Stocking density is one of the most significant drivers of pig welfare in commercial production. High densities restrict movement, increase aggression, and reduce access to resources, with measurable effects on health and behaviour.
Stocking density affects pig welfare through multiple interacting pathways. At high densities, subordinate pigs cannot avoid dominant individuals, rest in preferred locations, or access feed and water without competition. This chronic social stress manifests as elevated stress hormones, compromised immunity, and behavioural suppression. The relationship between density and tail biting is well-established: dense pens create frustration and redirected aggression that targets tail tips. Once a tail bite wound is open, pen-mates are attracted by blood, escalating to severe injury. The industry standard of treating tail biting through routine tail docking treats the symptom while leaving the underlying cause — insufficient space and enrichment — in place.