Pre-slaughter stunning is essential to minimise suffering at the point of killing in pigs. The method and effectiveness of stunning significantly affects the welfare of hundreds of millions of animals annually.
The manner of death for over a billion pigs annually is a major animal welfare issue. Electrical stunning, when properly applied, achieves rapid unconsciousness and is the most humane widely available method. High-concentration CO2, despite being the most commonly used commercial method, causes a period of aversive experience during induction that the industry has resisted replacing with less distressing alternatives. Slaughter quality assurance programmes that monitor stunning effectiveness have demonstrated that failure rates can be reduced significantly with training, equipment maintenance, and incentive structures.