Stocking density — the number of animals per unit of floor space — is one of the most important determinants of pig welfare. Evidence-based space requirements differ significantly from current industry standards.
Pig stocking density science provides some of the clearest evidence in farm animal welfare: less space means more welfare compromise, more consistently and measurably than almost any other variable. At current EU legal minimums, pigs cannot simultaneously stand, lie, and access feeders without being in contact with each other — a space constraint that produces chronic social tension, resource competition, and the frustration that drives tail biting. Preference tests and behavioral budgets both indicate that pigs require substantially more space than current regulations provide to express their full behavioral repertoire and maintain normal social relationships. The good news is that the evidence base for regulatory reform is strong, and the economic analysis of tail biting costs shows that increased space at appropriate enrichment can be economically viable.