Animal nutrition focuses on the dietary nutrients wants of animals, primarily those in agriculture and food production, however conjointly in zoos, aquariums, and life management. There are seven major categories of nutrients: carbohydrates, fats, fiber, minerals, proteins, vitamins, and water. Macronutrients (excluding fiber and water) offer structural material (amino acids from that proteins are designed, and lipids from that cell membranes and a few signaling molecules are built) and energy. A number of the structural material may be accustomed generate energy internally, although information superhighway energy depends on such factors as absorption and organic process effort, that very well from instance to instance. Vitamins, minerals, fiber, and water don't offer energy, however are needed for different reasons. A 3rd category dietary material, fiber (i.e. non-digestible material like cellulose), looks conjointly to be needed, for each mechanical and organic chemistry reasons, although the precise reasons stay unclear.