The EU ban on sow stalls during pregnancy, introduced in 2013, represented a major welfare advance, but group housing welfare depends heavily on management quality and system design.
Group housing improves sow welfare by allowing movement, social interaction and natural behavioural expression. However, poorly managed group systems can expose sows to chronic aggression stress that reduces welfare below that of well-managed individual housing. System design, space allowance and stable group composition are critical welfare determinants.