In the ongoing research, discussions and debates on the role of livestock in our food systems, the SFT acknowledges the complexity of the arguments being made from a wide range of perspectives. We believe that people have the absolute right to choose their own diets, especially those who for ethical, health or environmental concerns decide to eat a vegan or vegetarian diet. In the spirit of open exchange, the SFT feels that there are important issues to be explored around the question of moving to a wholly plant-based diet, globally, and in this piece, researcher Robert Barbour considers this in relation to the broader need for food security.

How are we going to feed an increasingly hungry planet, without crippling the life support systems on which we depend? It’s an existentially important question, the solution to which will require action on a myriad of fronts. Yet, whenever this issue is raised, there tends to be just one topic that dominates the discussion: the role of livestock.

There are very good reasons for this, of course. Anyone with even a passing interest in the subject will be well aware of the many ways in which livestock affect human and planetary health. But while there is no denying the immense harm that intensive production continues to cause, livestock can also be a tremendous force for good. Put simply, the social and environmental impacts of rearing animals for food are complicated and context-dependent – and nowhere is this more evident than with the relationship between livestock and food security (a measure of the extent to which people have ready access to a nutritious supply of food).

The role of animal-sourced foods

Animal-sourced foods (taken here to mean meat, milk and eggs from livestock, but not fish or wild game) are a key component of diets the world over. They supply us with a third of our protein and significant quantities of other essential nutrients that can sometimes be relatively difficult to obtain from plants – just one of the reasons why livestock are particularly vital in parts of the developing world where undernutrition remains a debilitating problem. Livestock can also produce food from grasslands and other resources that humans can’t cultivate or eat, while the manure they supply (although perverted into little more than a toxic waste stream in many intensive farming systems) remains a key and sustainable source of fertility across millions of acres of cropland – a positive relationship that could be reinstated across much of the developed world if livestock and cropping systems were to once again become better integrated.

Food-feed competition

At the same time however, the way in which we currently rear much of our livestock represents a massive and unsustainable drain upon the global food supply. The reason for this is ‘food-feed competition’, an often-overlooked trade-off between intensive livestock and crop production, brought about by the increasingly widespread practice of feeding human edible crops to animals. It’s an approach that generally improves the productivity of livestock systems, due to the high energy and protein concentrations of arable crops, and which many would argue also improves their sustainability, as it allows farmers to increase production while using less land and producing fewer methane emissions per kilo of product.

While this has enabled us to keep satisfying our near-insatiable appetite for animal-sourced foods, it comes at a heavy cost. All livestock (even pigs and poultry, which are often seen as being more sustainable because they can better convert grain into food) are highly inefficient at converting human edible crops into meat, milk and eggs, and this means we have ended up in a situation where vast quantities of calories and nutrients potentially available for human consumption are instead lost from the food system. The scale of this wastefulness is frightening: 40% of global arable land is now used for feed crop production, an area which, if it were to be used instead for human food cropping, could feed an additional 4 billion people.

This isn’t to say that giving any human edible crops to livestock automatically constitutes a crime against food security. Livestock can still make a positive contribution to our food supply when they are being fed a very limited quantity of human edible ingredients, as is the case as a global average with cattle, the majority of which obtain much of their feed from grass. (Pigs and poultry, on the other hand, represent a net drain on the world’s protein supply, as their inability to obtain most of their feed from grass – even when reared extensively – means they are much more reliant upon arable crops. This holds true, of course, for intensive beef systems as well.) Practical constraints, such as difficulties in meeting quality specifications due to poor harvest conditions, also mean that the feed market can sometimes be the only viable option for crop producers. In any case, food security is not the only lens through which to judge the sustainability of feeding edible crops to livestock. Nevertheless, there is no getting away from the fact that the vast area of arable land currently used for growing feed crops constitutes an unacceptably wasteful use of a finite resource which, when combined with the ongoing surge in demand for animal-sourced foods, threatens the conversion of the world’s remaining wildlands – an environmental catastrophe we must avoid at all costs.

Food-feed competition, therefore, represents a massive flaw in the argument that, for environmental reasons, we should intensify livestock production even further, and shift from eating red meat to pork and chicken, a case that has been made by the Government’s advisory body, the Committee on Climate Change. What, though, are the alternatives? One solution is to stop eating animal-sourced foods altogether. But while going vegan would clearly resolve the problem of food-feed competition, this argument has its own blind spot when it comes to the relationship between livestock and food security, in that it fails to account for the ability of livestock to produce nutrient-dense foods from grass and other feedstuffs, such as crop by-products and food waste, that we can’t or don’t want to eat.

The value of human inedible feeds

This so-called ‘upcycling’ of human inedible feeds is what livestock do best, and despite the widespread use of arable feed crops, it’s still a role that many livestock (especially in ruminant systems) fulfil today. The precise significance of this role to the global food supply is difficult to assess, as disentangling the relative importance of different feeds is not straightforward. Fortunately, a few studies have attempted to calculate the productive potential of a scenario where livestock are entirely limited to feeds that humans can’t eat, their numbers and output determined by the current grassland area and availability of crop and food waste. These studies estimate that globally, somewhere between 7-18 grams of protein per person per day could be provided by ruminants reared solely on grass – a much higher figure than the 1-gram total that is sometimes used, incorrectly, to disparage the contribution grasslands currently make to our food supply. (Their exact contribution isn’t known, but it is probable that a high proportion of the 13 grams of protein per capita produced by ruminants today comes from grass). Add the contribution from crop by-products and food waste, and feeding livestock solely on inedible feeds could produce somewhere between 9-23 grams of protein per person per day (around 20-50% of the world’s total requirements), as well as 10% of our energy and iron needs, 20% of our calcium and zinc needs, and a massive 75% of our vitamin B12 needs.

These are undeniably significant numbers, with the critical point being that they represent an additional and entirely complementary supply of food to that produced from croplands. There is, however, a catch. While the figures above would enable a much-needed increase in animal-sourced food consumption in parts of the developing world, they would represent a major reduction in the West. In Europe, for instance, intake would at least halve, from the current figure of 51 grams of livestock protein per person per day. Which animal-sourced foods would be hit hardest is less certain as this would partly depend upon how feed is allocated, although it’s safe to assume there would be an especially large drop in chicken consumption, the livestock species perhaps most reliant on arable crops and least suited to consuming waste feeds. Ruminants, on the other hand, would continue to be important because of their unique ability to turn grass into food, meaning red meat and dairy consumption probably wouldn’t have to decline so steeply, at least in countries like the UK which are particularly well-suited to grazing livestock.

Nevertheless, even where it proves possible (and desirable) to maintain consumption of some ruminant products, we will still have to eat much less in the way of chicken and pork. The simple fact remains, then, that if we are to turn the livestock sector into a wholly positivecontributor to the food supply, the developed world is going to have to cut down dramatically on the amount of animal-sourced food it eats.

Are livestock an unnecessary environmental burden?

Some people would go even further than this, pointing to studies which have not only have suggested that the world could be fed on a vegan diet, but have also claimed this would use less land and produce fewer emissions than any scenario involving livestock. For these reasons, it is argued, a food secure future does not require livestock, and so we would be better off without them.

It’s a seemingly compelling argument, but does it stand up to scrutiny? To be clear, this question relates to the outcomes of a global conversion to veganism, not to the rights of  individuals to be eating a healthy, sustainable and ethically-sourced diet, whether or not it includes any animal-sourced foods, and it goes without saying that people have the absolute right to choose what diet works best for them. A full exploration of the environmental credentials of different planetary diets is beyond the scope of this article, but a few issues are worth raising here.

The key point to make is that a vegan future would lack the environmental benefits that well-managed livestock can deliver. Probably the clearest example of this comes with the vital role grazing livestock play in supporting a wide range of habitats and species. When integrated with crop production, livestock can also play a hugely beneficial role in the restoration of degraded arable soils, and in reducing nitrogen fertiliser and other agrochemical use, by enabling systems that generate and recycle much of their own fertility through rotations designed to break weed, pest and disease cycles naturally. In addition, although a vegan future may require less land overall, a food system including livestock fed entirely on inedible feedstuffs would only require 75% of the arable land needed for a vegan diet because of the additional supply of calories and nutrients made available, and so might provide more space for lower-yielding but less destructive systems of crop production.

A lesser reliance upon arable land might also afford a little more breathing space to deal with the threats posed to crop production by climate change, which brings us back to the question of whether livestock are necessary for future food security. Climate change is already hurting crop production in many parts of the world, and it’s a problem that is only going to get worse. The livestock sector will not be spared this trauma either – so becoming a society of carnivores is clearly not the solution: the point, however, is that with climate chaos increasingly threatening our ability to produce food of any type, surely it makes sense to have as wide a range of resources to call upon as possible? The worldwide adoption of a diet reliant upon an arable area confined to just 12% of the world’s ice-free land surface, which neglects a source of food that could provide us with 20-50% of our protein requirements and which would economically disenfranchise the 1.3 billion people whose livelihoods depend upon livestock, would therefore seem a risky prospect, especially in those regions less well-suited to crop production because of their poor climate and challenging topography.

Food quality and local perspectives

This local food security perspective becomes especially important when we look at food quality, rather than just quantity. Perhaps the clearest example of this comes with how different regions might achieve a sufficient intake of all the essential amino acids (the building blocks of protein) on a vegan diet. The only crop grown in globally significant quantities that has a complete amino acid profile comparable to that of animal-sourced foods is soya, which would therefore have to assume a critical role in the protein supply. This is particularly true when it comes to achieving a sufficient intake of lysine, the amino acid most difficult to obtain in a plant-based scenario. Soya production could certainly achieve this at a global level – in a sense it already does, it’s just that most is currently fed to livestock – but there is a major problem with this approach. Most of the world’s production is currently concentrated in Brazil, Argentina and the US, and while there is undoubted potential for continued expansion in more temperate climates (including, at least to some extent, the UK, where the area under cultivation has recently risen sharply), it’s unlikely that it will become a viable commercial crop in all areas. In the UK for instance, soya can’t readily be grown further north than the Humber.

Synthetic amino acids

It goes without saying that a diet which may necessitate imports for the supply of a key nutrient, raises some grave national food security concerns. Is there, then, an alternative way to provide a vegan diet sufficient in lysine in regions not suitable for soya production? Synthetically produced amino acids are one possibility with undoubted potential, although it’s far from certain that the public would be happy for these products to form a key component of their diet – just one of the reasons why lab-grown foods more generally may not be the silver bullet some claim. Another option is to meet our amino acid requirements by consuming a range of crops which, although individually deficient in one or more amino acids, when eaten in combination enable a complete protein intake. However, a recent paper which modelled this possibility in Scotland – a country with relatively little croppable land – suggests that while it would be theoretically possible to achieve a sufficient intake of all essential amino acids from a mixture of domestically grown cereals and pulses, in reality this would be extremely difficult, if not impossible, due to the various practical constraints involved in growing the peas and beans necessary for supplying lysine.

Whether it would be socially and environmentally sustainable for arable-poor countries like Scotland to achieve protein self-sufficiency without the use of any livestock is even more questionable. Of course, 100% self-sufficiency is probably not an achievable (let alone desirable) aim for any country, and there are at any rate a host of other factors unrelated to livestock that are critical to ensuring national food security. Nevertheless, as climate change increasingly disrupts the global food trade, maintaining at least some level of domestic self-sufficiency is going to become an increasingly key consideration.

Determining the value of livestock to food security is, then, in part a question of resilience, especially in the face of climate change and the slew of problems it will inevitably exacerbate. Rising undernutrition, increased barriers to trade, steadily degrading arable soils and declining crop yields: all of these are likely outcomes over the coming century that point strongly towards a continued need for livestock – providing, of course, the animals are reared in ways that augment, and therefore relieve the pressure upon, what will be an increasingly stressed supply of plant foods. Achieving this positive vision of livestock production won’t be easy. Quite apart from anything else, it will require a major reduction in intensively produced animal-sourced food consumption in a society hooked upon cheap meat. If we succeed, however, then we will have taken a major step towards building a food secure and sustainable future.