Gestation-Free Pig Systems: Welfare Analysis
Gestation stalls — individual sow stalls so narrow that sows cannot turn around — were banned in the EU from 2013 (except during the first 4 weeks post-service). This transition to group housing during gestation was driven primarily by welfare concerns about the severe behavioural restriction of stall systems. Understanding the welfare improvements and remaining challenges of group gestation is important for continued welfare progress.
Welfare Improvements in Group Gestation
Group housing enables sows to express natural behaviours — locomotion, social interaction, investigation, rooting, and postural variety. These behaviours are completely restricted in gestation stalls. Sows in groups can maintain natural social relationships, engage in social play (in enriched systems), and experience positive social interactions rather than isolation.
Bone strength and muscle mass are significantly better in group-housed sows than in stall-housed sows — reflecting the ability to move and exercise. Lameness rates, fracture risk, and leg problems are lower in group systems with appropriate flooring. Psychological welfare indicators (stereotypy frequency, cognitive bias, response to novel objects) consistently favour group over stall housing.
Welfare Challenges of Group Systems
Group housing creates welfare challenges that stall systems avoided — primarily social aggression when establishing or re-establishing hierarchy. Mixing unfamiliar sows creates fighting that can cause significant injury. Management strategies to minimise mixing stress include: maintaining stable groups throughout gestation; introducing new sows to established groups only once; providing adequate space and resources to reduce competition; and using appropriate feeding systems (ESF or floor feeding with adequate space).
Electronic Sow Feeding in Group Systems
Electronic sow feeders (ESF) allow individual feeding of sows within group housing. Each sow receives her individual ration delivered by RFID identification. This prevents dominant sows from consuming others' rations and allows precision body condition management. The welfare benefit of individual nutrition combined with group social housing represents the ideal of group gestation systems when ESF is well-managed.