The transition from gestation crates to group sow housing is one of the most significant ongoing changes in pig farming welfare. Understanding what makes group housing succeed or fail is essential for maintaining welfare gains through industry transition.
Group sow housing welfare depends on implementation quality — poorly managed group housing can be worse than well-managed gestation crates, and the transition period requires careful management. Mixing unfamiliar sows causes intense aggression and injury — welfare-conscious systems minimise remixing events and use stable groups throughout gestation. ESF systems reduce feeding competition but sows still need space to move away from aggressive individuals. Space allocation is critical: minimum EU standards (2.25 m² per sow) may be insufficient in competitive groups — higher space allowances reduce aggression. Free access stalls that allow sows to voluntarily enter individual lying spaces provide the best balance of individual security and group interaction. Outdoor and deep-litter systems where sows can express rooting behaviour typically achieve the best welfare outcomes. Consumer-facing welfare certification should specify group housing management standards, not just the presence of group housing.