From soya to swill: Is the 'pig idea' viable?

Written by: RWW | Published:

Launched in June this year, the Pig Idea campaign is gathering pace, but is it a sustainable answer to managing food waste? David Burrows seeks the opinion of waste and food sector experts as to whether pigs should help the UK deal with the six million tonnes food waste it is expected to be landfilling by 2025.

Three months ago a campaign was launched in a bid to change European laws governing what can and can’t be fed to pigs. 

“Humans have been recycling food waste by feeding it to pigs for thousands of years. Reviving this tradition will help to protect forests that are being chopped down to grow the millions of tonnes of soya we import from South America every year to feed our livestock.”

So claimed Tristram Stuart, a campaigner on food waste, when he spoke at the launch of The Pig Idea in June. Put it like that and it seems like a sensible idea. 

Pigs are an effective recycling system, so why not give them a chance to help the UK deal with its mountain of food waste? 

By 2025, the UK may still be burying 6Mt of food waste, so why not open up another channel that will help divert more of it away from landfill? There is more than enough to go around for the pigs, for anaerobic digestion (AD) and for composting.

And yet this is a campaign that is dividing opinion across a number of sectors, including food, catering, farming and waste. Some see it as a ‘no brainer’ while others insist it is ‘pie in the sky’ and could even discourage people from reducing their food waste.

So, is the (pig) idea a good one, both economically and environmentally, and is there any chance of it being successful?

As recently as the 1990s, food waste was collected from catering companies and canteens and sent to pig farms. It was an early example of the circular economy in action. 

Reversing the ban

Foot-and-mouth changed all that in 2001 with the devastating disease thought to have started on a farm where pigs had been illegally fed unprocessed restaurant waste. A ban ensued, first in the UK and the year after across Europe, on feeding kitchen food waste to pigs. 

This is the law that campaigners like Stuart are now trying to have reversed.

“It’s currently legal to feed unsold bread, dairy, fruit and vegetables to pigs so long as the retailer or business is registered with the correct authorities,” campaign coordinator Edd Colbert told food magazine Delicious recently. 

“This is a practice that we are advocating and encouraging, but our longer-term aim is to lift the ban on catering waste and animal by-products which are currently illegal but which, given the correct heat treatment, would be absolutely safe for non-ruminants [pigs and chickens] and also humans to eat.”

Stuart told BBC Newsnight last month this is not a nostalgic return to pigswill but a really well regulated and financially sound system. 

Speaking to RWW recently he says: “Those who produce [food] waste have to pay £80 to £100 a tonne to get rid of it, whether it’s sent to landfill, anaerobic digestion or composting. Recycling food waste [by feeding it to pigs] can, in contrast be a profitable business without any government support.”

Stuart cites the example of a sandwich factory which has saved £100k a year by sending unwanted crusts to be turned into pig food. Other food manufacturers are doing the same with leftover biscuits, cakes and cereals, so why not allow the catering sector to do the same - if properly regulated?


Health and safety risks aside (see below), this could still be a huge challenge given the costs of collecting the waste for delivery to centralised treatment plants. In other words, the idea will face many of the same headaches as those in the AD sector.

Peter Charlesworth from consultants Carbon Statement is currently studying the gaps in UK infrastructure that prevent more hospitality food waste from ending up at AD plants. He has found that the big challenge is making the separation and collection of the food waste commercially viable. There are solutions (due to be published imminently), but extending them to pig feed could be a step too far, he adds: “From a practical point of view and the commercial reality, it doesn’t stack up.”

Others in the waste sector are not even considering the idea. “From a legal point of view it isn’t going to happen,” says Tina Benfield, senior technical advisor at CIWM. “[The ban] came from a European legislation and the UK [gold-plated it] because we were in the middle of foot-and-mouth. It’s a nice idea, but pie in the sky.”

And it’s not just politicians who the campaigners have to convince. The National Pig Association represents a large chunk of the UK’s pig farmers and its general manager told RWW that the idea of feeding food waste to pigs is “well intentioned” but not realistic.

“We don’t disagree with a lot of the elements of the campaign,” explains Zoe Davies, “but who will subsidise the treatment plants they are talking about and how do you get it to the plants? Food waste is also very variable so how do we manage the pigs’ diet?” 

Davies said the campaigners have a “big battle” changing European legislation, but there are signs that the policy side could be changing. 

A House of Commons Select Committee on Global Food Security recently backed calls for relaxing the laws on feeding food waste to livestock, recommending the “Productive recycling’ of unwanted food”, including
“using the food as animal feed” if appropriate. 

More research needed

The case for diverting food waste to pigs rather than bacteria could improve further with more research on the environmental benefits. 

The campaign website claims that “around 20 times more carbon dioxide emissions can be saved by feeding food waste to pigs rather than sending it for AD”. Others agree that there could be benefits. “By sending food waste to AD one can avoid the emissions released through degradation in a landfill,” explains Adam Read, practice director for waste at consultants Ricardo-AEA. 

“However, compare this to the carbon saved through feeding food waste to pigs [given] the energy and water required and carbon emitted to grow feed grains such as wheat and soya; not to mention the use of mineral fertilisers that have a much higher level of embedded carbon energy and greenhouse gas emissions, and it is a no brainer really.”

The food waste hierarchy sets out the most environmentally preferred solution for the management of food waste. Within that, food waste prevention and feeding to people are at the top while redirecting food waste for animal consumption is preferable to energy recovery. 

A WRAP spokeswoman confirms: “If surplus food is generated by businesses we then encourage redistribution to humans where appropriate, or it being used as animal feed provided this is done in compliance with the relevant legislation. Thereafter, anaerobic digestion and composting offer effective food waste treatment options. All of these are preferable to landfilling food waste, both financially and environmentally.”

Those representing AD don’t seem to have an issue with it either. 

“It makes sense that food that cannot be eaten by humans is eaten by animals,” says Charlotte Morton, CEO at the Anaerobic Digestion and Biogas Association (ADBA), who highlights there is plenty of feedstock to go around: “With just 1m tonnes of AD capacity in place and 15m tonnes of food waste generated across the country, there is still plenty more to do to bring waste up the hierarchy from landfill and less sustainable treatment options.”

Indeed, there are some concerns that feeding food waste to pigs will discourage the public and businesses from reducing it in the first place. On the flip side are those for which the idea creates fear rather than nostalgia. 

As Read concludes: “Ultimately, it may be that we the consumer will dictate the popularity of this proposal.”

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