Many people interested in sustainably raised meat are concerned about the need to preserve heritage livestock breeds. Pigs are healthiest when they spend at least part of their lives on pasture, but the modern hog industry relies on only three or four breeds that have been developed for indoor operations. As a result, many of the qualities that help a pig survive outdoors — such as hair and dark-colored skin, which help protect pigs from sunburn — are disappearing from the gene pool.

On Flying Pigs Farm at Shushan, N.Y., Jennifer Small and Mike Yezzi have found that heritage breeds and sustainable farming are a winning combination. Their pigs are outside year-round grazing on pasture or foraging in the woods in the spring, summer and fall, and rooting in the snow in the winter. "I would say that heritage breeds are much hardier outdoors," Small says.

The main breeds raised on Flying Pigs Farm are Gloucestershire Old Spots, large, round pigs with white coats and black spots; Tamworths, tall, lean pigs that do well in a variety of climates and are known for their hardiness and distinctive dark red coloring; and Large Blacks, which are pigs with dark coats and rapid growth rates that do especially well on grass.

Small and Yezzi are members of American Livestock Breeds Conservancy, an organization that works with farmers across the country to preserve heritage livestock breeds. Other organizations working in this area include the New England Heritage Breeds Conservancy and Rare Breeds Canada.