Excerpt from Chapter Five, “The Death,” PRISONED CHICKENS, POISONED EGGS: AN INSIDE LOOK AT THE MODERN POULTRY INDUSTRY by Karen Davis, PhD. New Revised Edition, 2009.
Stunning is a procedure that induces an unequivocal pathological brain state that is incompatible with the persistence of consciousness and sensibility in order to perform slaughter without causing avoidable fear, anxiety, pain, suffering and distress. . . . The stunning method itself should not be stressful. – Dr. Mohan Raj, USDA Seminar, December 16, 2004
Birds slaughtered in the United States are neither stunned (rendered unconscious) nor anesthetized (rendered pain-free). Pre-slaughter stunning is not required by law and is not practiced, despite the use of the term “stun” to denote what is really immobilization of conscious birds. In practice, “stunning” is monitored only for efficient bleedout. The Poultry Products Inspection Regulations of the U.S. Department of Agriculture merely states that “Poultry shall be slaughtered in accordance with good commercial practices in a manner that will result in thorough bleeding of the carcasses and assure that breathing has stopped prior to scalding” (PPIA).
There are three main methods for immobilizing birds to prepare them for slaughter, or neck-cutting: (1) chemical immobilization, in which a mixture of gases is administered, such as carbon dioxide and reduced oxygen using an inert gas such as argon or nitrogen to stabilize and improve dispersal of the main gas; (2) mechanical, as by debraining, in which the medulla of the brain is pierced directly through the eye, a traditional farming practice prior to the development of electrical stunning in the 1930s; and (3) electrical, the standard commercial method in which a live current is driven through the bird by means of an electrified knife or plate, or electrified water to which sodium chloride (salt) has been added to improve conductivity of the charge.
Pre-Slaughter Electrical Waterbath “Stunning”
The complexity of multiple bird waterbath stunning is not conducive to maintaining good welfare. Effectiveness of the stun cannot be determined. The method, widely practiced because it is simple and cheap, cannot be controlled. You can’t control the amount of electrical current flowing through a bird. You can’t harmonize electrical resistance in broiler chickens. The waterbath has to be replaced. – Dr. Mohan Raj, USDA Seminar, December 16, 2004
The electrified cold-salted waterbath is the standard method used in the large commercial slaughter plants to immobilize birds prior to cutting their throats. The method was developed in the twentieth century to perform strictly commercial functions rooted in farming practices such as those described in a 1937 manual, Marketing Poultry Products, by Benjamin and Pierce, who wrote: “It is necessary that the brain be pierced with a knife so that the muscles of the feather follicles are paralyzed, allowing the feathers to come out easily (139).
After the birds have been manually jammed into the moveable metal rack that clamps them upside down by their feet in the “live-hang” room, they are dragged through a 12-foot-long electrically-charged water-filled trough, called a stun cabinet, for approximately seven seconds. Between 20 and 24 birds occupy this cabinet at a time. One hundred and eighty or more birds pass through it every minute (Bilgili 1992, 139).
The electrically-charged waterbath is not designed to render birds unconscious, or even pain-free, but to slacken their neck muscles and contract the wing muscles for proper positioning of their heads for the automatic neck-cutting blades. It is also designed to prevent excessive struggling of the birds as the blood drains from their necks, to promote rapid bleeding (under 90 seconds), and loosen the birds’ feathers after they are dead. During electrical water-bath stunning, currents shoot through the birds’ skin, skeletal breast muscle, cardiac muscle, and leg muscles causing spasms and tremors, reducing heartbeat and breathing, and increasing blood pressure. The birds exit the stunner with arched necks, open, fixed eyes, tucked wings, extended rigid legs, shuddering, turned up tail feathers, and varying amounts of defecation (Bilgili, 136, 142).
Problems identified with this method include birds missing the stun bath by raising their heads to avoid it (as, for example, in the case of the “one-leggers” described above), and shocking of birds splashed by water overflowing at the entrance end of the stun cabinet. Electrical resistance of the circuits can vary between and within a single slaughter plant reflecting differences in stunners and circuits, and a wide range of other variables including the birds’ own bodies. According to Bilgili, “The abdominal fat tissue has the greatest resistivity of all tissues measured. The high variation observed in resistivity of the skull bone indicates that birds with thick and dense skull bones [spent laying hens and breeding fowl, because of their age] are most likely to be inadequately stunned” (140-141).
Evidence notwithstanding, the U.S. Department of Agriculture’s Food Safety and Inspection Service (FSIS), in charge of the approximately 320 poultry slaughter plants under Federal Inspection in 2006, claims that most birds under inspection are slaughtered “humanely.” However, FSIS does not keep a list of “humane” methods or provide documentation verifying that most birds are rapidly and effectively rendered insensible to pain and suffering in the process of being killed. H. Russell Cross, FSIS Administrator in 1992, wrote in response to my inquiry: “The statement that ‘birds are effectively stunned before slaughter’ is based on observations of Food Safety and Inspection (FSIS) personnel.”
An example of a published FSIS study is “A Survey of Stunning Methods Currently Used During Slaughter of Poultry in Commercial Poultry Plants” (Heath 1994). Cited at a Congressional Subcommittee hearing in 1994 as showing “widespread use of humane methods of slaughter in the Nation’s [poultry] slaughter plants,” this 1992 survey was conducted entirely by phone and fax!
Birds are Not Stunned
The typical amperage used in stunning by our pulsating direct current pre-stunner is approximately 12 to 15mA . . . . If the reading is 200mA, with 16 birds in contact, there would be an average of 12.5mA per bird. – Wayne Austin, Simmons Engineering Company
In reality, so-called “humane” electrical stunning of poultry is regarded as incompatible with the goals of commerce. High levels of current are said to interfere with plant efficiency and to cause hemorrhage – a “bloody bird” (Kuenzel). Hemorrhaging of the fragile capillaries of the increasingly younger and heavier birds being slaughtered has been cited as a reason to lower the electrical currents even more (Bowers 1993b). While research suggests that for electrical stunning to produce unconsciousness chickens should receive a minimum current of 120 mA per bird, and that currents under 75 mA per bird should never be used (Gregory and Wotton, 219), chickens slaughtered in the United States are being given weak currents ranging between 12 mA and 50 mA per individual bird. As researcher Bruce Webster told a conference on handling and stunning, “Industry is trying to stay at 25 mA and below due to hemorrhaging” (Webster 2002).
Electrical Paralysis of Conscious Birds
For death to be painless and distress-free, lost of consciousness should precede loss of motor activity (muscle movement). Loss of motor activity, however, cannot be equated with loss of consciousness and absence of distress. Thus agents that induce muscle paralysis without loss of consciousness are not acceptable as sole agents for euthanasia. – AVMA, 2000 Report of the AVMA Panel on Euthanasia, 675
Since physical signs like the 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. – Dr. Mohan Raj, USDA Seminar, December 16, 2004
All it [the stunner] does is paralyze the muscles. . . . In Tyson’s own words to the workers, “It makes the plant more efficient.” They never said anything about “humane.” – Virgil Butler, “Clarification on Stunner Usage,” 2004
According to researchers, a major problem with electrical stunning, even under “ideal” conditions, is that birds who are stunned (rendered unconscious) and birds who are merely paralyzed look the same (Gregory 1986; Boyd, 224). A bird or a mammal may be unable to move, struggle, or cry out while experiencing intense pain and other forms of suffering including the inability to express outwardly a response to pain perception. As Nobel laureate, Professor A.V. Hill, explained about the electrocution cabinets being used for dogs and cats in the 1920s, these cabinets “were likely to cause great pain although this would be masked by muscular paralysis.” The apparently unconscious or dead animal was most likely to be “fully conscious and in agony for some time before unconsciousness and death supervened” (WFPA, 12).
This gives an idea of what is happening to billions of birds in the slaughterhouses – bearing in mind that unlike the dogs and cats cited above, poultry are not intended to be electrocuted (killed) but only shocked into paralysis. Even after a century of experiments in controlled laboratory experiments, scientists disagree over how to determine whether a bird is truly stunned and not merely immobilized (paralyzed) and whether a bird is in pain. Various indicators have their proponents: visual, auditory, evoked versus spontaneous somatosensory response, physical activity, brain waves, breathing, etc. (Boyd). Imagine the feelings of the chicken or turkey of whom it is recommended that “A good rule of thumb for checking for an adequate [electrical] stun is to remove the bird immediately after the stun and place it on the floor. The bird should be able to stand within 1-2 minutes” (Wabeck).
British law requires that livestock and poultry must be rendered instantaneously insensible to pain until death supervenes. Poultry slaughter expert, Neville Gregory, said the law should delete the reference to pain and simply read, “Rendering the animal instantaneously insensible until death supervenes,” because following electrical “stunning,” in addition to the suffering induced by the electric shocks, one can have analgesia whereby there is conscious perception of non-painful but highly distressing stimuli including gagging, breathlessness, smell of blood, fear and apprehension (Gregory 1993).
In other words, one can have dreadful experiences even without being in physical pain. An example is the experience of breathlessness, or “dyspnea.” According to the American Pain Society, “The word dyspnea subsumes a variety of unpleasant respiratory sensations described by terms such as chest tightness, excessive breathing effort, shortness of breath, and air hunger.” According to the Society,
There are few, if any, more unpleasant and frightening experiences than feeling short of breathe without any recourse. . . . For instance, a strong perception of a need to breathe causes diving animals to surface and causes all animals to struggle to remove external obstruction to air passages. (Banzett and Moosavi, 1-2)
Responding to welfare concerns, some European companies have begun subjecting chickens and turkeys to amperages designed to induce cardiac arrest – a heart attack – in order to induce brain death prior to neck cutting and bleedout. Stopping the heart interrupts the flow of oxygenated blood to the brain resulting in a presumed loss of consciousness. Birds in a state of cardiac arrest may be further protected from the protracted agony of badly cut necks. Notwithstanding, as one slaughter operator states, “It is possible that the [electric] shock, even as it renders the bird unconscious, is an intensely painful experience” (Boyd, 223).
Post-Slaughter Electrical “Stunning”
In addition to pre-slaughter “stunning,” post-slaughter electrical shocking of the still-living birds is being experimentally and commercially conducted. U.S. researchers claim that while it will not improve bleedout, it will “calm [the bleeding and dying] birds and reduce the force required to remove feathers” (Bowers 1993a). According to an article in Poultry Marketing and Technology, “Post-slaughter stunning is mostly used on broilers weighing more than 7 pounds, light and heavy fowl, and turkeys. It is also recommended for processors cooking product for frozen entrees” (Bowers 1993b).
Thus, hanging and dying in the bleedout tunnel, after having their throats cut, the battered birds are guided automatically against an electrified ladder or a square plate and delivered a few final volts of electricity.
Neck-Cutting and Bleedout
Some nights I worked in the kill room. The killer slits the throats of the chickens that the killing machine misses. You stand there with a very sharp 6-inch knife and catch as many birds as you can because the ones you miss go straight into the scalder alive. You have to cut both carotid arteries and the jugular vein for the chicken to die and bleed out before hitting the scalder. . . . The blood can get deep enough to go over the top of a 9-inch set of rubber boots. I have seen blood clots so big that it took three big men to push them. You have to stomp them to break them up to get them to go down the drain. That can happen in just 2 ½ hours. We filled up a diesel tanker truck with blood every night in one shift. I have actually had to wipe blood clots out of my eyes. – Virgil Butler, “Slaughterhouse Worker Turned Activist”
The two methods most commonly used for cutting the blood vessels in the necks of chickens and turkeys are manual cutting, in which a knife is passed across the side of the neck at the joint with the bird’s head, and automatic neck-cutting, in which the bird’s neck is glided across a revolving blade – “a 6-inch meat saw blade that resembles a finishing blade for a circular saw” (Butler 2003c). Plants with automatic neck cutters may or may not have a manual backup should a bird miss the cutter. Britain passed a law in 1984 requiring manual backup of automatic cutters. However, there is no law in the United States.
The fastest way to produce brain death in chickens by neck-cutting is severing the two carotid arteries that supply the brain with most of its fresh blood, whereas the jugular veins carry spent blood away from the brain. Poor neck-cutting extends the time that it takes a bird to die. Worst is the severance of only one jugular vein, which can result in a bird’s retaining consciousness, while in severe pain, for as long as eight minutes. Most of the blood has to drain out of the body before the heart stops pumping blood to the brain through the carotid arteries. If both jugular veins are cut, brain failure occurs in approximately six minutes and the bird is in danger of regaining consciousness, especially if breathing resumes. If both carotid arteries are quickly and cleanly severed, the supply of blood to the brain is disrupted, resulting in brain failure in approximately four minutes. However, the carotid arteries are deeply embedded in the chicken’s neck muscles, and even more deeply embedded in the turkey’s, making them hard to reach (Gregory 1984).
Cutting the spinal cord is regarded as inhumane because it induces asphyxia – suffocation – rather than depriving the brain of blood, because the nerves that control breathing are severed within the spinal cord. Cutting the spinal cord interrupts the nerves connecting the brain with the bird’s body making it impossible for the bird to exhibit conscious awareness through physical expression. As with the use of electricity and paralytic drugs, a bird in excruciating pain or other distress will not be able to show it.
Slaughter Without “Stunning”: Ritual Slaughter, Live Bird Markets and Small Farms
Small slaughterhouses and farms often omit “stunning” in order to save money and because ritual slaughter excludes the practice. Typically, the birds are killed “by cutting the neck and incising one or more major vessels” (Heath 1994). This is often done after the bird has been shoved upside down into a killing cone with the bird’s head hanging out at the bottom. Instead of being electrically paralyzed, the bird is physically restrained. Jewish doctrine states than an animal must be uninjured at the time of killing, and stunning is classed as injury (Birchall, 46). The Vietnamese puncture a chicken’s throat and let the blood drain out slowly (Huckshorn).
Undercover footage of an ethnic slaughterhouse in Los Angeles shows chickens having their throats cut manually and being stuffed alive into bleedout holes by the employees. Blood-soaked chickens with partially cut throats try vainly to lift themselves out of the troughs into which more bleeding and writhing birds are casually flung before being picked up and shackled. Bleeding, flapping chickens fall off the line onto the floor – no one pays any attention (Farm Sanctuary 1991).
The United Poultry Concerns video, Inside a Live Poultry Market, shows footage obtained at the Ely Live Poultry market in the Bronx, in New York City. In the slaughter room, two pitiful brown hens stand together in a stainless steel sink while men slice the throats of other chickens and shove them into the bleedout holes. The dying birds’ legs pedal and thrash violently in the air. One slaughtered hen leaps out of the hole, alive, onto the floor. After a while, one of the slaughterers picks her up and shoves her back down into a bleedout hole, like he was stuffing garbage into a trashcan (UPC 2003a).
According to my Koran, animals have no voice. But you treat them like you treat yourself. – Riaz Uddin of the Madani Halal slaughterhouse in Queens, New York (Drake)
Ritual slaughter refers to “a method of slaughter whereby the animal suffers loss of consciousness by anemia of the brain caused by the simultaneous and instantaneous severance of the carotid arteries with a sharp instrument and handling in connection with such slaughter” (HMSA, Title 7 U.S. Code, Section 1902b)). Contrary to assertions, ritual slaughter (e.g., Kosher, Muslim) does not cause a humane death. Neck-cutting, even if done “correctly,” is painful and distressing (Raj 2004) and other problems have been identified. Researchers at the Food Research Institute in Britain showed that “in cattle brain activity sometimes persisted for some time after Shechita” (Jewish ritual slaughter), and that “sometimes the carotid arteries balloon within 10 seconds of being cut, causing an increase in blood flow to the brain, and so maintaining its activity” (Birchall, 46).
In practice, “ritual slaughter” – meaning the quick, clean severance of both carotid arteries carrying oxygenated blood to the brain – may not even be done. A New York State “Shopping Guide for the Kosher Consumer” states that the shocket [orthodox ritual slaughterer] severs the windpipe and jugular vein.” (Ratzersdorfer 1987). At an Empire Kosher slaughter plant in Pennsylvania, owned by the largest kosher slaughter operation in the world, one worker removes the birds from the crate and passes them through the opening in the wall to another worker who holds and positions the bird for the slaughterer. The slaughterer severs the windpipe, or trachea, which is filled with pain receptors, and a jugular vein, and inspects the bird. The second helper then hands the bird to another worker who hangs it on a convener belt. A Baltimore, Maryland journalist who toured an Empire Kosher plant wrote that “the chickens thrash desperately on the hooks” but was told this was just “reflex” (Oppenheimer, 46). As for the footage obtained at the Ely Live Poultry market in the Bronx, Dr. Mohan Raj said it was “deeply disturbing to see the slaughterman restraining conscious birds by folding back their wings and cutting their throats as though he was slicing a fruit or vegetable” (Raj 2005a).
In addition to the cruel slaughter, the British Farm Animal Welfare Council reported the often “callous and careless” treatment of birds in ritual slaughter markets, including throwing and ramming them into bleeding cones after their throats were cut and leaving rejected birds in transport crates overnight without food and water (Birchall, 46).
Spent Laying Hens and Small Game Birds
In the United Kingdom, spent laying hens are “stunned’ using electrical water bath stunners or inert gas mixtures, and there is a quail plant in which the birds are hung on a purpose-built shackle line and dragged through an electrical waterbath stunner (Raj 2005b). In addition, a European Union Council Directive allows a vacuum chamber to be used “for the killing without bleeding of certain animals for consumption belonging to farmed game species (quail, partridge and pheasant).” The birds are placed in an airtight chamber in which a vacuum is achieved by means of an electric pump. They are “held in groups in transport containers which can be placed in the vacuum chamber designed for that purpose” (Pickett). Regarding the vacuum chamber, Mohan Raj said that “it can be extremely painful to birds with blocked ear canals” (2005b)
Research on vacuum stunning is being conducted on broiler chickens by the U.S. Department of Agriculture’s Agricultural Research Service using a system claimed to be cheaper and faster than gas-based Controlled Atmosphere Stunning (CAS) systems. According to an article, it takes “about 30 seconds to pull the pressure down to about 20 percent of normal atmosphere pressure in the chamber, or 80 percent vacuum. Within 30 seconds at 80 percent vacuum the birds are dead” (O’Keefe 2007, 25).
In the United States, spent laying hens may or may not be electrically “stunned” and small birds such as quails and guinea fowl normally are not. It is claimed that electrical stunning would incur a financial cost through carcass damage and rejection because of easily fractured bones (Boyce). According to Bruce Webster, spent laying hens “struggle in the shackle and lift their bodies away from the stunner bath, reducing the probability of making good electrical contact with the stunner” They flex their necks, get splashed with electrified water, struggle more violently with the additional pain, and ride up on the bodies of adjacent birds (Webster 2007). A USDA survey of slaughter plant methods in 1991 showed that virtually all small birds including spent laying hens were “slaughtered without stunning by severing the carotid arteries or decapitation. Light fowl (93%) and geese (100%) were slaughtered primarily by severing the carotid arteries. No geese were electrically stunned” (Heath, 299).
As spent laying hens are much older than broiler chickens when they are killed and consequently have harder skulls, they require stronger currents to make them unconscious (however that is determined), making the whole problem of electrical stunning even more insurmountable (Bilgili, 141).
Gaseous stunning is intended to eliminate the problems inherent in multiple bird waterbath electrical stunning. – Mohan Raj, USDA Seminar, 2004
The twin problems of bone breakage and pre-stun shocks make controlled atmosphere stunning (gas stunning) an option that fowl processors should seriously consider for spent commercial laying hens. – Bruce Webster, 2007
In view of the intense suffering caused by electrical stunning, an increasing number of researchers say that gas stunning based on hypoxia (low oxygen) or no oxygen (anoxia) represents the best alternative to electrical stunning of poultry. Gas would eliminate the need for pre-slaughter shackling. It could be performed in the transport crates, reducing stress on both workers and birds. Some say a non-aversive inert gas such as argon or nitrogen is the least inhumane method for spent laying hens (Raj 2005c). Others cite the difficulty of pulling hens in a state of rigor mortis out of battery cages. Yet another difficulty is evenly distributing the gas from floor to ceiling in a huge building full of stacked cages (Berg).
From a welfare standpoint, not all gases are the same. The two main gas systems recommended to replace electrical stunning are carbon dioxide (CO2) and the inert gases argon and nitrogen. Carbon dioxide is the least expensive industrial gas which unfortunately favors its use by the poultry industry. Speaking at a USDA Symposium in 2004, Mohan Raj explained the welfare advantage of argon and nitrogen to stun-kill the birds in the system known as Controlled Atmosphere Stunning (CAS) or Controlled Atmosphere Killing (CAK). The latter term was coined by People for the Ethical Treatment of Animals to stress the importance of killing the birds outright with the gas to prevent them from waking up during the slaughter process.
Birds and other animals completely avoid, hesitate to enter or rapidly evacuate from an atmosphere containing high concentrations of carbon dioxide. . . . Animal Welfare scientists would agree that the humanitarian intentions of eliminating avoidable pain and suffering during water bath stunning would be seriously compromised by carbon dioxide stunning of poultry. – Mohan Raj, “Recent Developments in Stunning and Slaughter of Poultry,” 2006b
CO2 activates brain regions in both birds and humans that are involved in the perception of pain. It causes panic in response to the sensation of suffocation and breathlessness, or dyspnea, which occurs when the amount of atmospheric CO2 exceeds 30 percent. Inhalation of carbon dioxide is both painful and distressing, because birds, like humans, have chemical receptors (intrapulmonary chemoreceptors) that are acutely sensitive to carbon dioxide. This sensitivity produces an effort to expel the gas by breathing more rapidly and deeply, but breathing more rapidly and deeply only increases the intake of CO2, leading to suffocation. Ducks in particular have been shown to undergo an especially slow, agonizing death in CO2 chambers (EFSA).
An article in New Scientist had a disturbing report on the use of carbon dioxide by Ruth Harrison. The author of the influential book Animal Machines and a member of the Farm Animal Welfare Council in Britain said, “I used to be very much a proponent of CO2 stunning.” But a visit to a mink farm in Denmark, followed by inhaling the gas herself changed her mind. Regarding the gassing of day-old male chicks by the egg industry, which she once condoned, she said: “In my opinion, it is no better than the old practice of filling up a dustbin with them and letting them suffocate.” (Birchall, 47).
Argon and Nitrogen
Both neck cutting without stunning and inhalation of carbon dioxide are “distressing and inevitably painful,” according to Mohan Raj. In contrast, birds exposed to argon/nitrogen gases do not show aversion – they do not try to escape from or avoid the presence of argon or nitrogen, he says. The reason is that birds, like humans, have chemical receptors in their lungs that are acutely sensitive to CO2, but they do not have receptors to detect argon, nitrogen, lack of oxygen, or reduced oxygen. Therefore, according to Raj, they do not experience the pain, panic and suffocation caused by exposure to CO2.
In experiments in the United States and the United Kingdom, turkeys and chickens made fewer stops and retreats when argon was present while showing an increased tendency to stop when carbon dioxide was present. When CO2 levels are high (above 40%), birds gasp, shake their heads, and stretch their necks to breathe. But in the presence of argon, there is said to be little or no sign of birds gasping or stretching their necks to breathe. The small amount of head shaking in chickens in an argon chamber indicates that they are trying to “wake up,” rather than experiencing suffocation, as in a CO2 chamber, according to Raj.
However, birds do a lot of wing flapping that results in broken wing bones in the presence of argon or nitrogen. The poultry industry complains that broken wings can’t be marketed to consumers (Grandin 2005b). From an ethical standpoint, wing-flapping raises disturbing questions about the birds’ suffering. However Raj argues
that wing-flapping in the presence of these gases signals unconsciousness caused by the brain being starved of oxygen (Raj 2006b; Prescott 2006).
Adoption of Gas Systems
An amendment to U.K. regulations in 2001 allowed gas mixtures to be used in the slaughter of poultry. Approximately twenty-five European slaughter plants use some sort of gas system (Shane 2005). It is estimated that 75 percent of turkeys and 25 percent of chickens slaughtered for human consumption in the U.K. are killed using inert gas mixtures (nitrogen and/or argon) or a mixture of less than 30 percent carbon dioxide in the inert gases argon and/or nitrogen (Raj 2006b). Several major chicken and turkey slaughter operations, including Deans Foods, which slaughters 7,000 spent hens and breeding fowl per hour in Lincolnshire, England, use a nitrogen-based stun-kill system. Deans Foods it calls “the most welfare friendly system of stunning poultry available” (“Stunning advice”).
There is more resistance to replacing electrical “stunning” with gas-induced stunning of birds in the U.S. than in the U.K. The U.S. industry views the issue as having to “counter opposition from animal rights movements and extremist organizations” (Shane 2005). At the same time, opposition to the uncorrectable cruelty of electrical “stunning,” emphasized by United Poultry Concerns, PETA, and The Humane Society of the United States, has grown. In 2007, McDonald’s claimed to be awaiting further developments, ConAgra Foods was urging suppliers to adopt the CAS system, and Burger King announced a purchasing preference for chicken meat “from processors who employee controlled atmosphere stunning (CAS) systems” (O’Keefe 2007).
By 2007, a plant called MBA Poultry in Tecumseh, Nebraska was using a carbon dioxide-based CAS system to “stun” broiler chickens, and four U.S. turkey plants had adopted the CO2 system for male turkeys weighing around forty pounds. One of these, Dakota Provisions in Huron, South Dakota, is run by Hutterite colonies (one of the Anabaptist faiths along with the Amish and Mennonites) and slaughters 4 million male turkeys a year (O’Keefe 2006).
What About Carbon Monoxide (CO)?
Some people wonder carbon monoxide isn’t used. Carbon dioxide is a colorless, odorless, painless, deadly gas. When I asked Mohan Raj about this, he said that “CO can be used where available. For example, it was used in Belgium and Holland during 2003 avian influenza outbreaks. The problem is that a lethal concentration of this gas will affect all living creatures, not just humans who could be protected with breathing apparatus. Unlike argon or nitrogen, CO2 is explosive at 12.5% or more and therefore imposes an additional safety burden” (Raj 2007).
According to the American Veterinary Medical Association’s 2000 Report on Euthanasia, carbon monoxide induces loss of consciousness without pain and with minimal discernable discomfort, but is hazardous to humans precisely because it is highly toxic and difficult to detect. However, with properly designed ventilation systems, CO chambers, explosion-proof equipment, and commercial compression of the gas, CO can be used to kill dogs and cats (AVMA, 678-679). Nothing is said about birds, and it isn’t clear why the problems presented by carbon monoxide could not be worked out in a poultry slaughter plant.
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@ 2009 Karen Davis
From Chapter Five, “The Death,” Prisoned Chickens, Poisoned Eggs: An Inside Look at the Modern Poultry Industry. Revised Edition. Summertown, TN: Book Publishing Company, 2009.