The role of farm animals in a circular food system

If we use farm animals for what they are good at - converting by-products from the food system and grass resources into valuable food and manure - they can contribute significantly to human food supply, while at the same time reducing the environmental impact of the entire food system. By converting these so-called low-opportunity-cost feeds, farm animals recycle biomass and nutrients into the food system that would otherwise be lost to food production. Rearing animals under this circular paradigm, however, requires a transition from our current linear food system towards a circular one. Here we present a biophysical concept for the role of farm animals in a circular food system, essential for meeting dietary recommendations within the boundaries of our planet.