Feed formulation is to point to by the optimal combination of the different feed ingredients to meet the needs for animal nutrition,For example in soybean meal, corn and other raw materials in certain proportion processed into feed for feeding pigs, ensure that pigs can grownormally.At the same time, because of the human society is an economic society, ensure the pig can normal growth is not enough, also need to do a lot of other requirements, such as grow faster, less money, large gains.Animal nutritional requirements in addition to the animal itself the growth and development of breeding needs energy, protein and other requirements, as well as in humans to their requirements, such as requiring a pig lean lean, so, the human must be artificially change animal nutritional requirements to achieve a certain purpose.