Estimation of the genetic parameters of sexual dimorphism of body weight in 'label' chickens and Muscovy ducks

The genetic parameters of sexual dimorphism of body weight were estimated i n samples of 16190 chickens and 11328 Muscovy ducks. A multivariate animal model was used, and weights of males and females were treated as different traits. Heritabilities were estimated for males and females, respectively, at 0.28 +/- 0.04 and 0.43+/-0.04 for body weight at 8 weeks in chickens (BW 8), and in ducks at 0.40 +/- 0.04 and 0.51 +/- 0.04 for body weight at 6 we eks (BW6) and 0.33 +/- 0.05 and 0.67+/-0.05 for weight gain between 6 weeks and slaughter (WG). The estimated genetic correlations between sexes were 0.84 for BW8 in chickens, anti 0.85 and 0.73 for BW6 and WG in ducks, respe ctively. Maternal heritabilities were generally higher in males than in fem ales. Heritabilities of sexual dimorphism were estimated as 0.08 for BW8 in chickens, and at 0.13 and 0.18 for BW6 and WG in Muscovy ducks, respective ly. Sexual dimorphism in both species was highly and positively correlated with traits of males (between 0.65 and 0.84), and slightly and positively c orrelated with growth potential of females (between 0.13 and 0.25). (C) Inr a/Elsevier, Paris.