Group housing is increasingly adopted for pigs across production phases. The science of pig social behaviour guides best practices for minimising aggression and promoting positive social welfare.
Pig social welfare science has produced actionable knowledge about how to manage group housing to minimise aggression-related harm. The critical welfare event in group housing is mixing — introducing unfamiliar pigs triggers intense fighting to establish dominance hierarchies. Strategies that reduce mixing aggression include scent camouflage (spraying all pigs with a uniform smell before mixing), providing extensive hiding/retreat options, and ensuring high stocking space in the first 48 hours to allow flight responses. Once stable groups are established, consistent composition should be maintained — each unnecessary mixing event restarts aggression cycles. Feed management dramatically affects social welfare: floor or scatter feeding reduces competitive pressure at single feeding points; providing at least one feeding space per animal or using electronic sow feeders prevents resource monopolisation. Large group dynamic research suggests that larger, stable groups in sufficient space may produce better overall welfare than small groups, as the dominance hierarchy becomes less individually impactful when group size allows subordinates more effectively to avoid dominants.