DIVERGENT SELECTION FOR BODY-WEIGHT AND YOLK PRECURSOR IN COTURNIX-COTURNIX-JAPONICA .12. HETEROSIS IN RECIPROCAL CROSSES BETWEEN DIVERGENTLY SELECTED LINES

A selection experiment was started using Japanese quail to study the g enetics of BW and plasma yolk precursor (measured by total plasma phos phorus; TPP). Lines were divergently selected for 4-wk BW (HW and LW) or plasma TPP (HP and LP). Sublines of HW were developed by continuing to select the males for increased 4-wk BW while selecting the females for increased (HW-HP line) or decreased (HW-LP line) TPP. The purpose of the present study was to determine the inheritance of traits assoc iated with growth and reproduction in reciprocal crosses between the d ivergently selected lines and sublines. Reciprocal crosses were made b etween the HW and LW, HP and LP, and HW-HP and HW-LP lines. Traits mea sured included BW at various ages, age at sexual maturity, egg product ion, ovarian follicular development, egg weight, TPP, wet and dry live r weights, and occurrence of smooth muscle tumors in the ligaments of the oviduct. The HW line differed from the LW line in all traits measu red except TPP and weight of smooth muscle tumors. No offspring were o btained from the HW x LW matings (male Listed first). In the LW x HW c ross, heterosis was negative for BW through sexual maturity and age at sexual maturity. Positive heterosis was observed for egg production, egg weight, and occurrence of smooth muscle tumors. Differences betwee n the HP and LP lines were observed in the selected trait (TPP) and so me correlated traits (BW at some ages, age at sexual maturity in femal es, egg production, and number and total weight of ovarian follicles). Positive heterosis in the HP and LP crosses was observed for BW, egg production, egg weight, and number of ovarian follicles whereas negati ve heterosis was observed for TPP and age at sexual maturity in female s. The HW-HP and HW-LP lines differed in the selected traits and some correlated traits (egg weight and weights of the Liver and smooth musc le tumors). Positive heterosis in the crosses was observed for BW, egg production, and liver weights whereas negative heterosis was evident for age at sexual maturity and TPP.