Regrouping events throughout the pig production cycle cause aggression that injures animals and compromises welfare. Evidence-based management minimises suffering during these unavoidable events.
Regrouping aggression is predictable and manageable yet remains one of the most consistent acute welfare problems in commercial pig production. The evidence for prevention is clear: olfactory familiarisation through fenceline contact before mixing, nocturnal mixing with reduced lighting, immediate enrichment provision and adequate space all reduce the frequency and severity of aggression injuries. Despite this evidence, regrouping management quality varies enormously between farms. The welfare investment required is primarily in time and planning - the physical interventions are inexpensive. Farms that implement regrouping protocols consistently report reduced veterinary costs from wound treatment alongside better welfare outcomes.