Mixing unfamiliar pigs triggers intense aggression and welfare harm, yet commercial pig production routinely disrupts social groups through weaning, moving and regrouping at multiple lifecycle stages.
Social mixing welfare in pigs illustrates the gap between what would be welfare-optimal — stable social groups throughout the lifecycle — and what commercial pig production typically provides. From weaning disruptions to repeated regrouping as pigs move between production stages, commercial pigs experience multiple cycles of social disruption, each triggering aggression, injury and welfare stress. The evidence for better approaches — gradual introductions, stable groups, appropriate management during mixing events — is available. Implementation requires investment in staff training and facility design that many commercial operations have not prioritized. Welfare certification that rewards stable social group management would create market incentives for this important improvement.