The transition from individual to group housing for sows requires careful management to deliver welfare benefits and avoid aggression problems.
The transition to group housing for pregnant sows is welfare-positive when well managed and potentially welfare-neutral or negative when poorly managed. The key challenge is aggression during mixing, which causes injuries that undermine welfare benefits. Systems that maintain stable social groups, use electronic feeding to eliminate resource competition, and have handlers trained to recognize and respond to aggression early can achieve dramatically better welfare outcomes than those that mix sows routinely without management attention. The welfare benefit of group housing depends entirely on implementation quality.