Crossbreeding effects on reproductive traits in two strains of duck (Anas platyrhynchos): brown Tsaiya and Pekin.

1. The reproductive performances of 211 domestic duck females (Anas platyrhynchos) from the pure breeds Brown Tsaiya (Ts) and Pekin (Pk) and their two reciprocal crossbreds were analysed. 2. Differences in the 4 genotypes, additive direct and maternal crossbreeding effects and heterosis were estimated on the following traits: age at first egg, egg production to the ages of 30, 35, 40 and 52 weeks of age, egg weight at 30 weeks of age, and (egg) fertility by artificial insemination with Muscovy drakes' pooled semen. 3. Egg production up to 52 weeks of age was higher in Ts than in Pk (respectively 214 +/- 7 and 150 +/- 8 eggs), but not statistically different from that of the reciprocal crossbreds. The ratio of settable eggs to total eggs was nearly 90%, without any difference between genotypes. 4. Average egg weight at the age of 30 weeks was 75 +/- 0.9 g for Pk, which was higher than the corresponding values for Ts (62 +/- 0.8 g), but not significantly different from the crossbreds. 5. An effect of genotype was found on egg fertility: the Pk strain exhibited the lowest value, 71.3 +/- 3.1% compared with 75.9 +/- 2.1% for Ts, 80.6 +/- 2.6% for Ts x Pk and 74.6 +/- 1.9% for Pk x Ts. 6. Crossbreeding genetic variables showed favourable direct genetic effects for egg production and (egg) fertility in Ts, while Pk had favourable direct genetic effects on egg weight. The Pk genotype had a favourable maternal effect on fertility. Direct heterosis was 34% and 10% for egg production up to 30 and 52 weeks of age respectively, 8.8% for egg weight and 5.4% for (egg) fertility. 7. Crossing Ts with Pk seems profitable for the production of mule ducklings.