Managing Aggression in Group-Housed Pigs: Practical Solutions

Aggression in group-housed pigs causes injury and stress, and management of mixing, resources, and space significantly reduces aggressive interaction rates.

Key Facts

Pen-level aggression peaks at mixing events and during competitive resource access
Electronic sow feeders (ESF) eliminate competitive feeding aggression in group-housed gestating sows
Multiple feed points (minimum one per 5 pigs) reduce competitive exclusion from feeders
Providing visual barriers within pens allows subordinate pigs to escape dominant animals
Refuge areas or escape corners reduce injury in aggressive encounters
Breed differences affect aggression levels - some breeds are more reactive than others
Anti-androgen treatment has been evaluated for reducing aggression in uncastrated boar pigs

Welfare Considerations

Aggression in group-housed pigs causes injury, chronic stress for subordinate animals, and reduced feeding opportunities that compound into body condition loss. Management of pen design, resource provision, and mixing protocols can substantially reduce aggressive interaction frequency and severity. The welfare imperative is not to eliminate all aggression - some social interaction is natural and normal - but to prevent aggressive interactions from causing injury and chronic stress. Evidence-based approaches to feeding system design, space provision, and mixing management achieve this.

What You Can Do

Provide multiple feeding points to prevent competitive exclusion from feeders
Use physical barriers within pens to allow escape and reduce injury from aggressive encounters
Implement pre-mixing contact (fence-line or partition) before full group mixing
Provide rooting substrate that reduces redirected aggression toward pen mates
Monitor injury prevalence as an aggression welfare indicator - any pen with >30% skin lesions requires investigation
Separate and treat severely injured pigs promptly to prevent wound progression
Review stocking density if aggression rates are high - providing more space reduces intensity