CO2 Stunning for Poultry: Welfare Evidence

CO2 stunning for poultry is widely used but evidence of its welfare implications has prompted calls for improvement.

Key Facts

Over 50% of UK broiler chickens are stunned using high-concentration CO2 before slaughter
CO2 stunning at standard concentrations causes aversion behaviour before unconsciousness
Birds show increased wing flapping, head shaking, and escape attempts during CO2 exposure
Low-oxygen stunning (inert gas systems) produces less aversion and is considered a welfare improvement
Waterbath electrical stunning, the alternative, causes pain if incorrectly applied but less aversion

Welfare Considerations

CO2 stunning is used in poultry slaughter because it allows group processing without individual handling — a practical and commercial advantage. But the welfare evidence is concerning: birds are aware of and distressed by CO2 exposure before losing consciousness. The aversion response — birds actively trying to escape — indicates genuine distress. Inert gas alternatives (argon, nitrogen) produce unconsciousness through hypoxia without the aversive CO2 irritation. Transitioning to these alternatives requires capital investment but represents a welfare improvement accessible to the industry.

What You Can Do

Support campaigns for inert gas stunning adoption in major poultry processors
Advocate for investment in low-oxygen stunning infrastructure in poultry welfare standards
Choose poultry products from processors that have adopted inert gas stunning
Support research comparing welfare outcomes of different poultry stunning methods
Engage with the poultry industry on slaughter welfare improvement as an achievable priority