Pigs are highly social animals for whom group housing is welfare-essential. Managing group dynamics to prevent bullying and injury while allowing positive social interaction is a management skill.
Group housing is welfare-essential for pigs because of their social nature, but it introduces management challenges that require skill to navigate. When unfamiliar pigs are mixed — a routine occurrence in commercial systems when groups are redistributed — they fight to establish dominance hierarchies, causing injuries and immune suppression that increase disease risk. Stable groups raised together from birth experience far less aggression because hierarchies are established early and maintained without repeated confrontation. Where regrouping is unavoidable, providing adequate space, enrichment that redirects aggression, and separation options for severely bullied individuals reduces welfare harm. The transition from gestation crate to group sow housing, now mandated for most of EU pregnancy, has improved welfare substantially while demonstrating that group management is commercially viable.