Pig production has changed dramatically over the last several decades, and most piglets are now raised on industrialized commercial operations that confine thousands of animals on one site. In these facilities, piglets are born and reared under conditions that dramatically contrast with the natural environment they are biologically adapted to fit. In nature, a mother sow builds a nest of twigs and leaves for the birth of her litter, and, after several days, the piglets gradually begin to leave the nest, explore their environment by rooting and nibbling, and slowly integrate into a larger family group. Piglets on commercial production facilities, however, are confined to barren, metal farrowing crates. Shortly after birth, they are subjected to a number of painful mutilations, including teeth clipping, tail docking, and ear notching, and male piglets are also castrated. All of these operations are routinely performed without the benefit of any pain-relieving anesthetics or analgesics. Piglets are weaned at an unnaturally early age, at a time when they would normally nurse frequently and depend on the mother sow for protection. Lack of outlets for normal exploratory nibbling, chewing, rooting, and foraging behavior, combined with early weaning practices, may lead to the development of abnormal oral behavior, such as tail biting and belly nosing. Early mortality is commonly high. Each of these issues is a highly significant animal welfare problem in need of immediate redress.
The Humane Society of the United States, "The Welfare of Piglets in the Pig Industry" (2010). IMPACTS ON FARM ANIMALS. 27.