Group Housing for Sows: Welfare Deep Dive
Legislative Background
EU Directive 2001/88/EC (and subsequent UK legislation) prohibited individual sow stalls except during the first 4 weeks of pregnancy. Sows must be kept in groups from 4 weeks post-service until 1 week before farrowing. This legislation was driven by welfare concerns about the severe movement restriction in individual stalls, which prevented normal behaviour including social interaction, exploration, and postural changes.
Welfare Benefits of Group Housing
Group housing allows sows to perform motivated behaviours: walking, social contact, investigatory behaviour, and postural changes. Welfare benefits include improved cardiovascular fitness, stronger limbs and bones, and reduced stereotypies compared to stall-housed sows. Social behaviour, including both affiliative and agonistic interactions, can be expressed.
Aggression and Welfare Challenges
The main welfare challenge in group housing is aggression, particularly at group formation and around feeding. Mixing unfamiliar sows triggers fighting to establish social hierarchy, causing injuries (skin lesions, vulval biting, lameness). Management strategies to reduce aggression include: stable group composition (avoiding repeated mixing); using ESF (electronic sow feeders) to reduce feed competition; providing adequate space (minimum 2.25m² per sow); and using visual barriers.
Feeding System Welfare
Feeding system design profoundly affects welfare. Electronic sow feeding (ESF) systems allow individual feeding and reduce competition. Floor feeding and trickle feeding reduce aggression around troughs. Shoulder stalls (short stalls open at the back allowing social contact) provide feeding protection. Water access must be adequate: a minimum of 10 litres per sow per day, with sufficient drinkers to prevent competition.
Monitoring and Improvement
Welfare assessment in group housing systems includes locomotion scoring, skin lesion scoring, body condition scoring, and assessment of stereotypic behaviour. Regular monitoring identifies problems early. Higher-welfare farms achieve low aggression scores through stable groups, good space allowances, and appropriate feeding systems. Continuous improvement based on welfare monitoring data drives progress beyond legislative minimum standards.