The general term for all kinds of hormones that can regulate and control the endocrine mechanism of animals, so that the nutrients entering the body can be redistributed in a beneficial direction according to human needs for animal growth. Hormones only regulate (increase or decrease) the speed of certain physiological reactions, but they cannot provide the energy for the reaction process itself, nor can they initiate new metabolic reactions. Therefore, when the original response is excessively stimulated, it is as harmful as when the hormone is deficient. In the past, thiouracil, iodinated protein, and estradiol were used as feed growth hormone for additives, but it was soon found to have side effects and was banned. The growth hormone currently used as a feed additive, with a molecular weight of about 22000, is a pituitary hormone. It is a single-chain polypeptide molecule composed of 191 amino acids in a certain order and can be extracted from the pituitary. It can also be produced by recombinant DNA technology. Growth hormone acts on the entire body, and it has effects on protein synthesis, glucose metabolism, regulating renal function (glomerular filtration rate) and water metabolism, and increasing the permeability of cells to amino acids, so it can promote the body (bone, muscle and Organs). This hormone has interspecific specificity. The growth hormone present in cattle is only effective for cattle. It is not only used to promote growth but also has adverse effects. When taken orally, this hormone is destroyed by digestive enzymes, which breaks down into amino acids and becomes ineffective. Often the entire protein molecule is not used, but as long as 38 to 40 amino acid fragments, even smaller peptides are active, they can promote the growth of young animals and prevent dwarfism caused by small growth hormone secretion; for animals with raw milk tissue May increase lactation. In addition, research on growth hormone for pigs has also progressed. Injection into piglets can promote growth and increase lean meat. The mechanism of action of hormones is very different from that of general feed additives. Therefore, it is difficult to judge the overall advantages and disadvantages of general feeding tests and metabolic tests, and it needs to be comprehensively evaluated from the perspective of endocrinology, toxicology and even genetics. In addition, countries and regions with tight protein resources should also consider their nutritional resource background and actual economic effects. Under low nutrient levels, growth hormone often has difficulty obtaining the expected results.