Pigs and Social Hierarchy Formation Welfare

The mixing of unfamiliar pigs in commercial systems triggers aggressive hierarchy formation with significant welfare costs.

Key Facts

Pigs establish dominance hierarchies through aggressive encounters that can last 24 to 48 hours when unfamiliar groups are mixed
Mixing occurs regularly in commercial systems at weaning, grower, and finisher stages
Fights during mixing cause skin wounds, stress, and reduced feeding in all pigs for days after introduction
Agonistic behavior decreases significantly once hierarchy is established within stable groups
Keeping stable social groups from birth to slaughter eliminates mixing stress and reduces medication use

Welfare Considerations

Commercial pig systems that routinely mix unfamiliar pigs create predictable, preventable welfare harm. The fighting that occurs is not mild — it involves sustained attacks, skin damage, and physiological stress that persist for days. Stable group management from birth to slaughter is achievable and simultaneously reduces welfare harm, injury, and antibiotic use.

What You Can Do

Support certification schemes requiring stable social groups from weaning to slaughter without mixing
Advocate for research demonstrating the production benefits of stable social group management to drive industry adoption
Choose pork from systems certified for stable group housing throughout the production cycle