Feed is not veterinary medicine, relying on a "classic" formula to solve all the problems is not realistic, to invariable should change the feed formula cannot be perfect. The quality and price of feed raw materials are constantly changing; Feeding and management methods are different; Piglets vary in breed, stage of development, state of health and environment. The genetic performance of pigs is improved every year, and the nutritional requirements are also changed. Special circumstances, such as seasonal changes, or the occurrence of certain infectious diseases and nutritional metabolic diseases, should be appropriate to adjust the proportion of relevant raw materials in the feed formula or the level of a certain nutritional indicator.

It is the work of the researcher to design the feed formula out of the market, not the product target of the commercial feed. The purpose of timely adjustment of feed formula is to make the designed feed formula can be prepared to meet the needs in nutrition, in the aspect of low price, and palatability and digestive utilization ratio are good compound feed.

Feed is the carrier of various nutrients. Whether the feed formula can achieve the design goal of the key lies in: (1) the understanding of animal nutrition needs is accurate; (2) The accuracy of the available nutrient content or biological titer of feed raw materials; (3) Accurate prediction of nutrient loss during the processing and storage of compound feed; Feed formula design technology. So these are the primary goals of nutrition, forage, and formulators.