Social Hierarchy in Pigs and Welfare Implications

Understanding pig social dynamics is essential for designing housing systems that minimise aggression and injury.

Key Facts

Pigs establish dominance hierarchies through fighting when unfamiliar pigs are mixed
Once established, stable hierarchies result in low levels of aggression
Mixing unfamiliar pigs causes fighting that may last 24-48 hours
Providing visual barriers and escape routes reduces injury severity when pigs are mixed
Space allowance at mixing significantly affects the severity and duration of fighting

Welfare Considerations

Pig social biology is well-understood and provides clear guidance for welfare-positive housing design. Stable social groups fight minimally. Mixing unfamiliar pigs creates fighting that causes injuries — ear tears, skin wounds, and occasionally severe injury. Well-designed mixing protocols with adequate space, visual barriers to retreat behind, and reduced resource competition can minimise the welfare cost of mixing. Avoiding mixing wherever possible through consistent group management is the highest welfare approach.

What You Can Do

Support welfare standards requiring group stability and mixing protocols in pig production
Choose pork from producers with documented group management practices
Learn about pig social behaviour and its housing design implications
Advocate for minimum space requirements that reduce aggression during mixing
Understand that cheap pork often reflects housing systems that accept high aggression rates