Selection for Four-Week Body Weight in Japanese Quail Under Two Nutritional Environments

Abstract

THEORETICALLY the response to artificial selection proceeds at a decreasing rate until the limits to selection are reached. While Roberts (1966) discussed the limits to artificial selection for body weight in the mouse, comparable information for other species is unavailable. Realized heritabilities of 0.30 (Siegel, 1962) and 0.40 (Jaap, 1963) have been reported for short-term responses (four to five generations) to selection for 8-week body weight in chickens. Maloney et al. (1963, 1967) obtained realized estimates for 12-week body weight of 0.34 and 0.42 through 10 and 15 generations of selection, respectively. Eleven generations of selection for 8-week body weight yielded realized heritability estimates of 0.29 and 0.21 for two populations derived from crosses among commercial broiler stocks (Dev et al., 1969). While these estimates are in accord with a summary by Siegel (1962) of 176 published heritability estimates of body weights for chickens 6 to 12 weeks of age,…