Stunning before slaughter is the most important single welfare intervention for the billions of chickens slaughtered annually. Method choice determines welfare outcomes at enormous scale.
Water bath electrical stunning requires live shackling of conscious birds upside down before stunning, causing distress and pain before unconsciousness is achieved. When stunning parameters are incorrect, birds enter the scalding tank conscious. Controlled atmosphere systems allow birds to lose consciousness while still in transport modules, eliminating live shackling distress. The scale of broiler slaughter — roughly 200 million birds per week in the US alone — means that even small improvements in stunning welfare represent enormous aggregate benefit. The transition to CAS/CAK represents one of the most impactful achievable welfare improvements in animal agriculture.