The science is in, and it shows that controlled-atmosphere stunning (CAS) offers no significant welfare advantage over conventional low-voltage electrical stunning in the commercial processing of chickens.
Behind the first-ever evaluation of CAS at the commercial level are McDonald's Corp. and two of its chicken suppliers: Tyson Foods Inc. and Keystone Foods LLC.
CAS uses a gas such as carbon dioxide to render chickens and other poultry unconscious and insensible to pain prior to slaughter. The conventional technique United States poultry processors employ uses low-level electrical stunning to do the same thing.
Animal welfare experts have long had mixed views on which stunning practice is more humane. The animal welfare community itself has even been divided on the matter.
"The research around CAS was incomplete, so we were interested in participating in this study to test this technology and better understand its potential to improve animal welfare," said Dr. Ken Opengart, who oversees Keystone's animal welfare practices.
"Testing these practices in a commercial environment was critical to understanding the issues," said Dr Kellye Pfalzgraf of Tyson.
The two-part study looked specifically at the pros and cons of each stunning method at the commercial level, said Todd Bacon, in quality systems for McDonald's US supply chain.
He noted that the alpha phase focused on the methodology and equipment itself - understanding the right mixture and administration of gases to stun effectively while monitoring the bird reactions during the process.
The beta test, he said, incorporated what was learned from the alpha phase to further test the best CAS process at the commercial scale in production.
The study involved installing CAS equipment in a commercial setting and monitoring for a period of 16 production days. During the process, Bacon said a number of different factors were measured, including animal welfare and handling, carcass yield and product quality.
According to Bacon, studying the animal welfare implications of these practices isn't a new focus; McDonald's has been discussing and learning about the technologies for years.
"This study aligns with our vision of a sustainable supply chain that takes into consideration the ethical, environmental and economic impact," said Bob Langert, McDonald's vice president of corporate social responsibility.
Langert said McDonald's continuously monitors evolving research and technology with its US Animal Welfare Council, other independent experts, its own global supply chain experts and key poultry producers around the world, and doing that allows McDonald's to assess new and improved systems as they become available.
Langert said the absolute worst thing the company could do was make decisions that were not based on facts and science.
Globally, McDonald's continues to support its chicken suppliers' use of both CAS and electrical stunning. This latest evaluation confirms that it is the proper thing to do at this time, Langert explained.
As in most parts of the world, no large-scale chicken producers in the US currently use the CAS method.
In Europe, about 70 per cent of chicken is from suppliers using electrical stunning, and the remainder comes mostly from those using CAS.
The recent work by McDonald's follows a white paper the company prepared on CAS in mid-2005 that also concluded that substantial evidence did not exist at the time to warrant a switch to CAS.
"This work was to review what we're doing today and what we should be doing tomorrow, and it's part of our continuous improvement process that will continue on," said Bacon.
While the Humane Society of the United States (HSUS) and People for the Ethical Treatment of Animals (PETA) are opposed the conventional electrical stunning practice, the American Humane Assn (AHA) does not endorse one method over another.
"We believe that humane slaughter of food animals must be preformed using the best available science and in a manner that causes minimal or no distress to the animals," AHA president Marie Wheatley said. "We are not aware of any science-based, conclusive evidence that the distress chickens experience in existing electric stunning methods is either greater or less than that with gas anesthesia induction. Any claim that CAS is more humane is simply not founded on current science and should not be forced on the industry."
HSUS and PETA are of the belief that the conventional electrical stunning practice leaves the birds alive when presented to cutting instruments. Both groups continue to encourage retailers to switch to poultry processed using CAS.
PETA maintains a "McCruelty ... I'm hatin' it" campaign on its web site that uses adult and kid-friendly versions of electronic games, videos and graphics to depict what it calls the "horrible deaths" of chickens processed for McDonald's restaurants.
According to the National Chicken Council, conventional electrical stunning normally occurs by bringing the birds into contact with electrically charged water, rendering them unconscious and insensible to pain. Moments thereafter, the chickens are presented to a blade that opens an artery in their necks, resulting in rapid death.
The American Association of Avian Pathologists and American College of Poultry Veterinarians have said the conventional process is 99.95% effective.
While some liken CAS to "being put to sleep," Dr. Bernard Rollin, a noted specialist on animal welfare, believes there is no distress as severe as the feeling of being unable to breathe. So, while CAS creates unconsciousness, Rollin said, "there must be a period when the animal feels a sense of suffocation, (and) for this reason, I do not accept CAS as a humane method of euthanasia."
Temple Grandin, an animal welfare expert and a member of McDonald's US Animal Welfare Council, said: "There is always a need for sound science around these important animal welfare considerations, and regardless of the method, good management practices, such as those that McDonald's requires of its suppliers, are critical to humane treatment of animals."
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