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Funding Opportunity - Development of an alternative method to high concentration CO2 for the commercial stunning of pigs

The Humane Slaughter Association and Defra are jointly offering up to £400,000 of research funding for a project to develop a more humane way to stun pigs during commercial slaughter. The funding aims to develop and or validate a more humane method which could replace high-concentration CO2 stunning, which is commonly used for commercial slaughter and has been shown to be aversive to pigs.

Project Summary

  • Up to £400k to develop and validate a demonstrably more humane alternative to high concentration CO2 for commercial pig stunning.
  • Jointly supported by Defra and the Humane Slaughter Association.
  • Reflects both organisations commitment to improving the welfare of animals at slaughter.
  • Proposals should include a comprehensive assessment of the welfare impacts of the method.
  • Proposals should also evaluate the practicality of the method for large scale commercial slaughter of pigs to ensure that the method is likely to be adopted by industry.

Detailed Project Description
The stunning of pigs by direct exposure to high concentrations of Carbon dioxide (30% and above) is commonly used for commercial slaughter of pigs. Research has shown that pigs find direct exposure to high concentrations of CO2 aversive. This has been acknowledged by both the Farm Animal Welfare Committee (FAWC) and the European Food Safety Authority (EFSA). FAWC in its 2003 Report on Animal Welfare recommended that this method should be phased out, whilst EFSA’s 2004 report confirmed the efficacy of the method but noted that it resulted in respiratory distress in pigs. Similar concerns were expressed for poultry and alternative controlled atmosphere systems are now in use within the poultry industry. The use of CO2 in high concentration for the commercial stunning of pigs is permitted under EU and national Regulations, and this method continues to be used in the UK as well as other EU Member States

Following the FAWC and EFSA recommendations, in 2005 Defra commissioned research to look at alternative gases for killing pigs. The results of this research indicated that the use of direct exposure to high concentrations of inert gases is a more humane method as it does not cause aversion. However, despite efforts to encourage uptake by the industry there has been little progress made in using inert gas in commercial slaughterhouses, due to practical issues related to the time that it takes for pigs to become unconscious/death and the practicality of replacing CO2 systems with the new equipment. Defra and the Humane Slaughter Association would like to commission further research that identifies or develops, and validates an alternative and commercially viable method to the stunning of pigs via direct exposure to high concentrations of CO2 in a high-throughput setting

Project aims and objectives

The research & development shall investigate a method that is both more humane than direct exposure to high concentration CO2 and that would be feasible to implement in practice and thus likely to be widely adopted by the industry.

The objectives for this work shall include:

  1. Assessments the effectiveness of the proposed method for stunning adult pigs using defined parameters and including an assessment of practical viability, installation and operating costs, physical damage to carcasses and effects on meat quality.
  2. Measurements of time to loss of consciousness, duration of loss of consciousness and the time between loss of consciousness and death.
  3. Behavioural, physiological and neurological assessments of any suffering and distress prior to loss of consciousness. This shall include an assessment of aversion to the proposed method.
  4. A commercial feasibility and economic cost-benefit analysis of the proposed method.

All scientific assessments of the effectiveness and animal welfare impacts of methods should follow the procedure set out by EFSA (,0.pdf) for validation of stunning methods.

Application Process


Applications are now closed. 


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