FORT SMITH — Birds waiting to be slaughtered at the O.K. Industries plant on Sixth Street are “irreversibly stunned” before entering the processor’s automated line, where workers turn them into breaded, seasoned and marinated chicken products.

The Low Atmospheric Pressure System, which knocks out or kills the birds by lowering air pressure in a sealed chamber, is the only one of its kind in use in the country. The atmospheric pressure technology created by Hollis Cheek of TechnoCatch LLC in Kosciusko, Miss., has been in service at the plant full time since February.

O.K. Industries is hoping the technology will resonate with consumers who care about animal welfare in large scale commercial food production and with its customers in the fast-food industry.

The Humane Society of the United States has not endorsed an industry switch to the process but said the technology shows promise. The system is an alternative to electric stunning used by a majority of American processors and to carbon dioxide gas stunning, which is far less common and more expensive.

Executives with O.K. Industries, a privately owned holding company, said the method is one of the most innovative technologies to appear and they see it becoming the industry standard in less than a decade. They often refer to the stunning system as LAPS.

“By bringing awareness about LAPS to consumers we hope they will say, ‘This is the way we want birds processed,’” said Kevin McDaniel, vice president of production in the farms division.

The company declined to comment on how much it has invested in the technology. It does host processors from across the globe curious about the procedure. Recently, a delegation from South Africa traveled to Fort Smith see the setup.

In 2010, the method received endorsement from the American Humane Association in Englewood, Colo., a group that has been accused by some of pandering to meat producers.

Kathi Brock a spokesman for the association, defended the group’s support of Low Atmospheric Pressure System saying the group’s panel of advisers had access to good science.

“We do not take any position or adopt any standard without having good research,” Brock said.

A 2010 Journal of Poultry Science article authored in part by Yvonne Vizzier-Thaxton, formerly of Mississippi State University, and Karen Christensen, a researcher and director of technical service at O.K. Industries Inc., is the basis for the association’s approval.

Anne Fanatico, an assistant professor of poultry at Appalachian State University in Boone, N.C., said she doesn’t think the public knows much about stunning methods used in poultry processing or why some methods might be better than others. Or, even if the public cares to know, she said.

“But I think the American public will [care] if they learn about it,” Fanatico said.

“What O.K. Industries has going for it in talking about atmospheric stunning is an opportunity for learning,” she said

Today, most commercial processors hang the birds upside down before dipping them into electrified water to stun them. O.K. Industries also employs this method at its other plant, in Heavener, Okla.

In-plant stunning is eliminated with the new method. The chambers sit outside the building in the loading dock.

Forklift operators feed stackable, holding cages onto conveyer belts that lead to one of four large metal chambers. Each tube-like chamber can hold about 440 birds.

TechnoCatch describes its stunning device as a pressure and time control system that vacuum-reduces air in the chamber. Company representatives said each setup would be unique because processing businesses run their factories differently.

In outfitting the Fort Smith plant, McDaniel said the speed of the production line dictated four chambers because “there are 1,500 workers waiting to do their job down the line,” he said. “We need to keep the birds going.”

The chamber door closes at the push of a button by an O.K. Industries machine operator perched in a small observation deck. A computer monitor nearby displays black-and-white images from inside the chamber.

A recent batch of chickens wobbled with the initial drop in air pressure. About a minute later many flapped their wings before dying.

Birds are in the chamber for about four minutes.

“Once a certain pressure is reached the birds become insensitive to pain,” Cheek said during a telephone interview Tuesday. “The brain will shut down before the heart will.”

Proponents liken the process to hypoxia, a condition that pilots can experience when flying too high.

“You’re not seeing a death struggle because the bird doesn’t feel anything,” said Cheek.

TechnoCatch has worked closely with O.K. Industries and veteran poultry researcher Vizzier-Thaxton, the new director of the Center for Food Animal Well Being at the University of Arkansas at Fayetteville, to perfect its stunning technology.

Scientific studies on chickens during Vizzier-Thaxton’s tenure at Mississippi State University support Cheek’s observation. Brain-wave activity and stress hormone levels are two physiological indicators used to support the claim the method is humane.

Matthew Prescott, spokesman for the Humane Society of the United States said that while the initial science behind the method appeared promising, “there are some gaps in the science that we hope will be worked out before we consider advocating the industry switch to that method.”

The Humane Society considers the conventional electric stunning method unacceptable. Birds likely feel pain with an electric stun that’s administered before throat slitting and defeathering, Prescott said. More research about the brain-wave data and an additional “humaneness” test are needed before the group gives its stamp of approval, Prescott said.

People for the Ethical Treatment of Animals in Norfolk, Va., continues to advocate for controlled atmospheric killing, which is when oxygen is replaced with a nonpoisonous gas.

In 2011, the group put a proposal before shareholders asking the Springdale business to adopt the gas slaughtering method. The proposal did not pass.

Some anti-meat groups criticize the atmospheric method for blowing out chickens’ eardrums, which are said to be extremely sensitive, and for crushing lungs.

Karen Davis, president of United Poultry Concerns, a vegan group in Virginia, said she’s heard all the arguments before about how the method is humane, “but there’s a whole bunch of research that shows otherwise.”

Upon exiting the Low Atmospheric Pressure System chamber, the dead birds are dumped onto another conveyor system that sends the carcasses inside to a crew of 18 men who sort and hang them upside down. O.K. Industries officials say workers hang 20 birds a minute at its Fort Smith plant.

J.C. Mares, 35, of Fort Smith, said hanging limp birds is “more easy” than live ones. Workers such as Mares no longer have to deal with wriggling legs and wings, and they no longer have to chase birds on the floor. The amount of dust is lessened, too.

O.K. Industries’ McDaniel said the “hanger” job is the hardest position in the plant to staff. Not many people want to fight a 6-pound chicken, he said.

But since adopting atmospheric stunning, the plant’s hanging crew “has been fully staffed for the last three months,” McDaniel said adding that with live birds it was common to replace two hangers a week.

The National Chicken Council, an industry trade group in Washington, D.C., said the industry is paying attention to what O.K. Industries is doing, and “we can’t rule out that it might catch on,” spokesman Richard Lobb said.

Business, Pages 65 on 07/03/2011