U.S. agriculture officials seeking to control deadly bird flu have approved a method of killing infected poultry that entails sealing barns shut, turning up the heat and shutting off ventilation systems, an option that has been condemned by animal rights groups as cruel.
The Agriculture Department (USDA) said in a statement that it would consider using the method if there are no other ways to kill flocks within 24 hours of infections being detected.
The agency wants to cull infected flocks within a day to prevent the virus from spreading. Nearly 50 millions chickens and turkeys died from bird flu or were culled from December through June in the country's worst animal disease outbreak on record.
Shutting down ventilation systems in poultry houses "essentially bakes the birds to death," the Humane Society of the United States said.
“We shouldn’t compound the problems for birds by subjecting them to a particularly miserable and protracted means of euthanasia," said Michael Blackwell, the Humane Society's chief veterinary officer.
The Agriculture Department said the method was a "necessary alternative" because of the need to eradicate the virus.
According to the agency, its first choices for culling infected poultry will be suffocating them with foam or in chambers filled with carbon dioxide, methods widely used last spring.
More than two months have passed since the last infection. However, officials are preparing for a potential resurgence this fall because wild ducks, which can carry the virus, will be migrating.
It takes about 30 to 40 minutes for birds to die from heat stress during the process, known as ventilation shutdown, said T.J. Myers, the Agriculture Department's associate deputy administrator for veterinary services. He said the agency had never used the method.
"We certainly hope we don't have to use this, or any depopulation methods," Myers said.
The government is trying to improve its response after farmers complained the agency had moved too slowly in killing and disposing of infected flocks. Delays can contribute to the spread of the disease.
Separately, the Agriculture Department has allowed Harrisvaccines to become the first company to produce a vaccine to fight bird flu. The agency plans to build a stockpile of vaccines in case there is another outbreak. It has not given any company permission to market a vaccine.
"Really the only buyer right now would be the U.S. government," Harrisvaccines spokesman Joel Harris said.