Decompression: A New Way to Torture Chickens and Turkeys
An Animal Rights Article from


From United Poultry Concerns UPC)
April 2011

Cause of death in one treatment: simultaneous crushing of both lungs. . . . “Low, guttural moaning” of dying chickens not considered a vocalization for “scoring” their “humane” experience.

In Fort Smith, Arkansas, a chicken slaughter company called OK Foods has introduced a decompression technology called “low atmosphere pressure system” (LAPS). Guided by poultry researchers at Mississippi State University who are conducting LAPS experiments on young chickens, they’re calling the decompression of chickens “humane.”

Fort Smith is a town where a chicken slaughter and processing company called OK Foods is located, and the saloon strip is where its workers hang out after work. OK Foods is where a decompression technology called “low atmosphere pressure system,” or LAPS, was commercially introduced in 2010 under the guidance of poultry researchers at Mississippi State University who are conducting LAPS experiments on young chickens and calling the decompression system “humane.”

As described in a May 7, 2009 U.S. patent application for a LAP decompression system, the birds are placed in a sealed cylindrical chamber and the pressure in the chamber “is reduced at a continuous rate to a target decompression pressure for a period of time until a state of death is obtained. The low atmosphere pressure slaughter is more humane than traditional slaughter techniques and results in excellent meat quality.”

The “traditional slaughter techniques” refers to the standard commercial slaughter plant method of dragging chickens, turkeys, ducks and other birds, clamped by their feet upside down on a conveyer belt, through cold, salted, electrified water, designed to paralyze the muscles of their feather follicles in order to loosen their feathers and immobilize them on the assembly line, prior to cutting their throats with electric blades. Contrary to the poultry industry’s claim that electrical stunning is “humane,” it has been established for decades that the birds are excruciatingly tortured with the electricity, which immobilizes them in total agony.

The Mississippi State research team says their LAP decompression system is also more humane than the system of sealing chickens and turkeys in chambers filled with varying combinations of carbon dioxide, argon, nitrogen, and oxygen. These gases, according to the LAPS patent application, can produce “grand mal seizures in the birds, suggestive of extreme pain.” (A gas “stun/kill” method is provisionally supported by some animal welfare proponents as being “less cruel” than the paralytic electrified waterbath, which, given a choice, is probably true.)

The American Humane Association supports LAPS decompression of poultry. By contrast, the American Veterinary Medical Association calls decompression “unacceptable for euthanasia.” The AVMA Guidelines on Euthanasia, June 2007, explains: 1) decompression can occur at a rate that causes “pain and distress attributable to expanding gases trapped in body cavities.” 2) Young animals can tolerate oxygen deficiency for longer periods than older animals, thus taking longer to die. 3) Accidental recompression can occur whereby an animal injured by decompression regains consciousness. 4) Bleeding, vomiting, convulsions, urination, and defecation can occur in “unconscious” animals.

Decompression Sickness

Decompression sickness is a collection of symptoms arising from the decompression of a body as it is being depleted of its oxygen supply, causing gases that are normally dissolved in solution in the blood to form painful gas bubbles. Depending on the rate of decompression and other factors, these bubbles disrupt cells, block circulation, compress and stretch blood vessels and nerves, and cause “barotrauma.” Barotrauma is an injury to the middle ear, sinuses, gastrointestinal tract and lungs resulting from the body’s inability to equalize its internal air space pressure with the reduced pressure surrounding it. In Disaster Medicine, Hogan and Burstein state that in the process of being decompressed, “The ears and paranasal sinuses may become exquisitely painful from sudden overpressurization” of the gases trapped within.

In humans, decompression sickness is a risk for underwater divers rising to the surface from deep water below and for aircraft passengers ascending to thinner air. Many people have experienced the painful “crackling” in their ears as the airplane mounts to higher altitudes. Fortunately technology, unless it malfunctions, prevents further pain and distress.

But imagine that, instead of being protected from decompression trauma, you are locked in a cylindrical drum like the one pictured here, as the air is being sucked out while you die. This is the experience the Mississippi research team and the American Humane Association are calling a “humane” death for 6-week old chickens, and that the LAPS patent application recommends for every type of bird killed for human consumption: “The methods of the present disclosure may be adapted for use on any type of poultry, including, but not limited to, chickens, turkeys, quail, geese, ducks, ratites, and combinations thereof.”

Recall that among its objections to decompression, the AVMA lists the ability of younger animals to withstand oxygen deficiency for longer periods than older animals, causing them to die more slowly, yet the LAP system at Mississippi State and OK Foods is purposely designed to decompress birds who are only a month and a half old – the average age at which chickens are slaughtered for human consumption. All birds, from turkeys to quails killed for human consumption, are YOUNG.

decompression chamber

Decompression of Homeless Shelter Animals

The September 2010 edition of Animal People has an article about the American Humane Association’s approval of decompressing chickens in slaughter plants. Animal People points out that the language of the AHA’s 2010 LAPS endorsement recalls an article, published in 1950, through which the association endorsed decompressing homeless dogs and cats to death for more than 20 years. Notwithstanding, in 1972 the city of Berkeley, California banned decompression as inhumane. Other cities followed, and by the end of 1985, Animal People says “decompression was no longer used to kill shelter animals anywhere in the U.S.”

However, chickens and other birds defined as poultry and destined for slaughter have no refuge from the extremities of torture in the U.S. or anywhere else in actual practice. Birds in the United States are excluded from federal Animal Welfare Act regulations, and poultry are excluded from the Humane Methods of Slaughter Act – neither Act protects the animals it covers anyway. And as I note in Prisoned Chickens, Poisoned Eggs on page 151, the European Union, despite its reputation as a paragon of farmed animal welfare progress, allows among other cruelties a vacuum chamber “for the killing without bleeding of certain animals for consumption belonging to farmed game species (quail, partridge, and pheasant).” The birds are “held in groups in transport containers which can be placed in the vacuum chamber designed for that purpose.” When I asked animal slaughter researcher, Mohan Raj, what birds in a vacuum chamber are likely to experience, he said the loss of pressure would be “extremely painful” to their ears.

Decompressing Chickens for Human Consumption

An expert in bird physiology at high altitudes, Dr. Ole Naesbye Larsen, says rapid decompression will likely cause a bird’s eardrums to bulge and rupture. The ears of birds are extremely sensitive, and I’ve noticed how chickens bred for meat production, especially, will often shake their heads repeatedly in the presence of high pitched music, as if it hurts their ears. Birds entering a commercial slaughter plant come from densely polluted poultry houses. They suffer as a result from respiratory infections that are likely to intensify the excruciating pain produced by their rupturing eardrums, collapsing lungs, and expansion of gases in their bodies in the decompression chamber.

The researchers gloss over the subjective details of decompression. They distinguish between “rapid” versus “slow” decompression to argue that “slow” decompression is “humane,” but what exactly is “slow”? The birds are subjected to varying rates of decompression in numerous experimental treatments. Cut through the lingo and it appears the chickens are taking up to 4 minutes to be pronounced dead, and some of them are not dead even by then. Whatever the researchers decide, when it comes to commercial slaughter plant implementation, processing speed will be dictated by economics – exactly as it is now.

Watching the birds die through infrared monitors, the researchers drop their engineering vocabulary to report euphemistically, for example, that in one of the experiments, “only 2 birds exhibited wing flapping as a part of the death process; the other birds simply lay down and died peacefully.” They falsely equate the inability of the birds to stand or hold up their heads (“loss of posture”) with slipping comfortably into unconsciousness (“died peacefully”) similar to the way the poultry industry and its research teams since the 1930s have equated paralytic immobility with insensibility in birds dragged through electrified water in conventional slaughter plants. But these perceptions are deceptive. As if all this isn’t enough, here is how the researchers prepare the chickens for the LAPS experience they’re about to undergo in “Example 3”:

To begin, electrodes were attached to the skin of 56 broilers so that a Type II electrocardiogram (ECG) based on Einthoven’s triangle could be recorded. Additional electrodes were attached to skin overlying the skull at the base of the comb of the bird to record electrical activity of the brain as an electroencephalogram (EEG). The electrodes were connected to a telemeter which sent radio waves to a receiver that was hard wired to a PC-data acquisition system. The birds were placed one at a time into the decompression chamber described in the Test Methods section, and the pressure was lowered to 21.4 kPa (23.57 inHg gauge) over a lapse time of 37 seconds. The low pressure was maintained for 50 seconds (hold time).

Cause of death: “simultaneous crushing of both lungs.”


The decompression experiments described in the patent application and the Journal of Applied Poultry Research are being conducted simultaneously with electricity experiments, gassing experiments and countless other experiments that will continue throughout the world as long as people continue to eat animal products. Experimenting on chickens and other “food” animals is as much a part of the animal production industry as slaughter plants are. The only way to end the suffering and abuse is to stop eating animal products, adopt a compassionate vegan diet, and get others to join you. The alternative is endless repetitions of merciless cruelty and helpless suffering of the type depicted in the LAPS patent application:

General observations of slaughter under the various treatment conditions were as follows. At the onset of decompression, most birds were in the sitting position. Some birds would stand up as soon as air started exiting the chamber. Within a few seconds, some birds would exhibit one or two head shakes, defecate, raise their contour feathers; all birds became ataxic [unable to coordinate their muscles in voluntary movement], and then lost postural balance and became recumbent on the floor of the cage, either lying on their sides or backs. At this stage, flapping of the wings began by some birds accompanied by a low, guttural moaning in all treatments, except Treatment 3. It should be noted that the moaning was not considered a vocalization for purposes of determining the subjective slaughter score.

Please remember these birds and how they died. Remember how they are dying every single day, tortured and afraid, helpless and alone at the hands of experimenters and slaughterers without mercy, merely so people can eat them. Burn your knowledge of their suffering into the brain of everyone you know. Every bite of a bird is a mouthful of misery. VEGAN IS THE ONLY SOLUTION.


  • Animal People , “American Humane Association approves decompressing chickens,” Sept. 2010.
  • AVMA Guidelines on Euthanasia , American Veterinary Medical Association, June 2007, p. 35.
  • Cheek, et al. “New Method for Humanely Stunning and Slaughtering Poultry Using Controlled Low Atmospheric Pressure,” United States Patent Application Publication, May 7, 2009.
  • Davis, Karen, “Decompression – now the AHA-approved way to kill chickens,” Animal People, March 2011, p. 4.
  • Davis, Karen, Prisoned Chickens, Poisoned Eggs: An Inside Look at the Modern Poultry Industry, Book Publishing Company, 2009.
  • “Decompression illness,” Wikipedia.
  • Heckman, Kellie, “A Review of the Use of Low Atmospheric Pressure as a Means of Slaughtering Poultry,” PETA, Feb. 2009.
  • Hogan, David E., and Jonathan L. Burstein, eds, “Mechanical Injury with Rapid Decompression,” Disaster Medicine, 2007.
  • Pulley, Stephen A., “Decompression Sickness,” EMedicine, Sept. 17, 2009.
  • “Stepping Up: A revolutionary broiler stunning system pushes OK Foods into new territory,” Meatingplace, Oct. 2010.
  • Vizzier-Thaxton, et al., “A new humane method of stunning broilers using low atmospheric pressure,” Journal of Applied Poultry Research, 19:341-348, 2010.

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