Pig Social Hierarchy and Welfare

Understanding pig social hierarchy and the welfare costs of its disruption informs management strategies that minimise aggression and injury.

Key Facts

Pigs establish stable social hierarchies through aggression when unfamiliar animals are mixed
Established hierarchies involve minimal aggression as subordinate animals avoid dominant individuals
Hierarchy disruption from mixing causes sustained fighting for 24-48 hours with injury risk
High stocking density prevents subordinate pigs from moving away from dominant animals
Providing multiple feeding and water points reduces competition at resources causing aggression

Welfare Considerations

Social hierarchy stress is a major welfare cost in systems that frequently mix unfamiliar pigs. Each mixing event triggers hierarchy re-establishment with physical aggression that causes injury and stress. Management strategies that maintain stable groups from weaning through to slaughter dramatically reduce this welfare cost. Where mixing is unavoidable, providing escape routes, multiple resources, and enrichment reduces but cannot eliminate the welfare cost of hierarchy disruption.

What You Can Do

Support pig welfare certification preferring batch systems minimising regrouping
Advocate for minimum resource provision per pig as a welfare assurance standard
Choose pork from farms with documented group stability management programmes