Transitioning pigs from individual to group housing requires careful management to prevent aggression and ensure welfare benefits are realized in practice.
Group housing for sows represents a genuine welfare improvement over gestation crate confinement, but the welfare benefits depend heavily on how group housing is implemented and managed. The most significant risk is aggression during group formation and regrouping events. Pigs establish dominance hierarchies through fighting, and when unfamiliar animals are mixed, prolonged aggressive encounters cause injuries including skin lesions, lameness from fighting, and psychological stress in subordinate animals. Well-designed group housing systems that maintain stable groups, provide adequate space and resources, and use electronic feeding to reduce food competition realize the welfare advantages. Poorly managed systems may produce welfare outcomes comparable to or worse than well-managed individual housing.