Controlled atmosphere killing
Controlled atmosphere killing (CAK) is a method for slaughtering animals such as chickens by placing the animals in a container in which the
nitrogen are important components of a painless gassing process which seem to cause no pain, and for this reason many consider it more humane
than other methods of killing.
Portable units are available. Controlled atmosphere stunning has been used both within processing plants and on-farm for euthanizing poultry. One
portable unit type that costs US$2,500 can be pushed down the aisles of a barn, with 200–250 hens per load being placed inside a CO2 enriched
chamber. Hens are unconscious within 20 seconds of being in the chamber.