The slaughter of pigs involves welfare challenges at every stage from arrival to killing. Stunning method choice, animal handling, and equipment maintenance all significantly affect welfare outcomes for hundreds of millions of pigs annually.
Pig slaughter welfare represents one of the most significant and technically tractable welfare problems in commercial agriculture. The scale is enormous — over a billion pigs slaughtered annually — and the welfare implications of different stunning methods are well-documented. CO2 stunning is currently the dominant method in high-throughput European slaughter plants because it allows continuous throughput without the need to physically handle individual pigs for restraint and electrical stunning. But CO2 at the concentrations used is aversive: pigs exposed to it show behavioral signs of distress — hyperventilation, escape attempts, vocalizations — for 20-30 seconds before losing consciousness. Research into alternatives including lower CO2 concentrations with inert gas mixtures, and low-atmospheric-pressure stunning, is motivated precisely by the welfare concern with current methods. Electrical stunning avoids the CO2 aversion problem but requires individual handling that creates different welfare challenges in high-throughput settings. The common thread across all methods is equipment maintenance, training, and monitoring: a poorly maintained or incorrectly operated system of any type causes preventable welfare harm.