Rising scarcity of agricultural land and climate change threaten the food security of the growing global population. Since plant-based biomass from agriculture serves as the basis of the global food system, the total gain of food derived thereof must be maximized. For biological and technical reasons, the direct extraction of plant-based food is incomplete, resulting in a multitude of non-edible residues compared to edible extracts. The non-edible biomass can serve as feed for livestock, thereby significantly expanding the total amount of human food produced from the same plant-based biomass grown on a given area of land. When livestock production is balanced within this circular system of utilizing non-edible biomass, the overall ecological footprints of food production reach their minimum. Conversely, production intensities above circularity as well as abstinence from livestock production increase the footprints. Therefore, the non-edible biomass must be considered a valuable yet limited resource to generate additional human food through livestock. It should be utilized with high efficiency, e.g., through proper feed management and husbandry practices that also promote the longevity and health of the animals. In summary, future livestock systems are an essential part of a comprehensive approach to utilizing agricultural biomass in a sequence of priorities: plant-based food for humans first, followed by feed for livestock, and lastly, other purposes such as energy (food > forage > fuel).