Pigs are highly social animals with complex group dynamics. Group housing systems that support positive social behaviour improve welfare significantly over individual housing.
Social housing is not automatically better than individual housing if group management is poor. Frequent mixing of unfamiliar pigs causes high-intensity aggression as dominance hierarchies are re-established. Best practice minimises mixing events, maintains stable groups from weaning, provides adequate space to avoid confrontations and uses visual barriers to allow escape from dominant animals. Pigs in well-managed stable groups show the full range of positive social behaviours including play, huddling and mutual grooming - indicators of good welfare that individual housing can never provide.