Managing Pig Aggression: Welfare Solutions for Mixing and Social Stress

Pig aggression during mixing causes serious injuries and significant welfare costs. Evidence-based management strategies dramatically reduce harm.

Key Facts

Pigs establish dominance hierarchies through fighting when mixed with unfamiliar conspecifics
Post-mixing aggression typically peaks in the first 24-48 hours and can cause severe injuries
Aggression during mixing is a leading cause of mortality and chronic pain in growing pigs
Providing hiding barriers in mixing pens allows subordinate animals to escape attack
Familiar odor exposure before mixing (pen swap) reduces aggression intensity significantly
Mixing at night, providing novel enrichment, and spraying all pigs with the same scent are proven mitigation strategies

Welfare Considerations

Pig mixing aggression causes thousands of serious injuries annually in commercial production. The pain of bite wounds, ear injuries, and flank lacerations from mixing fights is acute and significant. Proven, low-cost interventions including providing visual barriers, timing mixing at night, applying masking scents, and offering enrichment at the moment of mixing reduce injury rates substantially. Longer-term, keeping pigs in stable social groups from birth to slaughter without mixing events eliminates this welfare challenge entirely — an approach increasingly adopted by higher welfare producers.

What You Can Do

Support pork producers using stable social group management from birth to slaughter without mixing
Advocate for enrichment and hiding space requirements in pig housing regulations
Learn about the evidence-based interventions that reduce pig mixing aggression
Choose pork certified to welfare standards that address social stress and mixing management