Amid Bird Flu Outbreak, Meat Producers Seek “Ventilation Shutdown” for Mass Chicken Killing

A hen, hooked up to electrodes, stands alone in a glass cage. She starts panting, thrashing, slumping over, and lunging at the enclosure’s walls, appearing to look for an escape. Outside the cage, researchers point, take notes, and watch her die.

These scenes, which took place at North Carolina State University, were documented in 10 hours of video footage recently obtained via public records requests by the organization Animal Outlook and shared with The Intercept. The experiments were funded by the U.S. Poultry and Egg Association, a major industry trade group, and took place in the wake of the 2015 outbreak of an aggressive bird flu that resulted in the culling of about 50 million farmed birds — not all of them necessarily infected — across the United States. The researchers were testing what was then a relatively new set of disease control methods: known as “ventilation shutdown,” the process kills the animals through heatstroke and suffocation, similar to dying in a hot car. According to Will Lowrey, the Animal Outlook attorney who obtained the videos, “the suffering is extremely profound.”

In 2020, Iowa Select Farms, the state’s largest pork producer, killed healthy pigs, who could not be slaughtered for food due to Covid-induced slaughterhouse closures, by sealing off the airways and pumping in heat: a practice called “ventilation shutdown plus.” In a groundbreaking undercover investigation covered by The Intercept, the animal rights group Direct Action Everywhere revealed pigs screaming in distress for hours as they, essentially, roasted to death. Soon after, Iowa Select announced that it was discontinuing its use of the method, commonly abbreviated as VSD+. New documents obtained through federal and state public records requests reveal that, far from being an aberration, the meat industry’s use of this gruesome method is still on the rise — and it’s being abetted by government and organized veterinary medicine.

Now, another strain of highly pathogenic avian influenza, or HPAI, is tearing through the country. More than 27 million chickens, turkeys, and other birds have been killed or scheduled to be killed — or “depopulated,” in meat industry jargon — since February. Many of these animals were killed with ventilation shutdown plus. In Iowa, the nation’s top egg-producing state, 5.3 million hens at a Rembrandt Enterprises egg factory farm were exterminated with VSD+ last month, the Storm Lake Times reported. (Asked to confirm this report, Chloe Carson, communications director for Iowa’s agriculture department, told The Intercept that she could not disclose the method and denied specifying it to the newspaper, though the story says she confirmed it was the method used. Tom Cullen, the story’s author, said he stands by his reporting and that he’d spoken to local personnel and former company employees with knowledge of the method. When contacted by The Intercept, Sheila Hagen, Rembrandt’s vice president of HR and legal, immediately hung up.)

Ventilation shutdown plus was also used in February at two chicken and turkey facilities in Kentucky, according to records from the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service, or APHIS, which oversees management of farm animal disease outbreaks. In Minnesota, more than 1.7 million birds, mostly turkeys, have been or will soon be depopulated since the state’s first avian flu case on March 25, with an increasing number killed using VSD+ compared to the 2015 bird flu, according to state veterinarian Beth Thompson. In public records first released to Lowrey, requests to use the method have also appeared in Wisconsin and Missouri. The USDA financially compensates meat producers for these killings.

The videos obtained from NC State are remarkable because the meat industry often claims that undercover footage of cruel conditions taken by activists is doctored or staged. But these videos came directly from an industry-funded study, the raw footage of which was shared with The Intercept.

The research tested multiple versions of VSD: ventilation shutdown alone, which entails sealing off airflow to the birds’ cages, causing their body temperatures to rise to lethal levels; ventilation shutdown with additional heat, which speeds the process of killing them via heatstroke; and ventilation shutdown with carbon dioxide, which deprives the chickens’ bodies of oxygen. VSD with the addition of either or both of these is referred to as “VSD+.”

The hens took more than 91 minutes to die from ventilation shutdown alone, 54 minutes to die from VSD with supplemental heat, and 11.5 minutes to die from VSD with carbon dioxide, according to a 2017 final report based on the research that was submitted to the U.S. Poultry and Egg Association. According to a separate study published the following year by some of the same researchers, time to death is significantly longer for hens in a large, multilevel cage setting, which more closely resembles factory farm conditions than individual cages: 3.75 hours for VSD alone, 2 hours for VSD plus heat, and 1.5 hours for VSD plus carbon dioxide.

In some news reports on the current avian flu, sources have said that exterminating birds is more humane than letting them die of the disease. And HPAI is undoubtedly a terrible illness. “Many birds die suddenly, with mortality rates as high as 100% within a few days, though it can also take weeks. The dying birds likely suffer enormously as they struggle to breathe, develop diarrhea, and become paralyzed or otherwise neurologically compromised,” Gwendolen Reyes-Illg, a veterinary adviser to the Animal Welfare Institute, told The Intercept in an email.

In their 2015 funding proposal — asking the U.S. Poultry and Egg Association for $110,075 to support the experiments — the NC State researchers wrote, “The objective is to examine the humane aspects and effectiveness of ventilation shut down (VSD) for depopulating laying hens in cage systems,” but “humane” is not defined in the proposal. “However unpleasant, it should be a primary goal that depopulation (euthanasia) methods strive to meet these standards within the context of the extreme need scale in which VSD would be used.”

Other common methods of killing poultry birds — carbon dioxide poisoning and suffocation with firefighting foam — are not as effective on birds used in egg production as on those in meat production, the proposal says. Egg-laying hens in factory farms are typically kept in cramped, vertically stacked battery cages, while chickens raised for meat are packed together on the floor.

Although the test conditions shown in the footage — individual hens killed inside plexiglass cubes — aren’t the same environment as a factory farm, the videos suggest the degree of panic and suffering birds experience when they’re killed with VSD.

“These are birds in extreme distress,” said Sherstin Rosenberg, a veterinarian who has cared for thousands of chickens and other poultry birds at an animal sanctuary in California, after reviewing the NC State footage. “They are literally fighting for their lives, they’re gasping for air, they’re struggling.” The videos don’t have any audio, but Rosenberg added: “These birds look like they’re vocalizing to me. I think they were probably crying out.”

In the global scientific community, she said, “it’s generally accepted that, if one could assume that a procedure would cause pain or distress to a human, you can also assume it would do the same for an animal.”

Birds used in agricultural research get no protection under federal welfare laws. “The Animal Welfare Act, in the very definition of animals, excludes a number of types of animals used in laboratory experiments. These animals include rats, mice, and birds bred for research, as well as agricultural animals used for agricultural research,” said Jeremy Beckham, research advocacy coordinator for the Physicians Committee for Responsible Medicine. The agricultural exemption, he added, is “specifically [because] there are things done commonly to animals in an agricultural context that would be violations of the law if they were done to other research animals.”

The names of the researchers were redacted from public records obtained by Animal Outlook. But the 2017 final report lists the lead investigator as Kenneth Anderson, a professor in NC State’s Prestage Department of Poultry Science. Listed as co-investigators were professors Kimberly Livingston, Sanjay Shah, and Mike Martin, who is now North Carolina’s state veterinarian. Wallace Berry of Auburn University is listed as a collaborator. At NC State, the Prestage Department of Poultry Science advertises its “strong industry ties” and is named for the Prestage family, the owners of Prestage Farms, a poultry and pork company headquartered in North Carolina.

“If you keep a house full of infected birds, and the pathogens spread through the ventilation air, soon you have many more farms infected. So rapid depopulation is vital,” Shah wrote in an email to The Intercept. “If you just turn off the ventilation system and seal the house, it takes longer for the birds to die than if you provided heat to speed up the process. Of course, CO2 would be faster but we might have supply issues in the event of a large scale outbreak. While the depopulation methods we investigated are not painless, neither are poultry diseases such as avian influenza that has recently infected many farms in NC. Chickens infected with respiratory diseases such as avian influenza also suffer shortness of breath and other painful symptoms and the suffering continues to happen for several days until death occurs. I wish there were less painful options.”

An employee in Martin’s office suggested contacting “the university” about the study, adding that “in North Carolina we are using the foaming method to depopulate infected flocks for High Path Avian Influenza.” Livingston was unreachable, and neither Anderson nor Berry responded to The Intercept’s requests for comment, nor did NC State’s Institutional Animal Care and Use Committee, which approved the research.

Thanks in part to the NC State researchers’ work, the use of ventilation shutdown at U.S. factory farms is increasing in several states. The American Veterinary Medical Association’s depopulation guidelines cite NC State’s research when listing VSD+ as a kill method “permitted in constrained circumstances.” The guidelines note that “a humane approach to the depopulation of animals is warranted, justifiable, and expected by society, but may not be actualized in some cases.” They don’t claim that VSD+ is humane but instead view it as a last resort.

In email correspondence from March obtained by Lowrey in a public records request, Tyson Foods requested and received permission from the Missouri state veterinarian to depopulate a chicken facility with VSD+.

USDA records show that only one HPAI outbreak has been reported in Stoddard County, Missouri, so far this year. It was detected on the day before the email from Tyson was sent, making it almost certain that the nearly 300,000-bird facility was owned by the meat industry giant. In an email to Lowrey, USDA spokesperson Lyndsay Cole confirmed these chickens were killed with a combination of foam (a method that suffocates birds under a blanket of foam) and VSD.

In another email, pertaining to another one of the country’s largest depopulations so far — 2.7 million hens at Cold Spring Egg Farm in Jefferson County, Wisconsin — an APHIS veterinarian asked, “Are we starting VSD+ tomorrow?” Neither Tyson nor Cold Spring Egg Farm responded to The Intercept’s requests for comment.

The vast majority of depopulated birds haven’t tested positive for HPAI. If the virus is detected in even one bird, all the birds in the flock must be killed, even if they live in separate sheds. But the decision to resort to cruel cull methods like VSD+ is a crisis of the meat industry’s making.

“The tragedy here is that our current methods of raising birds for food production, in enormous sheds with millions of stressed, nearly genetically identical birds in close proximity to one another, has resulted in a situation where outbreaks of diseases like HPAI are nearly inevitable and few options exist for humanely killing infected birds,” Reyes-Illg, the Animal Welfare Institute veterinary adviser, wrote to The Intercept. “Killing methods that are more humane than killing via heatstroke require planning and preparation, and some … require more research to be commercially viable, and none of this seems to be a priority for the industry.”

By one count, more than 1,500 U.S. veterinarians, including Reyes-Illg, have urged the American Veterinary Medical Association to reclassify VSD+ as not recommended. AVMA guidelines themselves aren’t legally binding, but they often become the basis for policy. APHIS’s policy on managing bird flu, which draws from the AVMA’s guidelines, states that VSD+ should only be used if other methods — foam or carbon dioxide — won’t be available in time. Foaming is “cruel but not as bad as VSD+,” Reyes-Illg said.

As long as animals are mass produced for food, there will be a need to cull animals in emergencies, and companies have an obligation to prepare for that scenario by having supplies on hand to do it in the least cruel way possible, said Peter Sandøe, a bioethicist at the University of Copenhagen. “Not to embark on such preparations in light of what happened recently” — during the mass exterminations of healthy farm animals due to Covid-19 — “is a sign of a dreadful cynicism and lack of compassion on the side of the industry,” Sandøe added in an email. In the European Union, neither VSD nor firefighting foam are considered acceptable kill methods.

USDA records indicate that VSD was used to kill birds at four facilities in Indiana in 2016, before the NC State research was published. But the NC State report is the only scientific research cited in the AVMA guidelines on ventilation shutdown in birds, though other studies have since been published on the method in birds and pigs.

“I think the AVMA looked to [the NC State] studies and others as some aspect of legitimacy. To say, ‘Yes, this is doable, it’s not that bad,’” said Lowrey, the Animal Outlook attorney. A 2021 letter from the Animal Welfare Institute to the AVMA criticizes the NC State report on numerous scientific grounds and states that it “was so poorly written and/or edited that it was difficult at times to discern what the author was attempting to communicate.” The study uses something called “heat shock protein 70” as a measure of stress in the hens, which both the Animal Welfare Institute and Sherstin Rosenberg said is not a legitimate measure of the animals’ welfare. The funding proposal said the researchers planned to measure corticosterone, a more accepted measure of stress, but the final report makes no mention of it.

“State animal health officials and producers carefully weigh the different options to determine the best option for humane depopulation and do not make such decisions lightly,” USDA spokesperson Mike Stepien told The Intercept in an email. “Ventilation shutdown plus heat or CO2 (VSD+) is at times the only method available to meet the 24–48-hour goal to depopulate the birds and end their suffering from the disease.”

But if a company can perform VSD plus carbon dioxide, then presumably they have access to carbon dioxide and can kill their birds with CO2 gassing alone — a method Reyes-Illg called “relatively humane” compared to VSD. Stepien explained that “ventilation shutdown plus (VSD+) heat is the only VSD+ that has been used in the United States. VSD+ CO2 is theoretical and not yet practical.”

As cruel as VSD is in controlled lab experiments like NC State’s, there is evidence that its real-world implementation on factory farms is botched, resulting in animals being thrown away alive. In undercover video footage of the depopulation at Rembrandt Enterprises (as identified by activists and confirmed by The Intercept with images from Google Maps and Rembrandt’s website) last month, Direct Action Everywhere documented dead hens being moved by conveyor belts into dump trucks. But numerous hens caught on film were still alive and left behind inside the battery cage facility, and one was still alive and standing outside after being dumped.

Rosenberg said it’s easy to mistake live animals who have been unsuccessfully killed in depopulation for dead. “Based on the large number of birds who are alive, healthy, and alert in the footage, it is a certainty that many more who appeared dead were buried alive,” she wrote in a professional opinion after reviewing Direct Action Everywhere’s videos. With millions of hens hastily exterminated at the facility, even a small proportion of them unsuccessfully killed could result in thousands dumped alive.

This is at odds with the AVMA’s standards, which state that VSD+ is permitted in “constrained circumstances” only when “applied in a manner that will produce a 100% mortality rate.”

Whatever the kill method used, factory farm conditions make it exceedingly difficult to carry out depopulations with full mortality, Rosenberg said. “We can quibble about degrees of suffering,” she said. “But in the end, they’re all just terrible methods of killing.”