The method of stunning and killing pigs at slaughter has profound welfare implications. Effective stunning must render animals instantly insensible, and the choice of method affects the number of pigs that experience conscious killing procedures.
CO2 stunning causes genuine suffering during the induction phase - pigs clearly find the gas aversive. The industry's preference for CO2 is driven by throughput efficiency rather than animal welfare. Alternative stunning methods that avoid the aversive induction period exist and are technically feasible. Transitioning away from high-concentration CO2 stunning represents a practical welfare improvement that the pork industry has been slow to adopt.