Play behaviour in pigs is a reliable indicator of positive welfare and an important welfare goal in itself; creating conditions for pig play improves welfare beyond mere absence of suffering.
Pig play is not merely a bonus feature of good welfare — it is an indicator that conditions are meeting the full spectrum of pig needs including positive emotional states. A welfare regime that prevents suffering but does not generate conditions for play has achieved the minimum but not the goal. Young pigs in deep straw systems with adequate space show frequent spontaneous play that is quantitatively associated with lower stress indicators and higher positive cognitive bias. The observation of play in a farm environment provides immediate, direct evidence of positive welfare that is more compelling to many people than biochemical stress measures. Promoting conditions for pig play is therefore both a welfare goal and a communication tool.