US Agriculture officials recently approved new method to kill poultry infected by bird. The officials said under the new method, the infected poultry will be killed by turning up the heat and shutting off ventilation systems.

The US Department of Agriculture (USDA) said in a statement that it will consider this method only if there are no other ways to kill flocks within 24 hours of infections being detected.

According to the agency, they want that the infected poultry should be killed within a day to prevent the virus from spreading to other parts. Almost 50 million chickens and turkeys died from bird flu or were culled from December through June in the country's worst animal disease outbreak on record.

The Humane Society of the United States said shutting down the ventilation system will bake the birds to death. "We shouldn't compound the problems for birds by subjecting them to a particularly miserable and protracted means of euthanasia", said Michael Blackwell, Humane Society's chief veterinary officer.

The Agriculture Department said in a statement that the method according to them is very necessary alternative because of the need to eradicate the virus as soon as possible to prevent further spread.

According to the agency, its first choices for culling infected poultry will be suffocating them with foam or in chambers filled with carbon dioxide. It has been two months since the last infection. But still officials are preparing for a potential reappearance of the flu this fall because wild ducks, which can carry the virus, will be migrating.