Swine breeds versus genetic lines

Pigs have been raised to produce food for over two thousand years. Today's domestic swine production systems are quite sophisticated, using multiple breeds in crossbreeding rotations to maximize overall production efficiency. Some breeds are used with a maternal emphasis in these production systems and include Landrace, Yorkshire, and Large White, among others. These breeds contribute greater lactation capability and litter sizes in a breeding program than other breeds. Other breeds are used with a paternal (often referred to as terminal) emphasis. Examples of terminal breeds include Berkshire, Duroc, Hampshire, Piétrain, or a combination of these and many other breeds. Terminal breed selection focuses on raising feed efficient, fast-growing pigs that produce meat products that people worldwide seek as part of their diet. Global pork production exceeds 100 million metric tonnes annually and is the most consumed meat animal protein in the world. Marketing weights (weight of the pig at end of the finishing period and just before slaughter) of pigs intended for food production range from less than 80 kg in some parts of the world to over 160 kg in others.