Maintaining stable social groups in pig farming rather than repeatedly mixing unfamiliar pigs dramatically reduces aggression, injuries, and stress that compromise welfare.
Stable social group management addresses one of the most consistent and preventable sources of welfare harm in commercial pig production. The aggression cascade that follows mixing of unfamiliar pigs involves genuinely severe welfare harm: severe bite wounds requiring veterinary treatment, sustained fighting that physically exhausts animals, and elevated stress hormones persisting well beyond the initial mixing period. The production system design choice to maintain stable birth groups throughout the production cycle eliminates this repeated welfare insult at relatively low cost. Producers who have implemented stable group systems consistently report reduced medication costs and mortality alongside welfare improvements, demonstrating the economic as well as ethical case for minimizing pig mixing.