Effect of Divergent Selection for Body Weight on Egg Production and other Reproduction Traits in Japanese Quail

The aim followed in the present research was to investigate the effect of nine generations of divergent selection on some reproductive and egg production traits in Japanese quail. The results indicated that selection for 4-week body weight، increased the age at sexual maturity of HW and of LW lines، in comparison with control، for about 7 and 3 days، respectively (P<0. 05). At the ages of sexual maturity، there weren’t significant differences observed within the selected lines (P<0. 05)، but these lines were significantly different from control. Body weight at sexual maturity was higher in HW line than in LW and in C. The differences between lines were significant (P<0. 05). Body weight at sexual maturity and average egg weight at different productive stages increased in HW in comparison with control (P<0. 05). This was while، percentage egg lying at the point of sexual maturity was higher in LW than in control (P<0. 05). Total number of eggs laid was higher in LW than in HW and in control while the difference being significant only with HW. The highest percentage of egg-laying was recorded within 3-6 pm in any of the three lines. Peak egg production occurred during the second month. It can finally be concluded that because of the interrelated response between body weight and reproductive traits، it’s important to consider the reproductive and safety traits beside growth traits in selection programs.