Inheritance of reproductive traits of female common ducks (Anas platyrhynchos) in pure breeding and in inter-generic crossbreeding with muscovy ducks (Cairina moschata).

1. Genetic parameters of reproductive traits were estimated in a population of common duck, in purebreeding and crossbreeding (with Muscovies) insemination systems. A total of 989 females were studied over three generations as well as 4025 purebred offspring and 4,125 male mule offspring. 2. Traits studied were age at first egg, total number of eggs laid until the age of 48 weeks, fertility and hatchability rates in pure and crossbreds, weight at 6 and 30 weeks of age, average egg weight and body weight of the male mule ducks at 6 weeks of age. 3. Heritability estimates were found to be medium range for reproductive traits (0.15 to 0.47). Heritability value for fertility or hatchability in crossbreds was twice as high as in purebreds (0.32 vs 0.15 for fertility; 0.36 vs 0.16 for hatchability). 4. Fertility in purebreeding and in crossbreeding were two different traits (r(g) = 0.49) while hatchability displayed a high genetic correlation between breeding systems (r(g) = 0.88). 5. Genetic correlations with number of hatched mule ducks were medium or high and favourable. Genetic correlations between reproductive traits and weights were low (< 0.36), the most related trait being the body weight of the male mule duck at 6 weeks of age.