Estimation of Additive and Dominance Genetic Variances in Selected Layer Lines

Abstract

Both additive and dominance genetic variances for body weight at 256 days (BW), age at first egg (SM), egg weight at 252 days of age (EW) and egg production efficiency between 169-280 days (EP) were estimated in one Rhode Island Red line (Y8), three White Leghorn lines (E1, E4 and S46) and one Recessive White Rock line (L17) which were selected at the National Livestock Improvement Center, Okazaki Station. The proportion range of the dominance variance to total genetic variance for EW, BW, SM and EP were 0.11 to 0.18, 0.03 to 0.42, 0.06 to 0.41, and 0.08 to 0.35, respectively, and large differences among lines were found. These proportion suggested that the dominance might affect the expression of EW except for E4 line, and for BW in almost all lines. In addition, as for the four traits in L17 line, the effects of dominance were found because heterosis due to dominance might take an important role in this line. It is necessary to consider the dominance effects in genetic evaluation for selected lines, especially for lines which originated from cross breeding.