Background 6526 views 1 commentupdate:Mar 9, 2016

Gas foam: The humane euthanasia method

On farm euthanising or slaughtering of poultry or pigs with the use of nitrogen foam may be the way to go in the future. An abundance of nitrogen, captured in foam bubbles, ensures a stress free death in a short period of time.

By Fabian Brockotter

The total absence of oxygen, is the main principle of the N2GF technology. However, that is not what makes this technology unique, existing stunning methods with carbon dioxide and carbon dioxide plus argon gas, do exactly the same. The big difference is in the actual 'medical cause' of death of the animal. With the use of carbon dioxide the animal perishes due to hypoxia, but with the use of nitrogen, death is through anoxia. Unlike hypoxia, the animals do not react by head shaking or having convulsions prior to unconsciousness. In fact, the animals do not even notice they are dying.

The initial investment and operating costs are very low for the farm. The equipment necessary at farm level are; a pressure tank of nitrogen or a nitrogen generator, a pressure vessel for water and soap mix and a foam nozzle.

Method of use
A standard barrel, sufficient in size to take the animal in question, is filled with a layer of high expansion foam (big bubbles) filled completely with pure nitrogen. The animal is then immersed into the foam and covered with a layer of foam of at least 60 cm. The animal then breathes in 98% 
nitrogen, the blood oxygen diminishes very quickly and the animal loses 

Because of the extreme oxygen deficiency (anoxia) the animal dies within 1.5-2 minutes and at no time regains consciousness. Due to the fact that an animal generally inhales air that is 80% nitrogen they do not notice the extra 18%. And because they do not realise they are dying they do not fight the procedure, thus experience no stress or pain. Unlike with high concentrations of carbon dioxide, then the animal tries to breathe. The chance that the method fails and the animal regains consciousness and does not die, is virtually zero.

Usability and safety
Using nitrogen foam also places no physical demands on the farmer or his employees. The animal is almost instantly unconscious after being dipped into the foam. In addition restraining of the animal, to avoid them hurting themselves as with stunning, is also not necessary.

To be sure that the nitrogen doesn't escape during the procedure there will always be a layer of 60 cm of foam above the animal. Plus the thick layer of foam prevents the nitrogen from escaping, making it safe for the operator.

The advantage of the high expansion foam is that the nitrogen gas is captured in the bubbles. Nitrogen is lighter than the surrounding air and would normally mix quickly with ambient air. After a longer period the foam disappears and the nitrogen mixes with the surrounding air, without any risks. Working with nitrogen gas foam is also hygienic. The animals will stay in the barrel were they are euthanised. No body fluids escape.

Swine Research Centre of Wageningen University, the Netherlands, began extensive research on the use of 
nitrogen foam in January this year. The purpose of the research is to prove that the animals are unconscious in a short time and die due to lack of oxygen. Also to be tested is that the animals do not suffer from stress or pain during the procedure. An exploratory survey with poultry already showed that this is achievable. Before scaling up to plant level, project N2GF (nitrogen 2 gas foam) is focusing on farm level and testing this novel method extensively.

Next to the effects on the animals the reliability of the equipment will also be tested, and a standard operating procedure will be developed. 
Possible risks for the operators or the environment will be examined. Testing on the equipment is expected to be completed in six months. At which time it will become available commercially. For the operators, training will be an integral part of this new method.

Anoxia caused by Nitrogen Foam: An alternative for stunning animals with high concentrations of CO2?
In the International Journal of Pharmacology, a group of Mexican scientists discuss the controversies related to stunning pigs and poultry with high concentrations of CO2. One of the recommendations were: ‘From the perspective of animal welfare, 90% argon, or the lowest possible CO2 concentration to stun a pig is recommended. Argon is suggested as a welfare-friendly alternative to carbon dioxide for stunning/killing pigs and poultry’.
During this research, 90% Argon in combination with CO2 was reviewed: a combination of gasses resulted in being the same as using Nitrogen foam, filled with 98% nitrogen: Anoxia, the total absence of oxygen. Is it fair to suggest that Anoxic Nitrogen Foam would be a reasonable alternative for using high concentrations of CO2?

World Poultry

One comment

  • M H W van den bos

    Anoxiatec, an Australian private company has already developed applications for the euthanasia of farm animals with the N2 gas filled foam.
    A small installation comprising of a N2 generator and a foam producing nozzle with a container to hold the animals is available.
    please visit for details.

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