It is created from a cross between a male Muscovy (aka Barbary) duck, and a female from another duck breed. Because the Muscovy duck is actually a different species,”Cairina moschatvs Anas platyrynchos”, from all other ducks, the offspring is sterile and can’t breed other offspring. The birds won’t be fliers, either.
The rate of offspring actually produced between Muscovy and other ducks is actually quite low only, 20-30%, so it’s boosted up to 80% by using artificial insemination. Incubation of the eggs takes an average of 32 days.
Mule Ducks are bred for several reasons. One is that they will have lean, large breasts, about 8 to 10 oz (225 to 280g) per breast.
France: Moulard Ducks
In France, the word used is “Moulard”, and usually implies the cross was between a male Muscovy duck, and a female Pekin duck. Occasionally, the female may be a Rouen.
In France, Moulard ducks are bred specially for foie gras production and for meat. The resultant females are valued for their large breasts; the males are valued for foie gras production, because the males are larger and hardier, making them better able to stand up to the forced feeding (“gavage”), and the female livers are often veined, causing them to get downgraded.
In the 1960s, foie gras production switched from geese to Moulard ducks, as they are less expensive to keep than geese. In searching for an alternative to geese, straight-up Muscovy ducks were first tried, but they react against the forced feeding, so the idea of Muscovy cross-breeds was hit upon.
Taiwan: Mule Ducks
In Taiwan, it’s common to cross white male Muscovy duck with a breed of white duck known as a Kaiya (developed itself from a cross between Pekin and Tsaiya duck) to get very finely textured and lean meat which has about 18% fat content (compared to 30% in a Pekin.) The female ducks grow as fast as the males, and both have good breast meat.
The birds are quiet, and much calmer than Pekin ducks. They will swim, but not fly.
The resultant ducks also have white feathers, which are valued in themselves as a commodity. There’s another bonus, though: as the feathers are white, when the carcasses are plucked there’s no sign of black or pigmentation where the pin feathers were — Chinese consumers prefer a cleanly plucked duck carcass with no black marks.
The female ducks are also very good egg layers.
The practice of breeding mule ducks has been done in Taiwan for more than 275 years. To increase the success rate, the mating for the mule used to be done by hand, with farmers holding the two ducks together.
A Mule Duck is called a “hinny” duck, if the breeding is done the other way: female muscovy with a male common duck.
In French, a “mulet” is a male sterile hybrid; a “mule” is a female sterile hybrid. From the Latin “mulus”, meaning a sterile hybrid.
Hoffman, Ed, Dr. Mule Duck. Canning, Nova Scotia, Canada. December 1993. Retrieved March 2011 from http://www.feathersite.com/Poultry/Ducks/Musc/Mule.html