Pig Pre-Slaughter CO2 Stunning: Welfare Debate

High-concentration CO2 stunning is widely used in pig slaughter but causes aversive responses before unconsciousness, sparking ongoing welfare debate about its acceptability.

Key Facts

Approximately 70% of pigs in the UK and EU are stunned using high-concentration CO2 (80-90%) before slaughter
CO2 is aversive to pigs before unconsciousness occurs, causing a period of distress including escape attempts and gasping
The time to unconsciousness in high CO2 is approximately 30-40 seconds, during which pigs experience acute distress
Alternative systems using lower CO2 concentrations, argon mixtures or two-phase systems aim to reduce aversion
EFSA has evaluated CO2 stunning and confirmed it causes significant aversion and potential suffering before unconsciousness

Welfare Considerations

The widespread use of high-concentration CO2 stunning represents a significant unresolved welfare problem in commercial pig slaughter. The scientific evidence is clear that pigs find CO2 acutely aversive and experience distress before losing consciousness. Industry adoption of CO2 was driven by throughput efficiency advantages rather than welfare considerations. The development and adoption of less aversive gas combinations or alternative stunning methods is a welfare priority that requires regulatory pressure and investment.

What You Can Do

Advocate for regulatory review and timetable for phasing out high-concentration CO2 stunning
Support research into less aversive gas combinations and alternative stunning methods for pigs
Choose pork from producers that use alternative stunning systems where available
Engage with pig sector organisations about the timeline for transitioning to more humane stunning
Support organisations like Humane Slaughter Association working on more humane slaughter methods