Pig Social Hierarchy and Group Housing Welfare

Pigs are highly social animals with complex dominance hierarchies. Understanding pig social behaviour is essential to reducing aggression and improving welfare in group housing systems.

Key Facts

Pigs establish stable dominance hierarchies within 24-48 hours of group formation
Mixing unfamiliar pigs causes intense fighting that can result in serious injury or death
Providing escape routes and visual barriers significantly reduces aggression in mixed groups
Boars reach sexual maturity at 4-5 months and add hormonal aggression to social mixing
Higher space allowances — above EU minimum of 0.65 m2 per pig — substantially reduce tail-biting

Welfare Considerations

Group housing is widely considered better than individual confinement for pig welfare, but poorly managed group systems can cause significant harm through social aggression. The key welfare interventions are: mixing pigs only at weaning or early ages when hierarchies establish with less injury, providing adequate space and environmental enrichment, and using nose-ringing alternatives or tail-docking reduction paired with better management. Stable, well-managed groups allow pigs to express natural social behaviour positively.

What You Can Do

Support standards that require enriched group housing with adequate space allowances
Choose pork certified by RSPCA Assured or equivalent schemes with social housing requirements
Advocate for mixing protocols that minimise fighting at restocking
Encourage research into pheromone-based aggression reduction tools for pig facilities