Three breeds of pig are traditional in American pork production, with a fourth breed often serving for crossbreeding with the primary types. These breeds make up 87 percent of all domestic pig production, according to the National Swine Registry. Early domestic pigs were considered either bacon or lard types. Because lard demand declined so precipitously after World War II, the breeds in production today all descend from "bacon" ancestors.
The most common pig breed in North America, the white Yorkshire pig has upright ears. No black spotting is permitted in the breed. While the Yorkshire breed comes in three distinct sizes -- small, medium and large -- only the latter is traditionally found in the American pork industry. Yorkshires arrived in the United States about 1830. An extremely muscular type, the typical Yorkshire carcass contains a great deal of lean meat, with little fat on the back.
The Duroc is the second most common pig breed in the United States, according to the National Swine Registry. Duroc colors range from dark red to golden. The breed sports drooping ears. No white is permitted by the breed standard except for the end of the nose. Durocs are allowed a maximum of three black spots on the body, although none can exceed 2 inches in diameter. Often used in crossbreeding, the Duroc originated in the United States in the early 19th century.
Although it boasts an English name, the Hampshire is considered a traditional American breed, first imported to the United States in the 1820s. Known by many other names across the country, including the McKay and McGee, this black pig with white belting and erect ears was officially christened the Hampshire in the early 20th century. This large pig is exceptionally robust, with fine foraging abilities when kept on family farms. The white belt completely encircles the front of the trunk, including the front legs and feet.
A native Danish pig, the white, droopy-ear Landrace are exceptionally prolific, and they cross well with other breeds. Not only do Landrace sows give birth to large litters, those piglets tend to be bigger than other breeds. The Landraces' exceptionally long bodies provide additional pork loin and ham.
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