Pre-slaughter stunning of pigs is mandatory in most countries but methods differ significantly in their welfare profiles. CO2 stunning remains widespread despite evidence of aversiveness.
Pre-slaughter stunning welfare is one of the most significant welfare issues in pig production given the billions of pigs processed annually. The aversiveness of CO2 stunning is well-documented: pigs show hyperventilation, vocalisation, and escape attempts before unconsciousness. Despite this evidence, CO2 stunning dominates industrial processing due to automation advantages. Research into alternatives including nitrogen and argon gas mixtures, which cause less aversion, is ongoing. Electrical stunning methods when properly applied achieve rapid unconsciousness. Consumer and regulatory pressure is needed for less aversive methods.