Winter 2004 2005 Poultry Press << Previous - Next >>

Scientific Expert Urges Less Cruel Method of Killing Chickens and Other Birds; McDonald’s is Considering This Method

“I think the waterbath has to be replaced. Effectiveness of the stun cannot be determined and it causes inevitable pain.” – Dr. Mohan Raj

For UPC’s detailed summary, visit:

On December 16, 2004, Dr. Mohan Raj gave a seminar on the “Welfare, Economic and Practical Implications of Gas Stunning Prior to Poultry Slaughter” at the US Department of Agriculture. Dr. Raj is Senior Research Fellow in the Farm Animal Division of the School of Clinical Veterinary Science at the University of Bristol in the United Kingdom. Dr. Raj said, in sum:

The purpose of stunning is to “perform slaughter without causing avoidable fear, anxiety, pain, suffering, and distress.” The standard poultry industry method of dragging shackled birds head down through a cold salted electrified waterbath trough, used because it is “simple and cheap,” is “not conducive to good welfare.”

For example, over 90 percent of birds flap their wings due to the pain of being shackled, and evidence shows that birds suffer complex pain in being electrically “stunned.” Birds are unlikely to be rendered unconscious or pain-free, according to EEG criteria for unconsciousness and insensibility. Since physical signs like absence of breathing (apnea) are the same in properly and improperly stunned birds, these signs cannot accurately indicate the subjective condition of an electrically “stunned” bird.

By contrast, gaseous stunning based on the use of argon or nitrogen – Controlled Atmosphere Stunning (CAS) – can “eliminate the problems inherent in multiple-bird waterbath electrical stunning.” The birds are stun/killed in the crates prior to shackling. More than 30 percent carbon dioxide (CO2) is not recommended, however, as birds show aversion to CO2 by gasping, shaking their heads, stretching their necks to breathe, and showing signs that in humans are associated with pain and panic. Both neck-cutting without stunning and inhalation of carbon dioxide are “distressing and inevitably painful.”

However, birds exposed to argon/nitrogen-based gases do not show aversion because argon and nitrogen induce a state of anoxia (lack of oxygen), rather than the suffocation caused by carbon dioxide. Whereas birds have chemical receptors in their lungs that are acutely sensitive to CO2, they do not have receptors to detect argon, nitrogen, lack of oxygen (anoxia), or reduced oxygen (hypoxia). For this reason, they do not suffer the pain and panic caused by exposure to CO2.

From a practical standpoint, suppliers of CAS systems perform thorough risk assessments and ensure the health and safety of operators, and CAS gases are already being used in modified atmosphere packaging of foods. Equipment manufacturers and poultry producers should “share cooperate responsibility for ensuring welfare.”

However, corporate responsibility is not being exercised under the current electricity-based system, which is inherently inhumane. Controlled Atmosphere Stunning has “meat quality” benefits as well as welfare benefits, but “If the humane goal fails, it doesn’t matter what the meat quality is.”

“Nearly every chicken responded with screams and violent physical reactions from the moment they were grabbed by workers and as they went through the line. The screaming of the birds and the frenzied flapping of their wings were so loud that you had to yell to the worker next to you, who was standing less than two feet away, just so he could hear you.” –

“Working Undercover at Perdue,” The Abolitionist Winter 2004/2005. Magazine of Compassion Over Killing

  • McDonald’s, the world’s largest fast food company, is considering requiring its suppliers (Tyson Foods and others) to use the system recommended by Mohan Raj. The company said it will post the results of its analysis by June 30, 2005. Please write a polite letter to McDonald’s urging that they adopt the Controlled Atmosphere Stunning technology that KILLS the birds in the transport crates, so there is no chance of the birds regaining consciousness ever again.

James A. Skinner, CEO
McDonald’s Corporation
McDonald’s Plaza
Oak Brook, IL 60523
Phone: 630-623-3000
Fax: 630-623-5004

Winter 2004 2005 Poultry Press << Previous - Next >>