Effect of reciprocal cross on growth related traits and carcass characteristics in an F2 intercross between two strains of Japanese quail

The objective of this study was to evaluate the effects of reciprocal crosses in the F2 generation of an intercross between two strains of Japanese quails. White (S) and wild (W) Japanese quail strains were crossed reciprocally and 31 F1 birds were generated. The white male × wild female and wild male × white female reciprocal crosses produced 17 SW and 14 WS progenies in F1 generation, respectively. The SW males were intercrossed to WS females, and WS males were intercrossed to SW females producing 157 SWWS and WSSW F2 offspring, respectively, in five consecutive hatches. Body weights of the SWWS and WSSW F2 birds at hatch and weekly weights until five weeks of age and carcass traits were recorded. The statistical model included the fixed effects of sex, hatch, reciprocal cross and random effects of sire, dam within sire and the residuals. The SWWS F2 progeny were heavier at 35 days of age (14.2 g) and produced heavier carcass (10.4 g) than the WSSW birds (P<0.01). The proportion of the F2 phenotypic variance explained by the reciprocal cross for live weights ranged between 3.0 to 19.0% (for W1 and W0, respectively) while the proportion of the variance due to the effect of reciprocal cross for carcass traits ranged from 0.9 to 16.1% for carcass fatness and cold carcass weight, respectively. The magnitude of the reciprocal cross substitution effects was similar in both males and females (P>0.05). The results suggested that the reciprocal cross effects observed in the F2 population derived from crossing of the two Japanese quail strains is likely due to the maternal effects or differences in the mitochondrial DNA.