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Supermarkets Condemned for use of Non-stun Slaughter for Pigs

Seventy leading animal welfare groups from across Europe have condemned the killing of pigs using carbon dioxide, a method that has left outraged consumers with no way of choosing pork, bacon or ham produced more humanely.

A statement released by Eurogroup for Animals and nearly 70 member societies, including Compassion in World Farming and the RSPCA, called for an urgent move away from the killing method that causes “pain and distress” to many millions of pigs across Europe. In Denmark, Germany, Spain, Sweden and the UK, 85 per cent or more of the pigs are killed using a method long condemned by both science and government animal welfare advisors.

The slaughter method in question involves lowering pigs into a gas chamber containing CO2, causing them to gasp for breath and hyperventilate, causing pain and panic amongst the terrified animals. The gas acidifies eyes, nostrils, mouths and lungs, meaning the animals feel like they are burning from the inside out for 15-60 seconds or more.

WARNING – DISTRESSING IMAGES. Video Credit: Pig Truth from Animal Rights on Vimeo.


The truth is that CO2 killing of pigs is as much non-stun slaughter as simply cutting an animal’s throat and letting them bleed to death. In both cases, animals experience a prolonged period of pain, suffering and distress.

In 2003, the UK Government’s own expert advisory body, the Farm Animal Welfare Council (FAWC) condemned the practice, recommending that gas killing of pigs with high concentrations of CO2 should be banned within five years. Sadly, that recommendation was never acted upon.

Instead of being discarded as some terrible anachronism, CO2 stunning has instead become industry standard. The convenient way of killing pigs.

In reply to letters to their chief executives, ASDA, Morrisons, Tesco and Sainsbury’s confirmed that pigs destined for their stores are killed using the non-stun slaughter method of carbon dioxide. In addition, farm assurance scheme, Red Tractor, confirmed that CO2 gas killing of pigs “is permitted” within its standards.

Even some organic pigs can be killed this way; a spokesperson for leading organic farming body, the Soil Association defended the practice to The Independent, saying “With carbon dioxide stunning, the animals benefit as they stay together as a group with very minimal contact, which minimises their distress ahead of stunning. However, there are 15 seconds or so of some discomfort for the pigs”.

So, where does this leave consumers?

Well… powerless. Except to avoid pig-meat altogether.

As it stands, consumers have no way of knowing whether meat comes from pigs gassed or stunned by any other method. Consumers are left with the very real assumption that if you’re buying pork or bacon, then it may well be from an animal killed in a gas chamber.

Factory farmed pigs, cruelly caged and confined in dark sheds

How can it be considered humane?

The widely accepted understanding of humane slaughter involves a stunning or killing method that is instant or non-aversive. According to the Humane Slaughter Association (HSA), a charity set up more than a hundred years ago to promote humane killing methods, “If a stunning method does not cause instantaneous insensibility [until dead], the stunning must be non-aversive (i.e. must not cause fear, pain or other unpleasant feelings) to the animal.

Against this common-sense benchmark, gassing pigs with high concentrations of CO2 falls well short of the mark.

As far back as 1996, clear scientific evidence highlighted that CO2 stunning for pigs causes severe welfare problems and a high degree of suffering. The study concluded that pigs show profound aversion to the gas which leads to “severe respiratory distress”. More recent evidence suggests that the pigs take 30-60 seconds or more to lose consciousness. That’s an awful long time when terrified and fighting for breath.

In 2004, the European Food Safety Authority (EFSA) also condemned CO2 stunning for pigs as being “aversive” to the animals.

In 2009, the newly adopted EU Regulation on slaughter and welfare expressed disquiet, stressing the importance of exploring a phase-out of CO2 for pigs.

Why condemned then adopted?

So how did a slaughter method so widely condemned become the norm? Because it allows for more pigs to be killed in less time. It also provides more uniform meat quality.

It is “cheap and convenient” for an industry “based on a [high] flow of animals through a meat processing system. It’s cheap because CO2 is not very costly and it allows for a high speed of animals through the system,” said Bo Algers, Professor Emeritus at the Swedish University of Agricultural Sciences, Uppsala.

Larger slaughter plants in the UK and Europe, as well as Australia and South Africa, are now using CO2 killing for pigs. According to the HSA, abattoirs that kill a lot of pigs in a short time (800 pigs per hour or more) see gas killing as often the “most reliable slaughter method”.

The widespread adoption of CO2 killing is part of the wider roll-out of mass automated pig-meat production. It is an evolution of an industrial farming practice that seems to value throughput over welfare and animal sentience.


Leading scientists believe that alternative electric stunning systems or using different gasses may hold the key to more humane alternatives. The use of argon as a non-aversive gas alternative is being investigated along with Low Atmosphere Pressure Stunning (LAPS). LAPS stuns animals by gradually reducing atmospheric pressure and hence the amount of oxygen available for animals to breathe. It mimics the reduction in pressure experienced by military pilots flying at high altitude and is not known to be unpleasant.

Call for Action

With the search for alternatives picking up pace in the wake of publicity, Compassion and the RSPCA have issued a joint statement, calling for “the use of high concentrations of carbon dioxide for the killing of pigs to be legally prohibited; and new, humane systems to be developed and commercially available to replace the use of high concentrations of carbon dioxide” by no later than 1st January 2024.

Clearly, action is needed and the sooner the better.

Non-stun slaughter using carbon dioxide is the pig industry’s best kept and darkest secret. It shows that bringing home the bacon has never been so cruel.

Urgent action is needed by governments and supermarkets to ensure that this version of hell masquerading as ‘humane’ slaughter is seen for what it is and brought to a swift end. 

For readers and supporters in the UK, please click here to take action by writing to Theresa Villiers, Defra Secretary of State, calling for urgent action to ban high-concentrate carbon dioxide killing. 

For others in Europe, we will advise you of other ways you can help and helpful actions once the new EU Commission is installed in December 2019.

Thank you.

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