Divergent Selection for Body Weight and Yolk Precursor in Coturnix coturnix japonica.: 11. Correlated Responses Over Thirty Generations

Abstract

Japanese quail lines were divergently selected for 4-wk BW (HW and LW lines) and plasma yolk precursor [total plasma phosphorus (TPP); HP and LP lines] for 30 generations. The base population was a randombred control line (R1) that was maintained along with the selected lines. Sublines were established from the ninth selected generation of HW by continuing to select males for increased 4-wk BW and selecting females for increased (HW-HP line) or decreased (HW-LP line) TPP. Correlated responses over the entire selection period were measured.Egg production of HW, LW, HP, and HW-HP declined over generations. There was a positive quadratic component to the change in HW indicating that the change in egg production over generations was decreasing. There was no significant change in egg production of LP. Number of ovarian follicles in rapid development increased in LP and decreased in LW and HP, Total follicular weight increased in HW and LP and decreased in LW. Production of abnormal eggs increased over generations in HW and HW-HP.Body weight at the beginning and end of the laying period increased in HW, HW-HP, HW-LP, and LP and decreased in LW. Egg weight increased in HW and HW-HP and decreased in LW and LP. The increase in egg weight of HW was due to a disproportionate increase in shell and yolk. Wet weight of the liver increased in HW and decreased in LW and HP. Dry liver weight decreased in LW, HP, and LP. Mortality to 4 wk of age increased in LW, HP, and LP.