Trace elements are one of the essential nutrients for maintaining animal life and growth. They directly or indirectly participate in many important physiological and biochemical processes of the body to meet the normal life activities of the body. With the advancement of science and technology and the enhancement of people's health awareness, people are paying more and more attention to the quality and safety of animal products while pursuing high animal yields. They are also paying more and more attention to the environmental pollution caused by the use of high-dose inorganic substances. Organic trace elements have provided an effective solution to the problem of high-dose trace elements contamination after three stages of inorganic salts, simple organic compounds and amino acid complexes. The amino acid trace element complex overcomes the disadvantages of low absorption and utilization rate of inorganic salt and simple organic matter, unstable effect and poor palatability, and has good stability, good palatability, high absorption and utilization rate, good fluidity and can be alleviated in the feed. The advantage of the destruction of nutrients is a green feed additive that integrates safety, efficiency and environmental protection. Since the 1980s, China has been developing organic trace elements. After more than 20 years of development, the research and promotion of organic trace elements has reached a new level, and the scope of application has gradually expanded from livestock and poultry production to aquatic products. 1 The advantages of organic trace elements as aquaculture feed additives 1.1 has a higher absorption rate and biological activity Inorganic salts and trace elements in the form of simple organic substances enter the intestinal tract of aquatic animals. Metal ions need to form a complex with the carrier molecules in order to pass through the intestinal mucosa and enter the blood, which is then transported by blood to various tissues of the body. The amino acid trace element complex is a low molecular weight ligand form of trace elements. It is not only the main form of the body's absorption of metal ions, but also an intermediate substance in the process of synthesizing proteins in animals. After entering the aquatic animal, it is different. The amino acid needs of the tissue and enzyme system transport the trace elements complexed by amino acids directly to specific target tissues and enzyme systems, and release trace elements through the action of enzymes and tissues to meet the needs of the body. This is much faster than the absorption of inorganic trace elements, which can promote the rapid absorption and utilization of amino acid trace element complexes in the body. According to the research of scientific research departments at home and abroad, the absorption rate of amino acid trace element chelate in aquatic animals is 1.25~2.5 times that of inorganic salt, which has larger and superior general absorption and digestion and metabolism than inorganic salt. The absorption rate of amino acid chelated copper is 1.5 times larger than that of carbonate, 2.25 times larger than sulfate, and 1.25 times larger than oxide. The absorption rate of amino acid chelated magnesium is 1.8 times larger than that of carbonate and 2.5 times larger than sulfate. The absorption rate of amino acid chelated iron is 1.5 times larger than that of carbonate, 1.8 times larger than sulfate, and 2.5 times larger than oxide. Amino chelated zinc is 2.1 times larger than sulfate and 2.5 times larger than oxide. 1.2 good stability, to avoid the destruction of nutrients in the feed of metal elements The metal element ions such as Fe2+, Cu2+ and Mn2+ in aquatic animal feeds easily form phytic acid trace element complexes with phytic acid at pH 5~6, and the stability constant is 10.85~17.63, which is difficult to be digested, absorbed and utilized by aquatic animals. The amino acid trace element chelate is centered on the metal ion, and the amino acid acts as a ligand. The metal central ion can be ionically bonded to the carboxyl group in the amino acid molecule, and can also be coordinated with the amino group in the same amino acid molecule. Combined, it constitutes a five-membered ring or a six-membered ring structure, which is relatively stable. Because of its unique ring structure and high chemical stability, its intramolecular charge tends to be neutral, which can effectively avoid the influence of phytic acid in aquatic feed and reduce the enthalpy effect of some metal trace elements and Ca2+. To improve its utilization. Metal element ions such as Fe2+, Cu2+ and Mn2+ in aquatic feed can directly cause rapid decomposition and deactivation of vitamins, especially vitamin A, pantothenic acid, vitamin C and vitamin E. The crystallization of water in inorganic trace elements and the moisture in the additives also accelerates the destruction and decomposition of trace elements. The use of organic trace elements (amino acid chelates) can, to a certain extent, ensure the nutritional integrity of the feed and reduce costs. Marchetti and other research pointed out that vitamin A, vitamin D3, vitamin E, vitamin K, vitamin B1, riboflavin, vitamin B6, vitamin B12, vitamin C, niacin, pantothenic acid, folic acid and biotin and Cu, Zn, Fe, respectively After mixing the sulphate of Mn and Co and its amino acid chelate, the two mixtures are equally divided into two parts, one part is stored at 37.3 ° C, and the other part is stored at 20.3 ° C, at 0, 90 and 180 d. Determination of vitamin content, the results showed that vitamin B6, riboflavin and vitamin A, vitamin C and vitamin K in the sulfate mixture at 20.3 ° C significantly reduced in the sulfate mixture, but in the amino acid trace element chelate Almost no less. It shows that amino acid trace element chelate can reduce the oxidation of vitamins when coexisting with vitamins. 1.3 low toxicity, good palatability Because the bioavailability of inorganic salts is relatively low, in order to meet the demand for trace elements in aquatic animals, a large amount of inorganic salts are generally added to aquatic feeds, and undigested inorganic ions are largely discharged into water bodies. It can cause pollution to water bodies. When the concentration of Fe2+, Cu2+ and Mn2+ in water reaches a certain concentration, it will have certain effects on the respiratory system, respiratory movement, growth, immunity and embryo development of aquatic animals. The organic micro-element has high absorption and utilization rate and stable structure, and is an effective method for solving environmental pollution caused by excessive use of trace elements. The general inorganic trace elements have poor palatability and bitter taste, while the amino acid chelated trace elements have the unique sweetness of amino acids, have good palatability, and have good attracting effects on fish and shrimp. 1.4 Adjusting the immunity of aquatic animals and improving their resistance to disease and stress The amino acid trace element chelate is structurally similar to the form of enzymes in animals, such as copper and lysine, cysteine ​​and tryptophan. It has cytochrome reductase activity, can improve humoral immunity and cellular immunity, enhance bactericidal ability, improve its resistance to disease and stress, and thus improve production performance. At the same time, trace element amino acid chelate can also reduce the formation of free radicals in the body, enhance the bactericidal ability, improve the immune response level of the animal body, and have significant therapeutic effects on certain enteritis, skin diseases and anemia. 1.5 Forming a Buffer System, Regulating the pH of the Intestines The reaction of metal ions and organic ligands provides a buffer system for the mass concentration of metal ions in the medium, which ensures a constant mass concentration of metal ions by dissociation or synthesis of the chelate. The body can control the level of free metal ions in the buffer system by controlling the pH level in the intestines and tissues, so that the body can be provided with a metal ion storage pool that can be used in the animal. A concentration level that is required but not toxic. Inorganic salts can affect the pH in the gastrointestinal tract and the acid-base balance in the body. The amino acid chelate is a normal intermediate in the body, which rarely causes adverse stimulation to the body, and is beneficial to animal feeding and digestion and absorption of the gastrointestinal tract. 2 application of organic trace elements in aquatic animals 2.1 Application of organic trace elements in fish farming 2.1.1 growth-promoting effect Organic trace elements can provide a variety of amino acids and trace elements for the growth and reproduction of animals. This substance is most beneficial to the replication, activation and regeneration of enzymes in animals, and has obvious growth-promoting effects on fish growth. Studies have shown that when the quality is taken as an indicator, the bioavailability of channel catfish to zinc methionine is equivalent to 352% of the bioavailability of zinc sulfate. Zhang Chun also got a similar result: adding organic zinc (zinc lactate) to the carp feed can reduce the amount of zinc without reducing the growth performance of the carp. Li Aijie et al pointed out that the tilapia was fed with amino acid trace element chelate (Fe, Cu, Mn, Zn and Co), and the weight gain rate of tilapia in the amino acid chelate salt group was 17.84%~25.84% higher than that in the inorganic salt group. The feeding experiment on carp showed that the quality of the three experimental groups with the addition of amino acid trace element chelate was 37.2%~68.1% higher than that of the control group. Zhao Yuanfeng et al. compared the tilapia with amino acid trace element chelate and inorganic salt additive. The results showed that the growth of tilapia with trace element amino acid chelate was significantly better than that of inorganic salt group, and the four experimental groups were better than the control group. Increased quality by 75.7%, 86.5%, 108.5% and 89.0%. 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