Play is a reliable indicator of positive emotional states in pigs, and its presence or absence provides important information about farm welfare.
The presence of play in pigs is a powerful positive welfare indicator. When pigs play, they are communicating that basic needs are met and positive emotions are present. Barren environments that prevent play are welfare-impoverished regardless of other measures. Farm systems that make room for play - through space, enrichment, and appropriate social grouping - are producing evidence of genuine positive welfare rather than just absence of suffering.