Comparing firefighting foam and 100% Co2 for depopulating poultry

Current control strategies for avian influenza (AI) and other highly contagious poultry diseases include surveillance, quarantine, depopulation, disposal, and decontamination. Selection of the best method of emergency mass depopulation needs to maximize human health and safety while minimizing disease spread and animal welfare concerns. An overall goal of this project was to find a way to evaluate the welfare of the poultry subjected to a depopulation treatment. This study consisted of two experiments to evaluate the efficacy of mass depopulation methods. Experiment 1 was conducted as a proof of concept for the use of the alpha/delta (A/D) ratio in evaluating the time to loss of consciousness in poultry. Experiment 2 was conducted to evaluate the effectiveness of two mass depopulation methods on turkeys. The methods that were tested were carbon dioxide (CO2) gassing and firefighting foam.

Not that, according to Directive EU 1099/2009 firefighting foam is not allowed to be used for culling poultry within the European Union.

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Research shows nitrogen more practical than carbon dioxide for euthanizing pigs

December 12, 2012, Manitoba Agriculture News.

Research conducted by the University of Manitoba has shown nitrogen to be a more practical alternative for mass euthanasia of swine than carbon dioxide.

The University of Manitoba in partnership with the Canadian Swine Health Board, Manitoba Pork Council and Manitoba Agriculture Food and Rural Initiatives is developing a mobile mass euthanasia system for swine and poultry.

Phase one of the project, which started about a year ago, was to design and test a pilot system and phase two is to design a full sized system.

Dr. Qiang Zhang, a professor in Biosystems Engineering with the University of Manitoba, says the pilot system has been tested, it worked well and the next step, once funding has been secured, will be to develop the full size system.

The current method of euthanasia is CO2.

If you actually use CO2 basically you have to truck in CO2 in bottles from elsewhere to take it to the site, say on a farm.

Our system actually uses nitrogen, basically uses pure nitrogen to reduce the oxygen to two percent or lower level so that should actually euthanize any animal.

The reason why we’re using nitrogen is because, first nitrogen is abundant in the air.

We actually will be looking at an on-site nitrogen generation system to produce our own nitrogen right on the spot.

The advantage of that is if you have a large outbreak of disease and if you use the current method of CO2 then there’s simply not enough CO2 supply actually in the province.

Nitrogen, you’re facing the same problem,

Where do you get the large quantity of nitrogen.

Our system actually will avoid that problem by generating our own nitrogen on site.

Dr. Zhang says, when using carbon dioxide for euthanasia was to compared to using nitrogen, nitrogen scored much better than carbon dioxide from an animal welfare perspective but in terms of public perception the two were pretty much equal.

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Using Nitrogen for Euthanasia Improves Welfare

January 8, 2013, The Poultry site, News: CANADA – Research conducted by the University of Manitoba has shown, from an animal welfare perspective, nitrogen is a better alternative for mass euthanasia than carbon dioxide, writes Bruce Cochrane.

Dr Qiang Zhang, a professor in Biosystems Engineering with the University of Manitoba, describes in a radio interview with Farmscape online that the current emergency response systems use carbon dioxide where as the new system uses nitrogen:

‘We actually compared CO2 with our new system. We were looking at the two aspects, one is the animal welfare, the other one is the public perception. Animal welfare is strictly looking from the animal’s point of view.

We actually use video tape to observe the behavior of the animals and with a panel of experts we actually score the welfare behavior.

Also we did the same thing with the public perception. In quick summary, the nitrogen actually scored much better than the CO2 in terms of animal welfare but from the public perception point of view the two were pretty much equal.’

Listen to the entire radio interview:

Read the article of January 8, 2013 in the Poultry site:

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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 of high concentrations of Co2.

One of the recommendations was: ‘From the perspective of animal welfare, 90% argon by volume, or the lowest possible Co2 concentration to stun a swine is recommended. Argon is suggested as welfare-friendly alternative to carbon dioxide for stunning/killing pigs and poultry’.

During this research, 90% Argon in volume in combination with Co2 was reviewed: a combination of gasses resulting to 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?

Read the entire report:

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Report McKeegan: High expansion foam; a humane way of killing? (Oct. 2011)

Dorothy McKeegan presented on October 2011 her study: High Expansion Gas-foam: a humane agent for emergency killing of poultry? Dorothy studied Zoology at the University of Glasgow before completing the MSc in Applied Animal Behaviour and Animal Welfare at Edinburgh University.

After gaining her PhD in 1999, she worked at Roslin Institute near Edinburgh, conducting neurophysiological and behavioural research relating to the welfare of poultry. Dorothy was appointed as the BVA Animal Welfare Foundation lecturer at Glasgow in February 2005, and her teaching role involves delivering an integrated teaching programme for animal welfare and ethics across the undergraduate curriculum.

As a member of the Division of Animal Production and Public Health, Dorothy continues to pursue her research interests in avian sensory physiology, pain perception and poultry welfare. In current projects she is investigating avian pain, humane emergency slaughter and the welfare implications of production-related conditions. Dorothy also has an educational research interest in the teaching and assessment of ethical reasoning in veterinary students.

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Report Marien Gerritzen: Welfare assessment of gas filled foam for killing poultry (2010)


During outbreaks of notifiable diseases in poultry control measures require poultry to be killed on-farm, preferably in their production housing in order to reduce the risk of spreading the disease.
The Dutch governments interest in the potential of delivering gas into sheds using high- expansion foam as an acceptable method of emergency killing of poultry is shared by the UK government (Defra). To maximise the benefits of complementary research a collaborative programme of research between the respective project leaders Dr Dorothy McKeegan and Dr Marien Gerritzen

(Livestock Research Wageningen UR, NL) was established. Results and conclusions of this complementary research, as well as practical recommendations based on this research project are presented in this report.


Read report:  Gas foaming research report Oct 2010

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Research on gas foam in 2007 by Marien Gerritzen WUR

Summary report ISSN 1570 – 8616 M.A. Gerritzen Toepassingsmogelijkheden van schuim voor het doden van pluimvee (2007)

Culling animals is an important instrument in fighting infectious animal diseases. To prevent the spread of infectious diseases, from the viewpoint of animal welfare and to prevent infection of humans through contact, animals are preferably culled in the poultry house. Until now, the only available and generally acceptable method was to use CO2 gas.

For poultry houses with a construction unsuitable for gassing, in the Netherlands probably < 30%, methods are being investigated to depopulate the poultry house with minimum human-animal contact. Using foam to cull the animals is a possible acceptable alternative.

Foam can be used in various densities and using various types of gas as a carrier. High-density foam will kill the animals through suffocation. This method is permitted in the USA but suffocation is objected to in the Netherlands from a viewpoint of animal welfare. Adding CO2 to the foam, if the CO2 is released to a sufficient extent and the foam causes no obstruction to the respiratory system, could be an acceptable alternative. However, no form of scientific research has supported this until now.

From the viewpoint of human safety it is essential to avoid or minimise human-animal contact as much as possible. Foam can be used in a simple way with minimum use of personnel so that any contact with the living animals is very limited. In addition, adding foam and therefore moisture will result in a reduction in the amount of dust. If detergents or disinfectants with a virus destroying working are added this can contribute substantially to reducing the virus pressure.

It can be stated in conclusion that using foam to cull animals can be a major alternative to depopulation through gassing but that the consequences for animal welfare have not yet been fully investigated. The minimum human-animal contact and the possibilities for (partial) decontamination are important motivations for further studies into this method.

However, a number of important conditions must be attached to the use of foam as a method of depopulation:

–  The foam must be non-irritating and non-corrosive for animal welfare and human safety reasons

–  There must be no negative effects on the environment.

–  It must not hinder or render depopulation and culling impossible.

Aspects to be studied:

–  What are the effects on animal welfare; rapid unconsciousness; cause of death.

–  Which types of foam do not cause irritation and are safe for the environment.

–  How quickly is CO2 released from the foam (animal welfare).

–  What are the effects on the depopulation process; wait time before the foam has biodegraded; amount of water in the poultry house.

–  Is it possible to reduce the virus pressure in the poultry house and on organic material.

Read report:   Rapport Marien Gerritzen 2007

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