21 December 2022


Dr David Cutress: IBERS, Aberystwyth University.


  • Circular systems and economies aim to improve efficiencies whilst reducing waste by recycling, reusing and refurbishing materials and energy throughout production
  • Within agriculture, many production aspects are amenable to circularisation
  • Livestock production and the animal-sourced food chains are currently one of the least efficient aspects of agriculture, due to high waste and greenhouse gas outputs
  • Circularisation of livestock production processes appears to have the best prospects for maintaining the production of animal-sourced foods sustainably


It is important in modern agriculture to look at our systems in more sustainable and resource-protective ways than ever before. Many resources are finite. In producing outputs from these, we tend to release greenhouse gases (GHGs) and if we continue to deplete these at our current rates the environmental impact will exponentially increase. Across a series of articles, we will be exploring how agricultural systems are ideally placed to fit into circular systems and highlighting different key areas within agriculture where circularity should be focused on. This first article will also act as an introduction to those unfamiliar with the concept of circular systems to provide some background.  


A brief introduction to circular economies and systems

Agriculture, like any other industry, has the main purpose of producing products. The standard approach across industries towards production is a linear system. Linear systems start by taking the core ‘ingredients’ required to make a product, for sale or use, before this product is then eventually disposed of or sent to waste at the end of its useful lifecycle.


From a livestock food supply perspective, the ‘ingredients’ are the soil nutrients, sun and water which are used for pasture production for livestock feed. Pasture can also be replaced, or added to, with purchased or produced feed fodder elements. The other ‘ingredient’, in this initial stage of linear production systems, is the livestock animal itself. Livestock act as conversion machines for transforming lower-quality inputs into higher-quality outputs. These outputs are then utilised and consumed or wasted, either directly or in the form of human waste. In such a linear system, nutrients are constantly being taken from the soil, limiting the amount of pasture growth possible in future production cycles, or requiring that more and more external feed or nutrients be supplied. To prevent constant resource requirements, circular systems are recommended to improve the efficiencies and sustainability of production. These rely on recycling, reusing and refurbishing elements within a production cycle in order to essentially close the loop of material and energy usage. 


Circularity is already somewhat common in livestock production; particularly when using animal waste as nutrients to feed soils and future pasture crop production. The circular livestock chain looks more like this.


Essentially, the more circularity that is achieved between elements of the production cycle, the more efficiency there is. This decreases production costs and improves production sustainability long term. Thinking about the diagram presented above simplistically, if 50% of your ‘Take’ nutrient requirements for pasture can be supplied from a combination of livestock manure and waste, then your input costs will be 50% lower from artificial fertilisers. This reduces the cost of purchase and the greenhouse gas emissions associated with the production, transport and use of synthetic fertilisers.

Another important aspect towards improving circularity is to reduce both the conceptual distances (via innovative production strategies) and physical distances between the take and make steps, along with reducing the material quantity reaching the disposal step. One aspect that assists with this, within livestock food supply chains, is striving for shorter supply chains between farmers and consumers, as this can reduce wastes and losses which occur due to transport, processing and storage, before ultimate consumer utilisation of products. This role of reducing supply chains is an interesting area in farming, it has been discussed in a previous article if you wish to learn more.


Why do we need circular livestock systems?

As discussed, resources on our planet are finite. Resource availability, along with the physical land space available to us set the boundaries for the ability of human populations to survive and grow. Whilst many argue that reducing animal-sourced foods and moving to more vegetarian and vegan diets is essential to feed the global population and reduce environmental impacts, circularising livestock production systems offers a route to maintain at least some level of animal-sourced food. What is not shown in the circular system, but was briefly mentioned in the video above, is that globally, much of the food we feed in our animal systems either directly or indirectly competes with the production of human consumable food. Figures suggest that currently, around 40% of our global arable land is producing feed for animals that are largely human-edible.

It has been calculated, in initial estimations, that by working towards completely by-product and grassland-fed livestock production systems, around 1/3rd of each person’s daily protein need could be supplied globally. This scenario would allow all land optimal for arable production to be used to feed humans, rather than to feed animals. This would lead to a fairly dramatic drop in the level of livestock production occurring. But what it also shows, is that regions with soils and landscapes more beneficial to quality grassland pastures, than to arable crop growth, will work best as the hubs for livestock production. This is highlighted as a role for the Welsh landscape of food production particularly. It also highlights the benefits of ruminant species such as sheep and cows due to their ability to make use of human-inedible nutrients within grasslands, compared to poultry and pigs. However, if regulations on feeding food waste were to be changed, then there is evidence to suggest this would offer a route to feed monogastric animals (particularly pigs most efficiently), provided waste pre-treatments were performed. 


Considerations for circular livestock systems

Whilst these circular systems appear closed-looped, as shown in the previous video, in reality the recycling of wastes and other products is incomplete, or not performed at all. Anywhere within these circular systems where we can improve efficiencies is beneficial to the entire circularity of the system. Furthermore, another aspect that is not highlighted in these diagrams (for simplicities sake) is that almost every step of the cycle produces GHG emissions at varying levels. As such circular livestock production improvements could focus on any of the following;



A more overarching tool, to improve the need for concentrates in livestock production systems, is to consider adding circularised elements for producing alternative livestock feeds with lower environmental and land use impacts. Examples of these include industrial proteins from insects, fungi and bacteria. Such feeds have been highlighted for their ability to take organic matter of lower quality and standard than can be recycled by livestock directly and embed it into organisms which can then be fed to livestock, for conversion to high-value edible proteins. Whilst there is some debate around the produced protein being equally viable for human consumption, the level of consumer uptake for some of the most efficient systems such as insect proteins is currently limited due to socio-cultural aspects. As such, in the short term, these appear to have more acceptance for their use in livestock feeds.


Technologies that can directly or indirectly improve the efficiency of livestock circular systems include those which derive further benefits from waste. These include anaerobic digestion (AD) and various composting strategies for waste, which produce energy and digestate for more dual action recycling and pasture nutrient management. This recycling of waste and energy will be discussed in more detail in future articles.


Circular systems can continually be incorporated in an attempt to achieve as much efficiency as possible. In the examples above, the energy needed for protein production can come from renewable energies in order to improve the impact, but it could also equally come from the livestock production process itself via AD and a combination of these two circular patterns.


Careful nutrient management planning and evaluations in a circular manner can play a key role in intensive systems. Studies of combined crop and livestock integrated mixed farming production have shown that these can reduce environmental impacts by between 39 – 62%, provided careful assessment of plant and animal nutrient requirements, and the cyclic interactions of these, is performed (to avoid external nutrient inputs). Such cyclical studies demonstrated a reduction in profits, due to a combination of losses in achievable crop revenues (as opposed to a scenario where all land was arable) and losses in meat production (due to fodder-only systems sustaining fewer animals than systems supplemented with concentrate). Losses could be minimised to 3% whilst still achieving a 39% reduction in environmental impact despite this. Future subsidy payments may well align with mitigating these minor losses.

Some environments benefit livestock production and are more suitable for livestock than alternatives like crop or biomass production. In such instances, this acts as a possible alternative to local production focuses as it may still be more environmentally efficient to transport produce from these highly suitable locations globally, on balance, than it is to produce them locally in each area. Again such a focus on circularised sustainable systems approaches globally would likely place Wales at the forefront of UK domestic livestock production, though this doesn’t mean that livestock numbers in Wales wouldn’t also have to drop dramatically, to achieve the best sustainability efficiencies.

Ultimately whilst there are changes required from the production side of the livestock food supply system, there are also changes necessary from the consumer perspective. An interesting swiss model, of consumer behaviour impacts on sustainable food systems, assessed 6 strategies that consumers could partake in to improve the situation. One of the strategies involved purchasing food from systems incorporating circularity. The modelling assessed greenhouse gas emissions, land use, diet quality, diet costs, nitrogen surplus and social risks (with social risk being based on ranking a database of social risk hotspots for supply chains which uses 156 social indicators including; ethical nature of labour, forced labour, excessive working time and human health risks).


The findings of this model mapped well with some other similar models. The addition of circularity into a system improved almost all aspects far more significantly than any other strategy. This suggests that there is a requirement for consumers to actively purchase food produced in certain ways, or to change their behaviours, in order to improve the sustainability of food supplies. Organic and circular organic systems need to be valorised by the public in order to mitigate the increased costs associated. What was also noted, as might be expected, is that the best outcomes came from consumers supporting a mixture of these strategies working in synergy.



Increasing the circularity present within livestock systems, in the future, appears to be the only way to assure that animal-sourced foods can add to human diet compositions in an environmentally improved way. Whilst livestock can provide other ecosystem services, (particularly in developing countries, where they provide not just food, but transportation and manual labour) they are unlikely to ever disappear from the food supply chain. However, support for their continued intensive production may be at risk. By optimising nutrient and energy usage and closing waste loops via recycling and reuse, livestock production could reduce both its costs and its globally high environmental impacts significantly. Whilst some of this is achievable at the farm level, broader infrastructure and socio-economic perspective changes will likely be required in order to achieve the best results.


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