Space allowance is a fundamental determinant of pig welfare, influencing aggression, injury, stress, and the ability to express natural behaviours. Current legal minimums fall significantly short of welfare science recommendations.
Space restriction in pig housing is a direct cause of welfare compromise, not merely a theoretical concern. Pigs at legal minimum stocking densities cannot lie in natural postures simultaneously, cannot avoid dominant pen-mates, and cannot engage in foraging or exploratory behaviour without competing for limited floor area. Social stress from overcrowding elevates cortisol chronically, suppresses immune function, and increases susceptibility to disease. Tail biting — one of the most serious welfare problems in commercial pig farming — is strongly associated with inadequate space. The welfare science is clear: minimum space allowances in most jurisdictions were set based on economic considerations rather than welfare evidence, and they need to be substantially revised.