Carbon dioxide gas stunning is the dominant pig slaughter method - welfare evidence shows it is aversive and alternatives including high inert gas mixtures are more humane.
CO2 pig stunning welfare is one of the most significant and addressable welfare issues in commercial pig slaughter. The evidence that CO2 is aversive - causing panic and distress before unconsciousness - is robust and scientifically uncontested. Pigs experience approximately 15-30 seconds of distress before losing consciousness. Inert gas mixtures provide similar efficacy with dramatically less distress. The welfare case for transitioning from CO2 to inert gas stunning is clear; the barrier is capital investment and industry coordination. Consumer demand for higher welfare standards that specify stunning method and regulatory pressure for capital investment support are both needed.