Carbon dioxide stunning is the most commonly used method for pig slaughter but causes significant distress during induction, raising ongoing welfare concerns.
CO2 stunning is widely used because it is operationally convenient and allows high-throughput slaughter without individual animal handling. However, pigs experience significant distress during the 20-30 seconds before losing consciousness. High oxygen concentration CO2 and alternative noble gas mixes reduce aversion. Welfare advocates argue that operational convenience should not override the welfare cost of distressing induction, and that industry should transition to lower-aversion methods.