UPC’s news release "Humaneness of Killing Birds with Carbon Dioxide is Disputed by Science" can be read online at:
When Alberta Egg Producers recently announced support for a system of destroying chickens by dumping hundreds at once into bins holding 650 birds and killing them with carbon dioxide, United Poultry Concerns issued a news release (3/30/05) challenging the "humaneness" of CO2 because CO2 induces painful suffocation in birds and "therefore should be avoided," according to poultry expert Dr. Mohan Raj of the University of Bristol in England. By contrast, the gaseous stun/kill system based on the use of the inert gases argon or nitrogen, known as Controlled Atmosphere Stunning, is said to eliminate or greatly reduce the suffering caused by pure CO2.
In "New hen killing method developed" (4/21/05) The Western Producer cited Alberta Agriculture animal welfare specialist John Church’s claim that the CO2 system "can be used on the farm for old laying hens" and "expanded if flocks had to be removed quickly because of a disease outbreak, such as avian influenza."
However, Calgary bureau writer Barbara Duckworth points out in her article that "Not everyone believes the new method of killing chickens is better. In a news release a group called United Poultry Concerns, which promotes compassionate treatment of domestic fowl, said it’s unlikely the killing is as quick and painless as Church claims. Pointing to a British study describing the effects of CO2 on the body, the group said the gas induces breathlessness which causes slow, painful suffocation. ‘The system may be cost effective, but it cannot be called humane,’ said Karen Davis, president of United Poultry Concerns.’" – The Western Producer April 21, 2005 (www.producer.com).