This part describes challenges to improving sustainability during the production of food of animal origin. Some potential advancements in the sustainability of producing food of animal origin, such as feeds that do not compete with human nutrition, plant and animal breeding, trends in animal nutrition, potential alternative protein sources, alternatives of animal products in nutrition, including lower food losses, are discussed in the paper. The potential for reducing gaseous emissions is also an important chapter in this contribution. Complex calculations employing parameters of efficient use of limited resources and reduction of emissions seem to be helpful in finding optimums in production of food of animal origin.