Controlled-atmosphere killing is a U.S. Department of Agriculture (USDA)-approved slaughter method that is currently used to kill 75 percent of turkeys and 25 percent of chickens in the United Kingdom and 10 percent of all birds in the European Union. CAK removes oxygen from the birds' atmosphere while they are still in their transport crates. The birds are not "gassed" (i.e., asphyxiated); they die from lack of oxygen, or anoxia, which is a painless process. CAK eliminates the numerous animal welfare, economic, and worker-safety issues associated with electric immobilization:
* With CAK, birds are dead before they are removed from their crates, shackled, bled, and scalded in defeathering tanks. Accordingly, these stages do not hurt the birds, damage or contaminate their carcasses, or pose a risk of injury to workers.
* With CAK, workers never handle live birds, so there are no chances for abuse. Worker ergonomics and safety are vastly improved. Lights can be kept bright, the air stays clean, and workers do not need to struggle with flapping, scratching, defecating, and vomiting birds.