Short-term selection for four-week body weight in Japanese quail.

Japanese quail have been utilized as a research animal to establish genetic relationships that may be present in other poultry species. In this presentation, short-term selection experiments were reviewed. Selection intensity appeared to be the most effective in improving BW when selection experiments were compared on a response per generation basis; however, when generation interval was reduced, the response per year was superior despite lower selection intensities for lines selected the same number of generations. Correlated responses over 30 generations of divergent selection for 4-wk BW indicated that selection had a negative effect on fitness traits, including egg number and fertility. Traits such as follicle and egg weight and BW at the beginning of and after a 120-d laying period were positively correlated with BW during the growth period. The early response of quail lines selected for increased BW at 10, 17, 28, and 40 d of age indicate that the later selection is applied the greater the selection response at maturity. In fact, lines selected at young ages were competitive with late-selected lines only to the point at which selection occurred.