Pig social behavior is complex and hierarchical, and understanding pig social dynamics enables management decisions that reduce aggression and improve welfare throughout the production cycle.
Pig social behavior welfare is primarily managed through minimizing mixing of unfamiliar animals and providing appropriate space for hierarchy expression. The mixing of pigs - which occurs at weaning, regrouping, and transport - triggers intense fighting as dominance hierarchies are (re)established. This fighting is a normal social process but causes welfare harm through injuries, stress, and energy expenditure, particularly in commercial settings where available space limits retreat options for subordinate animals. Stable groups with established hierarchies show very low aggression rates - the welfare problem is primarily in the disruption events. Management systems that maintain stable social groups from birth to slaughter dramatically reduce cumulative aggression. Pen design that provides visual barriers, multiple feeding and resting areas, and escape routes for subordinate animals reduces aggression severity during unavoidable mixing events.