Upcycling biomass in a circular food system : The role of livestock and fish

Abstract

A more circular food system is increasingly proposed to address the challenge of feeding a growing world population while limiting environmental impacts and resource use. A circular food system prioritises resources for direct food supply to avoid feed-food competition. The role of animals is to upcycle resources unsuitable or undesired for human consumption, so called low-opportunity-cost feeds (LCF) into animal-source food. This thesis evaluates the potential of various animals in upcycling LCF in a circular food system by applying an optimisation model that allocates available LCF to that combination of animals that maximise the supply of human digestible protein (HDP) to a EU-28 case study. We first explored the potential of common livestock species in the EU (e.g. pigs, laying hens, broilers, dairy cattle and beef cattle) under various productivity levels. Optimal use of LCF required livestock systems that had a high conversion efficiency (laying hens, dairy cattle), were best able to valorise specific LCF (dairy cattle for grass; pigs for food waste) and could valorise low quality LCF due to their low productivity. When, in addition, considering fishcurrently the only natural source of the essential eicosapentaenoic (EPA) and docosahexaenoic (DHA) ω-3 fatty acids-while demanding EPA/DHA requirements are met, fish provide nutritious food via both capture fisheries and fish farming. Even if capture fisheries rebuilds stocks and prioritises edible fish for human consumption, it can only fulfil 40% of EPA/DHA requirements. The farmed fatty fish needed to meet these requirements depend on fisheries by-products to meet their EPA/DHA requirements and livestock slaughter by-products to meet their high fat and protein requirements. A circular food system thus requires a combination of co-dependent animal production systems, tailored to the available LCF and the desired nutrient output. As the availability of food leftovers as LCF is currently restricted by legislation and other barriers, we explored the potential of food leftovers currently not used as LCF. Potential to increase animal protein intake was highest for, currently banned, household waste (+12%) and livestock byproducts (+18%) that are allowed in fish feed but currently not used and appear essential to meet human requirements of EPA/DHA ω-3 fatty acids in a circular food system. Improved use and legalisation of inevitable food leftovers can improve the resource use efficiency of both current and future circular food systems. When allowing all LCF in a circular food system, livestock and fish provide an HDP intake up to 39 g per capita per day, less than current animal protein supply but meeting 65% of total protein requirements. A circular food system, thus, requires a reduction in ASF consumption, and a change in the type of ASF we consume, where fish and milk become more prominent. While the used food systems approach illustrates the potential of animal production in a circular food system, it provides little direction to farmers in achieving sustainab...

Untapped power of food system by-products to increase global food supply

“…To estimate the potential availability of livestock by-products we first converted the production quantities of end products (cattle, pig and poultry meat) from FAO (2021) to live weight using dressing percentages from FAO (2017) and then multiplied those with the ratios of the processed by-products (poultry by-product meal, poultry oil, blood meal, hydrolyzed feather meal, meat meal from pork meat production, poultry oil) from van Hal et al (2020).…”

“…Increasing the use of food system by-products such as crop residues, food processing byproducts, and food waste, has been proposed as a solution to increase the efficient use of resources (van Kernebeek et al, 2016;Schader et al, 2015;Röös et al, 2017;van Hal et al, 2020), to reduce the food-feed competition (van Zanten et al, 2018) and to increase the circularity within food systems (Billen et al, 2021;van Hal et al, 2019). In addition, the use of food system by-products as feed can reduce the agricultural environmental pressure by minimizing environmental impacts such as climate change emissions and the need to occupy inputs such as arable land, fertilizers or water for feed production (van Kernebeek et al 2018;Schader et al, 2015;van Selm et al, 2021;van Hal et al, 2019).…”

“…Since the different food production sectors, i.e. crops and both terrestrial and aquatic animals, are tightly interlinked via feed use, a systemic view of the food system is needed to achieve the goals of circularity (Korhonen et al, 2018;Van Hal, 2020). However, studying the potential use of by-products for animal feeds at global scale is challenged by the lack of harmonized datasets of both feed material flows as well as the availability of the by-products.…”

Balancing animal-source food intake between nutritional requirements and sustainability impacts

“…Part of grass resources are sourced from marginal areas or from temporary grassland with an agronomic function in crop rotations. Grass resources that exceed this threshold come, however, with opportunity costs, and therefore need to be critically evaluated (Van Hal, 2020).…”

“…The resource allocation model was developed in General Algebraic Modelling System GAMS version 30.3. Previously, it has been employed for analyses on the potential for ASF based on current LCB on EU level (Van Hal, 2020;Van Hal et al, 2019a;. In these assessments,…”