Ventilation shutdown plus heat is considered the most “cruellest option” for killing birds affected by the continuing bird flu epidemic.

Just like humans and animals, birds have their own pandemics. This year, the H5N1 virus, or bird flu, has affected millions of birds in factory farms like chickens, ducks, and turkeys.

Since early 2022, more than 49 million birds in 46 US states have been impacted by the virus.

The UK and Europe are also coping with an “unprecedented” number of cases of the infection in their farmed birds as well as their wildlife. Between June to September, there were five times the amount of outbreaks than in the same duration last year.

Culling methods

While many of the infected birds succumb to the H5N1 virus, millions more are killed deliberately, en-masse to contain the spread of the virus.

 According to a report by Animal Welfare Institute (AWI) based on USDA data, farmers use three main ways to kill large flocks.

These include suffocating the birds by filling barns with CO2, choking the birds by filling barns with foam and ventilation shutdown plus heat (VSD+). 

Of those 3 methods, VSD+ is the cheapest and most common technique. But it’s also the one that causes the birds the most suffering. 

It involves cutting off airflow in a barn, followed by raising temperatures of the barn to 104 degrees Fahrenheit. This causes the site to essentially become a giant oven, and the birds die by suffocating or overheating, often after suffering for hours. 

Animal advocates describe the process as “basically cooking animals alive”. Even vets deem this technique as ‘the most inhumane method available’.

European officials have also flagged VSD+ as “likely to be highly painful” and “must never be used”. 

However, the AWI analysis found that US farmers chose to use VSD+ in 73% of the culls carried out over the past few months.

Moreover, the National Association of State Departments of Agriculture (Nasda), which represents state-level agriculture agencies across the US, has approved a measure asking the US Department of Agriculture (USDA) to consider making it a “preferred” method, the Guardian reports.

This would mean that US farmers can bypass the other two currently preferred methods and opt for VSD+ without seeking approval or permission.

Dena Jones is the director of the Animal Welfare Institute’s farm animal programme. She said: “Although the avian flu outbreak is global, only the US has put ethics completely aside and intentionally induced heatstroke to kill millions of animals.”

She added: “In the current outbreak, [VSD+]—once considered an option of last resort—has become the default,”

Nasda in a statement said: “Nasda does not endorse single methods of depopulation, rather Nasda supports considering the uniqueness of each region, state and farm when making decisions regarding depopulation and recommends using methods that minimise the loss of life to animals.” 

Avian flu’s growing threat

The avian flu outbreak in 2014-2015 resulted in the death of 50 million chickens and turkeys and cost taxpayers approximately $850 million.

Meanwhile, the current outbreak, which is concentrated in a handful of states, has already spread to chicken and turkey flocks nationwide.

In the last five months, the USDA’s Animal and Plant Health Inspection Service (APHIS) has found the flu in 184 commercial flocks and 176 backyard flocks.

Wild birds have also been affected by the virus.

“Even mild strains of animal viruses can have a catastrophic impact,” Jones explained.

Viruses mutate quickly on factory farms. The lack of genetic diversity also makes it very easy for the virus to infect entire flocks.

While bird flu is normally expected to die down in summer months, this hasn’t happened, either in North America or Europe.

Virus impact on humans

Aside from infecting birds, the virus also puts workers at risk of contracting the disease and spreading it to surrounding communities.

So far, the bird flu virus hasn’t been very successful in spreading among humans. Since 2003, only 865 humans have been infected. However, over half of those cases were deadly.

Furthermore, history has shown that these viruses have the potential to mutate and become more contagious between people.

• Read: England must eat at least 30% less meat to avoid climate breakdown, says food tsar

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