Heritabilities for duration of fertility traits in brown Tsaiya female ducks (Anas platyrhynchos) by artificial insemination with pooled muscovy (Cairina moschata) semen.

1. Fertility traits in 348 Brown Tsaiya female ducks were analysed following intergeneric crossbreeding by artificial insemination (AI) with pooled Muscovy semen. The females descended from 18 sires and 107 dams. At 50 weeks of age, the ducks were intra-vaginally inseminated once with 0.03 ml of pooled Muscovy semen. Subsequently eggs were collected for 15 d and set for incubation up to candling 10 d later. 2. Average fertility decreased from 87% at day 2 after AI to 53% at day 6 and less than 7% from day 10 onwards. 3. The best criterion of selection for duration of fertility seems to be the number of fertile eggs from 2nd day up to the 15th day after AI. Heritability estimates for this trait were hs2 = 0.29 +/- 0.18., hD2 = 0.38 +/- 0.22.