Pen design features including barriers, escape routes, and feeding space significantly affect aggression levels in pigs. Evidence-based design reduces welfare harm from fighting.
Aggression in pig groups causes real welfare harm — the wounds from biting are painful, infection risk is significant, and chronic subordination stress is a sustained negative welfare state. Pen design can dramatically affect aggression levels independently of management decisions. Providing visual barriers reduces the ability of dominant pigs to monitor and repeatedly attack subordinates; ensuring adequate feeding space reduces competitive feeding aggression; and multiple levels or complexity allow escape routes that reduce sustained attacks. These design interventions are cost-effective welfare improvements that benefit all pigs in a group.