Pig slaughter welfare depends on effective stunning before killing with CO2 stunning raising welfare concerns due to the aversive response of pigs to high CO2 concentrations during induction.
CO2 stunning of pigs represents one of the most significant welfare challenges in current commercial slaughter practice. During the approximately 30 seconds between exposure and insensibility, pigs experience acute respiratory distress that is highly aversive. The scale of pig slaughter means this welfare problem affects hundreds of millions of animals annually. Scientific consensus from EFSA confirms the aversion, yet CO2 remains dominant due to the capital investment required to change established infrastructure. Low-oxygen alternatives would eliminate the aversive induction period at the cost of transition investment. Consumer and regulatory pressure is gradually building for transition away from CO2 stunning.