Muscovy duck
The Muscovy duck can be crossed with domestic ducks in captivity to produce hybrids, known as mulards ("mule duck") because they are sterile. Muscovy drakes are commercially crossed with domestic duck birds, either naturally or by artificial insemination. The 40–60% of eggs that are fertile result in birds raised only for their meat or for production of foie gras: they grow fast like domestic ducks, but to a large size like Muscovy ducks. The inverse cross, domestic drake with Muscovy duck, is possible, but infrequent.