The EU ban on individual sow stalls (implemented from 2013, except during the first 4 weeks after service and around farrowing) has made group sow housing the norm across Europe. Managing groups of gestating sows well requires attention to social dynamics, feeding, individual monitoring, and space allocation to achieve good welfare outcomes.
Social Dynamics in Sow Groups
Pigs establish dominance hierarchies through fighting. When new sows are mixed — a necessary but disruptive event — aggression peaks in the first 24-72 hours. Careful mixing strategies reduce the severity and duration of fighting:
Mix at weaning rather than after service (reduces embryo loss risk)
Use a neutral pen that no sow considers her territory
Provide sufficient escape routes and visual barriers to reduce sustained pursuit
Mix similar-sized sows where possible
Provide deep straw bedding to reduce injury during mixing fights
Feeding Systems
Feed competition is the primary source of social stress and welfare variation between sows in group housing. Options include:
Electronic sow feeders (ESF): Individual computer-controlled feeding allows precise ration allocation to each sow. Gold standard for individual welfare monitoring but requires significant capital investment and management skill.
Floor feeding: Low cost but all sows must be fed simultaneously in sufficient space (at least 2m between individual feeding areas) to prevent displacement of subordinate animals.
EU Directive 2008/120/EC requires minimum 2.25m² per sow in dynamic groups. Research indicates that higher space allowances significantly reduce aggression, lameness, and stereotypy. The minimum is a regulatory floor, not a welfare optimum. Providing additional space and environmental complexity (straw bedding, rooting areas, objects) improves outcomes substantially.
Individual Monitoring
Group housing creates challenges for identifying individual animals that are failing to thrive. Regular observation with particular attention to:
Sows that are consistently displaced from feed
Abnormal body condition score change between service and farrowing
Lameness and injury monitoring
Stereotypy (bar-biting, repetitive movements) as indicators of chronic stress