China is now the top market for US breeder hogs, whose genetic advantages improve productivity on Chinese farms.

Through November, China was the top destination for exports of live US hogs in 2012 in terms of value - US$16.28 million for 12,138 animals, said Joe Schuele, a spokesman for the US Meat Export Federation, an industry trade group.

For China, the US was the biggest supplier of live-hogs last year, with much smaller imports from Canada, France and Britain. For US hog breeders, other major export markets were Mexico, Canada and Russia.

China, where pork is a dietary staple, is importing US breeder hogs to help meet the protein demands of its growing middle-class population. US breeders are facing declining consumption and rising production costs at home.