Given the global demand of proteins predicted for 2050, a transition of our current agricultural model is required. An agroecological model proposes to meet these needs while producing with ecological foresight, but also considering social and economic issues. Livestock rearing in order to meet protein needs is where agroecological principles and the more industrial accepted term of sustainable intensification overlap in certain areas. Multiple definitions of sustainable intensification have been proposed, however, many have a focus on an increase in productivity on already cultivated land while reducing environmental degradation and sparing natural habitats from agricultural expansion. Animal products, as demonstrated within this review, can contribute to a global diet within a limitation of 11–23 g of protein/person/day through agroecological practices. Animal protein can be included if livestock are fed only on pasture, waste or by-products; no scenario exists in which livestock could continue to be fed on human-edible crops. Agroecological practices are already being used by smallholders globally, however, barriers exist to scaling up and out these practices, which require a shift in the policy framework to value and transfer the knowledge of agroecological farmers and increase their access to public resources such as infrastructures. As currently both large-scale agri-industry and smallholders provide for the global population, a strategy that includes both could be favoured. Coupling the upscaling of agroecological practices used by smallholders and transitioning intensive agriculture towards an agroecological model using sustainable intensification as a bridge to implement agroecological practices could help ensure global protein requirements in 2050.
