Why 6.5 million chickens were killed in Michigan this month

For two years, Michigan largely dodged a deadly bird flu.

By the end of last year, the highly pathogenic avian influenza had infected a couple dozen backyard flocks and was detected three times at turkey farms. But in the past month, the death toll of Michigan birds has skyrocketed, and dairy cows are starting to get sick.

A recent infection in Ionia County dealt the biggest blow: nearly 6.5 million dead chickens.

“Obviously when you get an outbreak of a disease like this, it raises a lot of questions and we’re taking it very, very seriously,” said Michigan Department of Agriculture and Rural Development Director Tim Boring.

This strain of the avian flu, H5N1, started spreading in the United States after it was first detected in two South Carolina wild ducks in January 2022. Since then, it’s become the deadliest bird flu in history, affecting more than 90 million birds.

It’s so contagious that farms with even one infected bird are required by the U.S. Department of Agriculture to depopulate, or kill, their entire flock. But many commercial farms, including in Michigan, have been relying on what critics call an inhumane method to kill their flocks that prolongs animal suffering.

Avian flu tears through egg farms

Herbruck’s Poultry Ranch faced its worst-case scenario at the end of March.

A farmworker at Herbruck’s, the biggest egg producer in the state that supplies eggs to every McDonald’s restaurant east of the Mississippi, noticed sick birds at the farm’s Ionia County organic facility. Testing confirmed their fears.

“Herbruck’s is heartbroken by the loss of any hen, and we were devastated to learn that some of the hens at our Green Meadow Organics facility are infected with highly pathogenic avian influenza,” CEO Greg Herbruck said in a statement earlier this month.

The fourth-generation family farm, which has 10 million egg-laying hens across three states, did not confirm how many birds were impacted. But federal data shows almost 6.5 million chickens at Ionia County egg farms were depopulated between April 3 and April 16 – making it one of the biggest cullings in the country.

Related: Avian flu strikes Michigan’s largest egg producer

Michigan now ranks fifth for avian flu-related deaths behind Iowa, Ohio, California and Nebraska.

“Over the course of the last two years, as we’ve seen this outbreak spread across the country, nearly every state has been affected. And many states have had some of the large commercial detections like we’ve had most recently,” said Kim Dodd, director of Michigan State University’s Veterinary Diagnostic Laboratory, which does avian flu testing.

It’s hit egg producers particularly hard.

Egg farms have depopulated 63 million birds with the 39 largest mass killings in the country, federal data shows. That includes two producers in Iowa that each killed 5 million birds in spring 2022. And Cal-Maine Foods, the largest egg producer, idled a Texas facility earlier this month after depopulating 1.6 million birds, about 3.6% of its total flock.

Outbreaks like these drove egg prices to record highs last year, hitting an average of nearly $5 a dozen.

Herbruck says his egg farm has been working “around the clock” to follow federal protocols and disinfect facilities before production can start again. The company plans to lean on its unaffected farms and a supplier network to keep distributing eggs.

To compensate losses, the USDA pays farms for birds and eggs that need to be destroyed because of the flu. As of January, more than $1 billion had reportedly been spent on these indemnity payments.

“You’re looking at a commercial operation that is forced with depopulating the entire flock, and it’s a significant economic hit,” Boring said.

Health officials emphasize no eggs from infected animals will enter the food supply and the flu carries a low risk for humans – only two people who had contact with farm animals have gotten sick.

How are birds depopulated?

Depopulation is the main tool used to contain an infection.

Affected farms need to act quickly because the flu is particularly vicious for chickens and turkeys. It can rapidly multiply and infect every bird in a single day. Sickened birds will then struggle to breathe, gasping for air, suffering from extreme diarrhea and likely dying within two days.

“I think it’s important to remember that our domestic poultry get very sick with this infection,” Dodd said. “So, in this case, we are not stamping out the infection just to eliminate the virus. It’s also a welfare issue.”

Related: A chicken started gasping for air. Three days later, more than 60 birds were dead.

After the last outbreak of highly pathogenic avian influenza in 2015, the USDA determined “one of the most critical problems” was how long it took to kill an infected flock. Methods like water-based foam or carbon dioxide gassing can require outside contractors and supplies.

This gave the virus, which spreads easily though farm equipment, clothing and even dust particles, more opportunity to circulate. With speed a priority, the USDA set a goal of depopulating birds within 24 to 48 hours by allowing farms to use a method called “ventilation shutdown plus.” Research shows this process takes around 2 hours.

“A depopulation delay creates a serious biosecurity challenge for responders, who must consider sick birds, their feces, and everything in contact with those materials as infectious,” the federal agency says in its ventilation shutdown plus policy.

This method involves sealing vents, pumping heat into barns and raising the temperature to between 104 and 110 degrees until the animals have died from hyperthermia. In some cases, carbon dioxide is also used.

The American Veterinary Medical Association, which developed the depopulation guidelines, advises this should only be used in “constrained circumstances” when other methods are not available or the virus “poses a significant threat” of further spread.

But analysis from the Animal Welfare Institute, an advocacy organization, found that over 81% of avian flu depopulations used ventilation shutdown plus through December 2023. It was also used to kill pigs when slaughterhouses were shuttered during the COVID-19 pandemic.

“Unfortunately, it’s really become entrenched and a standard method,” said Gwendolen Reyes-Illg, a veterinary medicine consultant for the Animal Welfare Institute’s farm animal program.

Related: Bird flu spreads to 3 more Michigan commercial dairy farms

More than 2,000 veterinarians have signed a letter urging companies to use “less cruel” methods. And the Animal Welfare Institute has petitioned the USDA to make indemnity payments contingent on farms having “a plan for humanely depopulating animals.”

In Michigan, though, commercial farms have leaned on ventilation shutdown plus.

The three infected Muskegon County turkey farms used it, according to records obtained from Our Honor, an animal advocacy organization. And the USDA confirmed the millions of chickens depopulated in Ionia County died from ventilation shutdown plus.

The USDA understands the concerns from animal rights advocates, spokesperson Shilo Wier said in an email, but ventilation shutdown can be “more effective and humane” than a process that takes longer because birds will also endure agonizing flu symptoms.

“Ultimately, the producer may make the difficult decision to shut off the ventilation fans and heat the buildings in the operation to depopulate the birds quickly and end their suffering from the disease,” Weir said.

Avian influenza still spreading

After two years and millions of dead birds, avian flu is not slowing down.

At the end of March, the flu was detected for the first time in a herd of Texas dairy cattle – a surprise to scientists. Thousands of dead sea elephants lined an Argentinian beach after a large outbreak last fall. And it’s continued to sicken wild birds and mammals.

“We see that the high path avian influenza strain kind of goes away when we hit winter,” Dodd said. “But we’ve had fairly mild winters and so we’ve continued to see it circulating across the country.”

This worries Reyes-Illg.

“I think that if we really were serious about wanting to rein in avian influenza, we would be looking at some of these big picture issues: vaccination, farm size, farm density and the conditions on the farm that make animals more at risk of infection and of infection spreading rapidly,” she said.

To address the ongoing threat, the USDA started vaccine trials for several flu strains last year.

But significant challenges remain in developing, approving and deploying a vaccine for domestic birds. For one, vaccinated birds might not get as sick, but they could still spread the virus. There are also trade restrictions on vaccinated poultry being imported or exported between countries.

Related: A deadly bird flu raised egg prices. Michigan farms vigilantly protect flocks.

For now, biosecurity remains king: keeping flocks away from wild birds, limiting visitors and disinfecting clothes, shoes, vehicles and farm equipment. The USDA calls it an “every day, every time” approach.

“Our priority is really trying to ensure that we minimize interaction between wild birds and our domestic poultry flocks, including our backyard flocks as well,” Dodd said.

Michigan poultry farms have been on high alert for over two years, deploying strict biosecurity measures like requiring workers to wear protective Tyvek suits, replacing dirt with concrete and fogging trucks with disinfectant. Boring says this hypervigilance is why Michigan had not seen a major outbreak until recent weeks.

“This is a cautionary tale of ensuring that all those biosecurity practices remain in place and at the highest level,” he said.