What research reveals about optimal pig stocking density for welfare and production.
Pig stocking density is one of the most extensively researched welfare variables in farm animal science, and the evidence consistently shows that animals perform better — both in welfare terms and production terms — at densities below regulatory minimums. The legal minimum represents a political compromise rather than a welfare optimum, and welfare certification schemes have recognized this by requiring significantly more space. At high stocking densities, pigs cannot all lie simultaneously in optimal resting postures, cannot readily escape from aggressive pen mates, and face thermoregulation challenges in warm weather. The welfare and productivity evidence is aligned on this issue, creating an economic case for space investment that complements the welfare case.