Pig Social Behaviour and Group Management

Pigs are highly social animals with complex communication and group dynamics that are frequently disrupted by mixing practices in commercial production, causing aggression and welfare problems.

Key Facts

Pigs form stable social groups with recognized dominance hierarchies through which conflict is minimized once established.
Mixing unfamiliar pigs causes intense aggression as new hierarchies are negotiated — a major source of welfare-relevant injury.
Common mixing events include weaning, post-weaning mixing, moving to finishing pens, and transport loading.
Stable group management that avoids unnecessary mixing reduces aggression, injury, and corticosteroid levels significantly.
Larger groups of unfamiliar pigs show less intense individual aggression than smaller groups due to the cost of challenging all individuals.

Welfare Considerations

The mixing of unfamiliar pigs is one of the most significant predictable welfare events in commercial pig production. Pigs have sophisticated social cognition and rely on familiar individuals and established hierarchies for a stable social environment. Every time pigs are mixed, fighting occurs as new hierarchies are established — a predictable welfare cost that production management can reduce through stable group composition. Management systems that minimize mixing events provide measurably better welfare outcomes.

What You Can Do

Support certification schemes that require all-in-all-out group management reducing mixing events in pig production.
Choose pork products from farms with documented stable group management practices.
Advocate for farm assurance standards that limit unnecessary mixing events in pig production as a welfare criterion.
Support research into mixing management strategies and pheromone tools that reduce aggression during necessary regroupings.