Modelling a Role for Animal Sourced Food in Sustainable Diets

The role of livestock in sustainable food systems is an area of ongoing development, requiring a careful balance of assessment at the animal, system, and human nutrition/wellbeing levels. However, such assessments are made more difficult by the lack of consensus in methods and perspectives, and many studies focus on only one of the above levels, leading to a “race to the bottom” focus to minimize impacts in terms of carbon footprint or other single indicators, many of which are poorly correlated (Ridoutt et al. 2017, Harrison et al. 2021). This misses the biophysical flows between systems, supply chains and/or stages of production, leading to biased results that may not reflect the true context and impact of food production (Harrison et al. 2021). To address this, a circular agriculture/circular economy perspective can be applied, specifically capturing nutrient flows and recycling of mass and nutrient between and within food chains or other processes (Van Zanten et al. 2018, 2019). Such methods can be used to compare the net impacts of different proposed changes on not just specific product systems, but product sectors, or even on a global level.