Analysis and control of safety hazards of feed trace elements.

micronutrient nutrition is the cutting-edge research field of animal farming and formulation technology. For many years is to provide trace element nutrition with traditional inorganic salt, but with the deepening of research, the traditional inorganic salt in the production and use of the process of a greater safety risk, resulting in the quality of animal products and environmental pollution problems, more and more people's concern and attention. The research and selection of new trace element additive products with safety, stability, efficiency and environmental protection has become the focus of increasing attention in the industry.
xXL .As a nutrient essential to animals, trace elements are involved in a series of physiological and biochemical reactions in the body in the form of essential components of enzymes (coenzymes, coenzymes, etc.) or activators, and are regulating the encoding of various proteins, such as enzymes, carriers, receptors, and biological structures. The genes of the ingredients play a very important role, thus affecting the metabolism and growth and development of nutrients in animals, according to its physiological function applied to the production of the actual production to meet the basic nutritional needs of the animals to trace elements, and can effectively improve the production performance of animals, for animal reproduction, immunity, growth and development and other physiological mechanisms necessary. At present, at home and abroad in animal breeding often used in the trace elements are many, commonly used trace elements are copper, iron, zinc, manganese, selenium, iodine, drilling, potassium, sodium, aluminum and so on. Although the amount of dosage is not much, the problems of animal product quality and environmental pollution caused by this are becoming more and more serious, which is attracting more and more people's attention and attention. Although the traditional inorganic salt products have a long history of use, but in the production, use of the process of quality and safety accidents also occur from time to time.
xXL .1 Commonly used trace elements of the safety hazards
xXL1.1 zinc source
xXLzinc can promote animal growth, affect bone development, enhance animal immune function, improve the appearance of fur, affect the taste and appetite of animals, known as "life elements." At present, the commonly used zinc source products in the market are zinc sulfate, zinc oxide, zinc protein salt, alkali zinc chloride, amino acid chelate zinc, etc.
xXL .1. 1. 1 Heavy metals, impurities high content affect the use of products
xXLin nature, zinc, lead, cadmium, copper is a symbiotic mine, cadmium and zinc are the same elements, zinc sources often cadmium pollution. Zinc sulfate is used as raw material for sub-zinc oxide (the main components are zinc, iron, copper, lead and cadmium and trace amounts of arsenic), and copper cadmium residue (the main components are zinc, copper, cadmium). If the quality of industrial sulfuric acid used is uneven, it will lead to cadmium in the product, lead content is greatly exceeded, of which cadmium content variation range is the largest. Excessive cadmium contaminated feed products by zinc source, animals after harvesting cadmium poisoning, so that the amount of food reduced, production performance reduced. Affected by the production process, feed-grade zinc oxide impurity content is more than 2-8%, the main impurities are iron oxide, resulting in inconsistent product appearance color, while the lead containing, cadmium often exceeds the standard, lead content can be as high as 100 mg / kg, cadmium up to 6%, animal health and growth is extremely unfavorable; Zinc content is also volatile, with significant changes in relative biological efficacy, ranging from 35% to 70%. In recent years, the test results of the National Feed Quality Supervision and Inspection Center (Wuhan) also showed that: zinc sulfate samples of cadmium content exceeded the standard of 10.3%, zinc oxide samples of cadmium content exceeded the standard of 15.1%, the highest content of 2.92%. Lead content exceeded 1.7%, total arsenic content exceeded 0.9%, if the use of such a zinc source, not only the cadmium content in the feed will exceed the standard, product quality does not meet the feed hygiene standards;
xXL .1.1.2 Oxidant residue, affecting the quality of feed productstability
xXLin the production process of zinc sulfate, often use potassium permanganate, hydrogen peroxide or bleach ingenuitious agents to remove iron, cadmium and other impurities, if not treated well, there will inevitably be oxidant residue, mixed into the premix with vitamins (choline, VC, VA), iron, oil chemical reaction, and because of the iron oxide.
xXL .1.1.3 Pollution of zinc protein salts
xXLproduction of zinc protein salts are mostly animal protein products or plant protein raw materials such as animal hair or leather underfoot materials. These raw materials are easily contaminated by pathogenic microorganisms, cadmium, melamine, non-protein nitrogen and so on, in addition to plant proteins phytic acid, non-starch polysaccharides and so on are very easy to combine with zinc, this kind of zinc can not be used by animals, seriously affecting the relative biological price of zinc. In addition, a mixture of protein powder and inorganic trace elements is also available on the market as an organic argon compound product.
xXL .　　1.1.4 The way to solve the problem
xXL At present, many enterprises in the purchase of bulk raw materials strictly quality control, and zinc sulfate, zinc oxide and other small materials due to lack of testing equipment, it is difficult to control its quality. Because of the supply of such raw materials manufacturers, zinc sources of harmful substances such as cadmium, lead and other more common, such as accidental purchase will lead to the product of harmful substances content exceeded the standard, affecting the stability of product quality. For example, Guangxi has an annual output of 60,000 pigs pig farm, because of the use of cadmium, lead super-standard trace element additives, the emergence of a large-scale pig carcass muscle whitening phenomenon, causing serious economic losses.
xXL .　　In addition, due to the production process of zinc sulfate, the content of residual free chloride ions in the product is high, resulting in easy moisture absorption and clumping of products, shortening the shelf life of the product, which has an adverse effect on feed production.
xXL .　　In view of the many problems in the production and use of traditional inorganic salt products, new zinc source products such as zinc chloride, zinc glycine, methionine zinc, hydroxy methionine zinc, lysine zinc and so on emerged.
xXL .　　Alkaline zinc chloride is produced through a special process synthesis, in the production process does not use traditional oxidants (such as potassium permanganate, hydrogen peroxide, hypochlorite, etc.) in addition to miscellaneous, the production of products without oxidant residues, can effectively avoid the addition to the mineral premixed feed produced by the phenomenon of discoloration; Because of its good stability, not easy to dissolve in alkaline solution, only in the acidic stomach dissolved part, more to the molecular state into the intestine sway, but also because of its convergence and adsorption effect, can converge intestinal epithelial cells, reduce intestinal mucosal permeability, reduce the intestinal cell fluid leakage, improve feces dryness, prolong feces in the intestines when asking, to prevent pig diarrhea. As a new source of zinc, with pro-growth and after use will not lead to the later growth inhibition of pigs and affect the appearance of fur, especially the improvement rate of feed conversion can reach 3%-5%, and may even be higher, production and economic benefits are obvious.
xXL .　　Glycine zinc, methionine zinc, hydroxy methionine zinc, lysine zinc and other relatively stable chemical structure, can prevent zinc and feed phytic acid, phosphate root ions, etc. binding, but also to prevent animal digestive tract insoluble alysone adsorption, but also effectively resist the formation of insoluble with other ions Inorganic salts, to alleviate mineral antagonic competition, in vitro to reduce the destruction of vitamins by metal ion redox reaction, thereby reducing the loss of nutrients, increase the degree of their absorption and utilization, can improve the storage stability of vitamins in compound premixes, significantly reduce the rate of vitamin loss in premixes.
xXL .　　1.2 Copper source
xXL copper is one of the important trace elements needed by animal body, which plays an important role in the body's blood production, growth and reproduction, and enhances the body's resistance. At present, the copper sources used by feed enterprises are mainly copper sulfate, alkaline copper chloride, amino acid chelation copper and so on.
xXL .　　1.2.1 Copper sulfate stability is poor
xXL copper sulfate is a very water-soluble acid compound, easy to absorb moisture decomposition, resulting in clumps, added to the use of difficulties, and the processing of production equipment caused serious corrosion damage.
xXL .　　1.2.2 Copper sulfate has an oxidizing effect, so that the product shelf life is shortened
xXL copper sulfate moisture after the first is to make the feed easy to clump, followed by the decomposition of the moisture to produce copper cation and sulfate ions, thus providing electrical transfer of "the " Hot spots", accelerate the oxidation and destruction of nutrients in the feed, such as vitamin destruction and oil acidity, but also reduce the biological price of copper;
xXL .　　1.2.3 The use of high-dose copper sulfate can easily cause environmental pollution
xXL use high doses of copper sulfate to play a role in promoting growth and inhibition, in addition to animal absorption part, most of the copper excreted from the body, the damage to the environment, pollution of soil and water, another part of copper deposited in the liver of animals, human consumption is very easy to cause copper deposition and poisoning. Therefore, the Ministry of Agriculture announced No. 1224 "Safe Use Of Feed Additives Regulation" provides for the highest limit of copper in the matching feed or fully mixed diet.
xXL .　　1.2.4 The use of high doses of copper sulfate easily leads to the occurrence of yellow meat
xXL recently, the main reason is the use of high copper and improper selection of copper source, a large number of VE is highly oxidized copper sulfate damage, while the free copper ions produced in the feed easily make oils, especially unsaturated fatty acids oxidized, metamorphic acid.
xXL .　　1.2.5 The solution to the problem
xXL low-content copper sulfate has no obvious effect on increasing daily weight gain, feeding volume and feed efficiency. The use of alkaline copper chloride, amino acid co-copper can effectively improve daily weight gain, food harvest, improve feed remuneration under the premise of the same content.
xXL .　　The amino acid chelating copper is made up of a specific amino acid separated from copper in a ratio of 1:1 or 2:1 moles. Experiments show that the amino acid candor copper has a more stable chemical structure, the use of amino acid co-copper can effectively improve the content of copper in livestock and poultry tissue, and participate in the production of a variety of enzymes, activation, enhance the animal body's immunity and anti-stress ability, can be rapidly absorbed by the intestine, reduce the trace elements of the problem of antagonization, can promote animal growth, improve feed remuneration. However, due to the production of raw materials and process requirements, its production costs are also high, so only suitable for use in certain high-grade materials.
xXL .　　Alkaline copper chloride products are chemically similar to amino acid-like neutral compounds, with gender free and other electrical points, similar so on chemical properties such as solubility. This alkali salt is insoluble in water but easily dissolves in the animal's gastrointestinal tract rather than dissoced, and exists in the gastrointestinal environment in the form of a large number of compound molecular groups, with no competitive inhibitory effect on other trace elements. In the intestine in the form of molecular groups to stimulate small intestine fluff epithelial cells, stimulate the production of hormones, play a pharmacological role similar to antibiotic sepsis, can improve animal production performance, high conversion rate;
xXL .　　1.3 Iron source
xXL iron is one of the essential trace elements of animals, is the composition of most metabolic enzymes in animal sin, but also hemoglobin, myoglobin, lactoferrin and other proteins an important component. In addition, iron, as a component of cytochrome, is involved in the energy metabolism process escticia of animal cells. The iron sources in the feed are mainly iron sulfate, amino acid tantalum iron, fumaatinic iron and so on. Due to the instability of iron ions, in feed, divalent iron is easily oxidized into trivalent iron and loses its nutritional function. The absorption rate of iron sulphate is only 3%-10%, in order to achieve the desired feeding effect, usually add excessive iron sulfate, however, excess iron sulfate will affect the digestion and absorption of other trace elements, and oxidation and destruction of vitamins;
xXL .　　From the production process, the raw material of the production of iron sulfate is basically the production of titanium dioxide by-products, general processing enterprises using wet production of products easy to clump, high impurity content, easy to residual in the form of titanium sulfate titanium compounds, the oxide has a strong oxidation, the redder of the color, Fe3 plus residues, and other nutrients have oxidation and destruction effect, thus affecting the quality of feed products. And the current standard sisped without a limit of titanium, the production enterprises have no control over this, the quality supervision department can not supervise the inspection.
xXL .　　The amino acid argon iron as an iron supplement, mainly glycine iron, hydroxy methionine iron, methionine iron, etc., can fully meet the nutritional requirements of livestock and poultry on iron;