Pre-slaughter stunning under scrutiny in UK

18-05 | |
pre-slaughter stunning
Loading pigs for transport to the slaughterhouse. Photo: Ronald Hissink

Organisations in the UK pig sector will form an expert group to look at the pre-slaughter stunning of pigs. This group will revisit current methods and will try to fast-track a review of new ways to make the end-of-life process as painless and stress-free as possible, the British National Pig Association reports.

The group includes veterinary surgeons, scientists, academic researchers and technical specialists from Britain’s leading pig producers and supply chain, the British levy board AHDB, the NPA and assurance body Red Tractor, as well as colleagues from Europe and Australia. By working in a coordinated way, the aim is to take a responsible and global approach.

Controlled atmosphere exposure to CO2

The group will particularly focus on a review of controlled atmosphere exposure to high concentrations of CO2. This method offers some benefits compared to others. For example letting the pigs remain in groups, which can be less stressful from a handling perspective than stunning them individually. The process is also largely automated, reducing human handling and risk of error, the NPA says.

Strongly aversive

However, CO2 can be strongly aversive to pigs – although this is minimised by ensuring loss of consciousness within 15 seconds. The fact that pigs display physical signs of activity during the time up to loss of consciousness, but also show reflex movements after they have lost consciousness, further complicates assessments of the practice.


There are alternatives, and some that have been investigated include use of inert gases, electrical stunning, low atmospheric pressure stunning and nitrogen foam. While research programmes globally are investigating these new methods, none are yet at the stage where they can be commercially adopted.

“The stunning and slaughtering process is an extremely important and sensitive subject, and, therefore, can often also be quite contentious’’, NPA chief executive Lizzie Wilson comments. “Unfortunately, the outcome is that much of the commentary has become driven by emotion, rather than logic at a time when we should be focused on evidence, animal welfare and practical viability. More importantly, the narrative fails to recognise the slaughter of animals is quite rightly one of the most regulated (by government), observed (by vets and trained staff) and closely monitored (by CCTV) practices in industry.’’

“Despite this, we acknowledge concerns expressed by citizen groups and welfare campaigners that slaughter could and should be more humane. It goes without saying that there are also areas where the process could be improved – science moves on, as do technologies and opportunities to share information and collaborate. That is why I’m very pleased that key players across the UK pig sector have teamed up to form a new working group to look at pre-slaughter stunning of pigs.’’

Ruud Peijs International Journalist
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