Grazing livestock in a world of climate change: do they have a role?

By Dr Elin RöösSwedish University of Agricultural Sciences & visitor at the Environmental Change Institute at the University of Oxford

"What role of grazing livestock in a world of climate change and diet-related disease?" was the overarching question being discussed at an event in Bristol last week organised by the Sustainable Food Trust (SFT).

The SFT is a charity founded by former Director of the Soil Association, Patrick Holden, in 2011 with the aim to “enable all farmers, scientists, citizens and policy-makers to transition towards systems of food production that don’t do damage to the environment, or our health”. Coming from the organic movement the SFT naturally holds grazing animals dear at heart and last year a blog post by SFT’s Richard Young arguing to eat more, not less, beef and sheep meat spurred off a red meat debate between Richard and FCRN’s Tara Garnett. Despite this debate and despite the fact that the event hosted members from the National Beef Associationthe National Farmers Union and the Pasture Fed Livestock Association and other organisations representing the production side, discussions were throughout the day held at a very balanced level. I got the impression that all attending were honestly interested and susceptible to what the scientific community had to say on the issue.

The event presented an impressive list of reputable scientists. First off giving a presentation was Professor Pete Smith from the University of Aberdeen. With hundreds of published papers on the issue of agriculture and climate change mitigation and lead author of the IPCC report on this issue, Pete made a few critical things very clear:

  • Demand for meat must be moderated. He backed up this statement by showing results from numerous studies which have looked at the impact on GHG emissions and land use change from different diets including the ones from Stehfest et al. 2009Popp et al. 2010 and Bajzelj et al. 2014. The study by Bajzelj is interesting as it shows that even if yield gaps are closed globally, currently available land will not be able to deliver the food needed in 2050 if current consumption trends are maintained.
  • The production of ruminant meat emits a considerable amount more GHG per kg than the production of pork and poultry (not to mention plant-based protein) due to methane emissions; grazing animals more than animals fed concentrates due to slower growth rates. And these results come out the same whatever unit is used for comparison; kg of meat, kg of protein, kcal etc. and including indirect effects from growing soy on deforested land.
  • Pastures cannot continuously sequester large amounts of carbon.  Although flux measurements have shown carbon sequestrations rates of 1 ton of C per hectare per year (Soussana et al. 2007), these numbers cannot be confirmed when the actual C content in the soils is measured.

Pete illustrated the last point with a simple mass balance example. If soils did sequester 1 ton of C per hectare and year for hundreds of years we would now have soils with incredible carbon levels which are just not found.  Pete continued to emphasise however, that degraded land and ill-managed pastures do have great potential to sequester carbon if management is improved and carbon input increased. However, the yearly amount of carbon sequestered will gradually level off as the soil reaches a new equilibrium. What Pete presented on the issue of soil C sequestration was confirmed by Professor David Powlson and Dr Ute Skiba in following sessions. The FCRN has a summary of the soil carbon sequestration issue which can be found here.

But everything is not climate. We need also to cater for the fertility of soils. I would say that it was generally agreed by the speakers that introducing ley (cultivation of grass) into annual crop rotations is a good way of doing so, as it improves soil structure and adds organic matter (under the right conditions). So have we found a role for grazing livestock here? Can the need to include ley in monoculture crop rotations justify the keeping of sheep and cattle? I would argue that in theory it cannot as ley can be introduced in crop rotations perfectly fine without introducing animals. Preferably the biomass is then harvested and used to produce e.g. biogas, resulting in both energy and renewable fertilizer in the form of digestate that can be used to fertilize subsequent crops with high precision. Yes, no meat would be produced from the grass in that case, but then we need to remember again the need to manage consumption, so it comes back to the amount of beef meat and dairy we need. In addition, the energy produced could for example be used to power closed-loop aquaculture systems giving us fish instead of beef, or the ley biomass could be used to produce meat from non-ruminant animals such as horses, rabbits or even insects. Reality is a bit different from theory however, especially in the short run, and raising ruminants on the leys introduced into monocultures might be a way of financing it all. However, then we must remember that the animals are introduced for economic reasons and not because introducing ley in a crop rotation inherently requires animals to be put on it.

SFT’s Richard Young ended the morning session by saying a few words on the issue from a SFT perspective including showing a picture of a huge monoculture soy field warning about what is happening to the soils of the earths. Professor Powlson confirmed that there are surely some soils in a terrible state but that the threat of poor soils should not be exaggerated, as across much of the earth soils are in reasonable shape.

The afternoon started off with a session on the health implications of eating grass-fed meat and dairy foods. Four speakers dug into that issue and the overall conclusion that emerged could be put very briefly:

  • Although meat and dairy from grazing animals have a more favourable fatty acid composition than animals raised on concentrates, the overall health impact at a dietary level (in which the choice of vegetable oil used in cooking, or whether butter or plant-based margarine is used as spreads has a high importance for the overall fatty acid composition of a diet) is still unknown.

Ok, so if the production of meat from grass-fed animals is more GHG demanding, pastures have limited potential for continuous sequestration of C, the animals themselves are not necessary to retain or improve soil fertility [1], the health impacts of grass-fed beef is unclear and demand needs to be curbed – what is then the role for grass-fed cattle?

One obvious point that is always raised, including at the SFT event, is the importance of livestock for the livelihoods of the poor. In many regions cattle provide very much needed nutrition but also serve several other functions such as providing draft power, transports, capital placement. But the need for livestock in these situations cannot justify the keeping of livestock in countries like the UK. Rather one could argue the contrary: if there is a limit to the livestock numbers this planet can support maybe we should let the ones who need them the most, and where they are truly multifunctional, raise them.  But one could also argue that it makes sense to raise these water and land demanding animals in countries where these resources are abundant (even though the fact that the land availability is caused by historic deforestation complicates things a bit). Consequently, the cattle and dairy industry in countries like the UK could then be motivated by the country having excellent conditions to raise livestock with a low environmental footprint per kg of product produced. This argument relies then on the ability for this meat to reach the people around the globe needing this nutrition most, which requires a globalised market and increased purchasing power of the poor. Although trade undoubtedly will be increasingly important to provide food security for growing urban populations, I have some doubts as to whether we should be shipping beef and dairy products around the world. And would these products really replace other ‘worse’ production system (which is the whole point in producing them here where we can do it ‘better’) or just add more animal derived products to the market, hence increasing consumption? In addition, many are calling for the need for more localized food systems.

So maybe we need to search for other ways to defend grass-fed livestock production in countries like the UK or Sweden where I am from. But first let’s stop for a while and reflect upon why so many are struggling to find ways to defend grazing animals. It is not only the farmers and industries into grass-fed meat that want to find reasons to justify this type of production; a lot of scientists and other organisations are also doing so.

One aspect is of course the aesthetic value of grazing animals, a factor not to be underestimated. But I also think that raising animals on pastures feels intuitively right. It seems sensible, natural and good to let these animals with their fascinating digestive system turn the for us humans inedible biomass of grass into products that a majority of the global population seem to enjoy so much: meat and dairy. In a sense it is how things have always been done, and although pulling out the ‘traditions’ argument is a bad way of justifying behaviour (think of slavery for example) it is an important influence on our attitudes and assumption.

Anyway, can this gut feeling be put into scientific evidence? One that has tried to capture this aspect is Professor Mike Wilkinson, who just before lunch presented results from his paper “Re-defining efficiency of feed use by livestock”.  In this paper Wilkinson et al. shows that if one considers feed conversion ratio in terms of the human edible energy or protein input per produced amount of human edible energy or protein (instead of the more conventional measure of kg feed in per kg meat out), grazing animals shows the greatest efficiency, far better than even pig and poultry. However, it needs to be remembered that ruminants still emit methane, so although resource efficient in this sense they will still be climate impacting.

In addition, as was raised by someone in the room, grasslands are not a ‘free’ inexhaustible resource and using them for ruminant production must be weighed against their potential use for bioenergy production, forest plantation for climate mitigation or rewilding for biodiversity conservation (and some grassland is suitable for crop production although the climate consequences of ploughing them up must be taken very seriously). Which brings us back to demand again. Do we need beef and dairy from pastures or can enough food (in a resilient way) be produced on existing arable land considering different levels of managing demand? Or should we take pressure of arable land by producing more from pastures. In that case how much do we need?

Taking about biodiversity, the last session of the day centred on this issue. Jerry Tallowin from Rothemsted Research showed how the biodiversity of what are often monocultural grasslands in the UK could be greatly enhanced by sowing more legumes and forbs. Dr Abi Burns from the Royal Society for the Protection of Birds expressed concerns about the decline of bird populations and highlighted the importance of the High Nature Value farming (low intensity farming) for preserving biodiversity in the agricultural landscape. I noticed that the discussion here centred on the need to enhance the biodiversity of the UK grasslands. In Sweden, the discourse when it comes to livestock and grasslands is very focussed on the fact that animal numbers are diminishing quickly, making it difficult to keep pastures from rewilding or being afforested. Taking into account that only 1% of Swedish land is made up of these semi-natural pastures that hold some of the most threatened species and eco-systems, and the rest of the country is mainly planted monoculture forest, grazing livestock play a crucial role in preserving biodiversity in Swedish as a whole. However, these pastures could of course be kept open manually or mechanically at a much lower carbon cost, and so the choice of doing so with livestock is again a question of mainly tradition, aesthetics and economy. (Although some species do depend on animal dung.) 

Although there was some mention of the low use of antibiotics in grazing systems, which is a proxy for animal health, very little attention was spent during the day on the wider issue of animal welfare.  Curiously enough as I find animal welfare one of the strongest cases for grazing livestock. If one gives weight to the natural behaviour side of animal welfare, it is quite clear that being able to forage outside, and in the case of suckler and lamb production, allowing the off-spring to be with its mother has some very strong animal welfare benefits. And these animals are healthier.

So what did this day give in terms of conclusions? I think it was a great event in terms of mutual learning on the complexities of the whole issue. However, when it comes to answering the overarching question about grazing livestock’s role in a sustainable food system, more research is needed and the discussion must go on.  In terms of research questions, the most interesting and important ones for me include determining the need for animal products from grasslands in future diets under different assumptions about the possibility to curb demand, as well as how agricultural systems are best designed to provide food and energy justly to a growing population, while preserving soil fertility, increasing resilience to climate change, mitigating climate change and increasing biodiversity and the attractiveness of landscapes. In terms of discussions, the SFT provided an excellent arena for this and I hope they will carry on in this direction.

Elin Röös is a postdoctoral researcher at the Swedish University of Agricultural Sciences working for the Future Agriculture initiative at the same university, which is a strategic multidisciplinary research platform that addresses the sustainable use of natural resources with emphasis on agricultural production and food systems. Currently she is visiting the Food Group at the Environmental Change Institute at the University of Oxford, working with future scenarios for protein production and consumption, and engaged in the FCRN network.

[1]There might be reasons why animals are still better for soil fertility like reducing soil compaction. In addition, I don’t know whether consequences for soil fertility from using digestate instead of manure are well understood yet.

This article originally appeared on the FCRN website - you can read the original here.

Photo of grazing cows by Jusben, morgueFile

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