Pig Aggression Management When Mixing Groups

Managing pig aggression during group mixing requires strategies that minimize injury and stress while maintaining practical farm operations.

Key Facts

Pigs establish dominance hierarchies through fighting when introduced to new group members
Post-mixing aggression peaks in the first 24-48 hours and typically stabilizes within 72 hours
Injuries including ear biting, flank lesions, and vulva biting are common welfare outcomes of mixing
Mixing at night, in neutral pens, and with environmental enrichment reduces aggression intensity
Familiarity from nose-to-nose contact through barriers before full mixing reduces conflict
Larger groups may paradoxically show less serious fighting as stable sub-groups form

Welfare Considerations

Mixing is an unavoidable welfare challenge in commercial pig farming - production systems require regrouping at weaning, stocking, and resale. The welfare cost is real: injuries from mixing cause pain, impair normal behavior, and reduce feed intake. Welfare-focused management does not eliminate mixing but applies evidence-based strategies to reduce harm. Industry investment in mixing management training reflects growing recognition of this welfare priority.

What You Can Do

Apply petroleum jelly to backs and necks of newly mixed pigs to reduce grip and injury
Provide multiple enrichment points at mixing to redirect aggression toward objects
Mix pigs in neutral pens rather than established territory of any single group
Consider spraying all pigs with the same scent to reduce olfactory triggers of aggression
Monitor closely for 24-72 hours after mixing and remove severely injured individuals
Advocate for continued research into pheromone-based aggression reduction products