Divergent selection for body weight and yolk precursor in Coturnix coturnix japonica. 3. Correlated responses in mortality, reproduction traits, and adult body weight.

Egg production, mature body weight, egg weight, yolk weight, fertility, hatchability, and mortality during the early growing period were compared in strains of Japanese quail. The strains were either a randombred control (R1) that served as the base population or strains divergently selected for high (HW) or low (LW) 4-week body weight or high (HP) or low (LP) plasma phosphorus (yolk precursor) early in the laying period. Changes in 4-week body weight in HW and LW were associated with corresponding changes in mature body weight, yolk weight, and total egg weight. Egg production decreased in HW, but there was no significant change in LW. Mortality increased in LW and decreased in HW. Egg production of HP declined at a rate similar to that observed in HW. No other consistent significant changes occurred in the phosphorus strains. Fertility and hatchability did not exhibit significant strain differences in the fifth generation of selection.