Play behaviour in farm animals is a reliable indicator of positive emotional states and welfare quality.
Farm animal play provides strong evidence that animals experience positive emotional states that matter for welfare assessment. Animals that have the opportunity and motivation to play are demonstrating that their needs are being met and they have energy beyond survival. High-welfare systems that allow play expression produce animals with better health outcomes and lower stress. The absence of play in conditions of crowding, illness, or restriction is a welfare warning signal that should trigger management review.