carcass traits because there is a strong correlation between BW and carcass traits, selection for BW is easier to record and also its improvement costs are lower than selection for BRW. Meanwhile, long term response to selection is needed to preserve alleles from the lowest contributed founders.