Play behavior in pigs is a reliable indicator of positive welfare states, with the presence and frequency of play reflecting environmental quality and the opportunity for positive emotional experiences.
Play is uniquely valuable as a welfare indicator because it signals genuine positive emotional states rather than merely the absence of negative ones. A pig that is playing is experiencing something positive - excess energy, safety, social trust, and environmental engagement. The presence of play therefore demonstrates that welfare conditions are good enough to produce positive experience. Measuring play behavior provides a welfare assessment that goes beyond identifying problems to confirming welfare is genuinely good. Farm systems that produce play behavior in their pigs are meeting not just minimum welfare standards but actively facilitating positive experiences.