Animal-sourced Food Supply From Circular Food Systems
Figure 1: Framework to assess the supply of animal-sourced food from animals fed LCB. Example shown represents the EL Circular Wholegrain Fixed scenario. All flows are in fresh matter except grass which is in dry matter.
Our analysis revealed that animals exclusively fed LCB were unable to provide the combination of meat, milk, eggs and fish recommended in the EAT-LANCET dietary guidelines, largely due to an insufficient quantity of high quality LCB. In total, the reference diet derived from the EAT-LANCET dietary guidelines contained 71 grams of meat and fish, 250 grams of milk and 13 grams of eggs per capita per day. It was, nevertheless, possible to fulfil these recommendations by adjusting the share of meat and fish while respecting the healthy range. The reference value for pork, for example, is 7 grams, while the healthy range is 0–14 grams of pork per capita per day.
In the EL Circular Wholegrain Fixed scenario, recommended quantities of milk and fish could be met while meat and eggs were 5% and 92% short of meeting the recommended intake in the EAT-LANCET dietary guidelines. In the EL Circular Refined-grain Fixed scenario, the recommended quantities of meat, milk, eggs and fish could be met due to the additional LCB available from the refining of grains (e.g., wheat bran). However, adjusting the shares of meat and fish was still required. Compared to the EL Circular Wholegrain Fixed, the EL Circular Refined-grain Fixed scenario could produce more poultry meat (4 vs. 2 grams of poultry meat) and meet the recommended intake of eggs in the EAT-LANCET dietary guidelines (13 eggs per capita per day). From a health externalities perspective, the consumption of poultry meat is preferred over the consumption of beef and pork 4. Broilers and laying hens, however, were limited in their ability to upcycle all types of LCB and mainly required the co-products from refined grains. This creates a trade-off between consuming healthy whole grains or producing healthy white poultry meat and eggs.
The EL Circular Wholegrain Potential scenario showed the optimal allocation of LCB (in terms of maximising protein production) to different animals (Fig. 2). This scenario resulted in an increase in pork production (to 40 grams per capita per day) due to a pig’s ability to convert low quality co-products and food waste into animal-sourced food. Milk production also increased (to 563 grams per capita per day) as dairy cattle are efficient converters of LCB (especially grassland) to protein. Increased milk production increased the supply of cull cows which produced additional beef. The increase of pork and milk was at the expense of poultry and fish production, thus showing a trade-off between optimally utilising LCB and producing the preferred white meat.
Human Nutrient Supply From Circular Food Systems
Our results showed that the EL Circular Wholegrain Fixed, EL Circular Refined-grain Fixed scenarios and the EAT-LANCET Reference did not meet zinc, calcium, vitamin B12 average nutrient requirements of the human population set out by EFSA (Fig. 3; Supplementary Material). Notably, the EAT-LANCET reference also fails to meet EPA/DHA average nutrient requirements (Fig. 3). The EL Circular Wholegrain Potential did meet the calcium and vitamin B12 requirements but not zinc however, largely due to an increase in milk production (250 grams vs 563 grams). For all nutrients except EPA/DHA (due to less fish), nutrient supply was greatest in the EL Circular Wholegrain Potential scenario. Besides calcium, all three circularity diets outperformed the EAT-LANCET diet on available nutrients.
Greenhouse gas emissions and land use impacts of circular food systems
Overall, GHG emissions were 31% and 28% lower in the EL Circular Wholegrain Fixed and EL Circular Refined-grain Fixed compared to the EAT-LANCET reference scenario. The reduction in emissions was due to the avoided emissions related to the production of animal feed (e.g., nitrous oxide (N2O) from nitrogen fertilisation) and the EL Circular Wholegrain Fixed scenario requiring less grain production (i.e., more grain was destined for human consumption, due to no refining).
Figure 4 shows GHG emissions and animal-sourced food protein produced from all three EL circular scenarios and the EAT-LANCET reference diet. Higher quantities of animal-sourced food (and therefore protein) were produced in the EL Circular Wholegrain Potential and lower quantities in the EL Circular Wholegrain Fixed scenarios which influenced GHG emissions (Fig. 4). The EL circular scenarios include a default GHG emission value (according to the IPCC tier 2 approach) and a range of uncertainty to reflect the uncertainty in GHG emissions (Supplementary Material). Optimally utilising LCB (to maximise protein production from animal-sourced food) in the EL Circular Wholegrain Potential scenario increased default GHG emissions to 477 kg CO2e per capita per year from 367 kg CO2e per capita per year in the EL Circular Refined-grain Fixed scenario (largely due to an increase in milk and pork production, Supplementary Material). The default GHG emission values of all scenarios were within the safe operating space of the planetary boundaries’ framework (511 kg CO2e for food production per capita per year; Willett et al., 2019). In all EL circular scenarios, the upper limit to the range of uncertainty was beyond the safe operating space.
Overall, cropland use was lower in all EL circular scenarios compared to the EAT-LANCET reference diet. However, it was important to note that the EAT-LANCET reference scenario was a global land use average, while the EL circular scenarios were based on EU land use. Further, utilising cropland to produce animal feed also led to an increase in land use in the EAT-LANCET reference scenario. Cropland use was lowest in the EL Circular Wholegrain Fixed and EL Circular Wholegrain Potential scenarios due to the use of wholegrains requiring less land (i.e., less co-products from wheat results in less land required), though differences with using refined grain were marginal. Grassland use of the EL Circular Wholegrain Fixed and EL Circular Refined-grain Fixed were similar while the EL Circular Wholegrain Potential scenario resulted in a higher grassland use, as the use of grassland resources was increased for milk production (Fig. 3).
The milk and beef production in circular food systems was highly dependent on the availability of grassland. Variation exists in the data of quantity and quality of current grassland in the EU-28 depending on the study and definition of grassland (i.e. between managed and natural grassland) and available data sources. We compared the animal-sourced food output (e.g., milk) of the EL Circular Wholegrain Potential scenario with different areas of managed grassland resulting from three different studies/models 21–23. Milk production and beef (from dairy cattle) ranged, respectively, from 326 to 780 and 11 to 37 grams per capita per day (Supplementary Material). Including natural grasslands could further increase the output of animal-sourced food.