The housing of pregnant sows is one of the most welfare-significant and contested issues in pig production. Individual gestation stalls restrict sow movement to the point where sows cannot turn around, while group housing allows social behavior but introduces competition and aggression risks. The welfare evidence strongly favors group housing with appropriate management.
The Welfare Case Against Individual Stalls
Gestation stalls confine sows in spaces approximately 60cm wide and 2m long for the majority of their 16-week pregnancy. In these stalls, sows cannot turn around, take more than one or two steps forward or back, or engage in any natural behavior beyond eating, drinking, and lying. Research consistently finds that stall-housed sows show higher rates of stereotypic behaviors (bar biting, rooting air), higher cortisol levels, greater fearfulness, poorer leg and hoof condition from standing on concrete with limited movement, and evidence of learned helplessness — a state associated with chronic inescapable stress.
The frustration of locomotion, exploration, social behavior, and foraging in stall-housed sows represents a profound and sustained welfare cost. The European Union banned individual gestation stalls for the majority of pregnancy in 2013, a decision grounded in the scientific evidence base for sow welfare.
Group Housing: Welfare Benefits and Challenges
Group housing allows sows to walk, turn, and engage in social behavior, meeting fundamental behavioral needs. Sows in well-managed group housing show lower cortisol levels, more positive behavioral indicators, and better leg health than stall-housed sows. These welfare benefits are robust across studies.
The primary welfare challenge in group housing is aggression, particularly when groups are mixed. Establishing dominance hierarchies involves fighting that can cause injury to ears, flanks, and vulvas. Management strategies to minimize aggression include mixing sows at weaning rather than after confirmation of pregnancy, providing adequate space (minimum 2.25 m² per sow for dynamic groups), multiple feeding stations or ESF to reduce feeding competition, and ensuring hiding and escape opportunities through pen design.
2025 Status and Trends
As of 2025, group housing is the legal standard across the EU and is increasingly required by retailer welfare standards globally. North America is transitioning more slowly, with growing retailer commitments driving adoption among major producers. The science unambiguously supports group housing as the welfare-superior option when managed appropriately, and implementation experience across a decade of EU compliance has built substantial knowledge of how to manage groups effectively.