Heterosis for egg characteristics in reciprocal crosses of highly inbred lines of Japanese quail.

Abstract

Heterosis for egg characteristics was investigated in reciprocal crosses between highly inbred lines of Japanese quail. Two inbred lines (OO and TT), crossbreds from their reciprocal crosses (OT and TO) and a randombred population were used for this study. The two inbred lines were established by full-sib mating through 12 generations (F=92.5%). Measurement of egg characteristics was performed for egg weight, yolk weight, albumen weight, shell weight, egg width, egg length, egg shape index, albumen height, specific gravity, shell thickness, shell strength and yolk color.The crossbreds were superior to the parental inbred lines in egg weight, albumen weight, shell weight, egg length, specific gravity, shell thickness, shell strength and yolk color. In particular, there were significant differences between the crossbreds and the parental inbred lines in shell weight, specific gravity, shell thickness, shell strength and yolk color. Conversely, values for yolk weight of OT and egg shape index of both crossbreds were significantly lower than those of the inbred lines. In calculations of potence ratio, values higher than 1.0 were found for egg weight, shell weight, egg length, specific gravity, shell thickness, shell strength and yolk color, whereas negative values were found for yolk weight in OT and for egg shape index in both crossbreds as expected from the above observations. No reciprocal differences were detected between two kinds of crossbreds for egg characteristics other than egg shape index and albumen height.It is concluded that strong heterosis effects can be expected in egg qualities such as shell weight, specific gravity, shell thickness, shell strength and yolk color in the crossbreds of highly inbred lines of Japanese quail.