Farmed Pig CO2 Stunning Welfare Debate

CO2 stunning of pigs before slaughter is widespread but causes a distressing aversive experience, and research into alternatives is ongoing.

Key Facts

CO2 stunning is used for approximately 70% of UK pigs slaughtered in large abattoirs
CO2 inhalation causes pain from the acidic mucous membrane reaction before unconsciousness
Pigs show clear aversion to CO2, attempting to escape the gas chamber
Argon gas mixtures cause less distress but are more expensive and less available
High CO2 concentration systems reduce time to unconsciousness but do not eliminate the aversive phase

Welfare Considerations

CO2 stunning represents a welfare compromise in pig slaughter: it is effective at producing unconsciousness but causes a period of significant distress - typically 30-40 seconds - during which pigs experience aversion, breathlessness, and distress before losing consciousness. The industry has adopted it for efficiency and practicality reasons despite this known welfare cost. Research into alternative gas mixtures and rapid induction systems aims to reduce this welfare burden.

What You Can Do

Support research into CO2 alternatives for pig stunning
Advocate for welfare-based stunning requirements in slaughter legislation
Choose pork from producers using highest welfare stunning available
Engage with retailers about their slaughter welfare requirements for pig suppliers
Support RSPCA and Humane Slaughter Association advocacy for stunning improvements