Play in pigs is a reliable indicator of positive welfare states, and understanding and facilitating play has become an important dimension of high-welfare pig farming.
Pig play is a welfare indicator with a clear message: pigs that play have welfare resources to spare; pigs that do not are in states of deprivation or stress that preclude positive experience. This makes play frequency a sensitive early warning system for welfare problems -- a group that suddenly stops playing may be experiencing an environmental or social stressor before other welfare indicators deteriorate. Enriched housing systems that provide rooting substrate, social stability, and appropriate stocking density create the conditions in which play occurs naturally and frequently. The presence of play is not just absence of suffering; it is positive welfare in action.