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This footage shows the gruesome foam suffocation method being used to kill chickens infected with bird flu .

The video shows a barn filled with thousands of birds flapping and jumping around as litres of white foam is poured on top of them.

The chickens can be seen desperately scrambling over each other as the froth creeps closer but the tight confines of the pen means they have nowhere to go.

The technique is said to obstruct the birds' upper respiratory tract, including the trachea, suffocating them to death.

It should “result in the death of 95% of birds within seven minutes and 100% of the flock within 15 minutes of submergence," according to United Poultry Concerns (UPC).

UPC reports that the US Department of Agriculture’s Animal and Plant Health Inspection Service approved using the method in cases of outbreaks of disease in November 2006.

The Washington Post reports that the only approved method of euthanasia for egg-laying hens is by exposure to carbon dioxide gas, which puts the birds to sleep before killing them.

The method most commonly used for turkeys and broiler chickens involves the use of a water-based foam, which kills the birds within approximately one minute, the newspaper claims.

The above footage was said to have been filmed in Israel in 2014, where the practice is said to also be an acceptable practice of mass extermination of infected birds.