Abstract:
The purpose of this study was to demonstrate the effects of 11 generations of divergent selection on 5-week body weight in Japanese quail on both phenotypic and genetic variations of parameters of the Richards growth model. In total, 589 birds from a high body weight line (HL), a low body weight line (LL) and a random bred control line (C) were used in the study.
Following selection, body weight (BW) increased by 57.6% in line HL, while it decreased by 37.3% in line LL. The highest average BW (291 g) was found for females of line HL, whereas, the lowest mean BW (109 g) was identified in males of line LL (P<0.05). Significant differences were noted between lines in terms of parameters beta(0) and beta(1) of Richards function and coordinates of the point of inflection (IPA; age, and IPW; weight of point of inflection; P<0.05). In all three lines, the heritabilities for BW were found to be moderate to high. By the end of the selection, the genetic variation and heritability for BW decreased. While moderate heritabilities were found for IPA and IPW, estimates for other traits were low to moderate. Positive genetic and phenotypic correlations were found among BW-beta(0), BW-IPW and beta(0)-IPW. By the end of the study, it was revealed that 11 generations of divergent selection significantly affected both the phenotypic and the genetic variations of Richards growth model.