Pig CO2 Slaughter Welfare Science

Evaluating the welfare of carbon dioxide stunning systems in commercial pig slaughter.

Key Facts

CO2 stunning is used for approximately 90% of pigs slaughtered in the UK and Scandinavia
CO2 gas causes aversion and distress before unconsciousness - pigs struggle and vocalize during exposure
Alternatives including high inert gas concentrations (argon, nitrogen) cause unconsciousness without aversion
The five domains model classifies CO2 stunning as causing significant negative mental states
Animal welfare scientists broadly recommend transitioning away from CO2 stunning
Equipment modification costs are the primary barrier to transition to inert gas systems

Welfare Considerations

CO2 pig stunning represents one of the most welfare-controversial practices in commercial livestock slaughter, as scientific evidence consistently demonstrates that pigs experience significant distress during the exposure period before losing consciousness. The aversion response is not a reflexive convulsion but an experienced negative state. Despite this clear evidence, CO2 stunning remains dominant due to the capital cost of converting to inert gas alternatives and the efficiency advantages of pit-based systems. The welfare case for transition to less aversive stunning methods is clear, and the food industry's commitment to progress is the critical limiting factor.

What You Can Do

Support pork producers that have committed to transitioning from CO2 stunning
Ask retailers about stunning methods used in their pork supply chains
Advocate for regulatory timelines requiring transition to lower-aversion stunning
Support research into cost-effective inert gas stunning system designs
Choose higher welfare certified pork that includes stunning method standards
Engage with food industry campaigns for humane slaughter commitments