Pigs establish complex social hierarchies through fighting when mixed in groups. Understanding social dynamics is essential for designing group housing systems that protect welfare.
Pig group housing welfare requires managing social dynamics that are inherent to a highly social species. The mixing of unfamiliar pigs is one of the most significant acute welfare events in pig farming, causing intense fighting and injuries. Systems that minimize mixing — maintaining stable groups from weaning to slaughter — dramatically reduce cumulative injury and stress. When mixing is unavoidable, providing adequate space for subordinate individuals to avoid dominant pigs, enrichment that redirects motivation away from conspecifics, and careful monitoring for severe fighting reduces harm. The alternative — individual sow stalls and farrowing crates — avoids mixing aggression by preventing all social behavior, representing a different but equally significant welfare compromise.