Systematic welfare auditing at pig slaughter facilities using outcome-based indicators has demonstrated that measurable welfare improvements are achievable and that the range of welfare outcomes between facilities is very wide.
Pig slaughter welfare is shaped by the cumulative stress of lairage, the aversiveness of CO2 stunning, and the quality of stunning and sticking procedures. CO2 stunning is by far the dominant method in commercial pig slaughter and its aversiveness — confirmed by decades of behavioural and physiological research — represents a fundamental welfare problem embedded in the slaughter infrastructure of most major pig-producing countries. The excitation phase causes genuine suffering; pigs show distress vocalisation, attempts to escape, and physiological panic responses during the 15-30 seconds before loss of consciousness. Welfare audit systems that measure lairage vocalisation and stun effectiveness provide the data needed to identify underperforming facilities and drive improvement. The welfare of pigs at slaughter ultimately requires either improvement of CO2 stunning parameters or transition to less aversive alternatives — a major industry investment that requires commercial commitment and regulatory pressure.