Antibiotics have played an important role in preventing livestock diseases, promoting animal growth and improving feed utilization. However, with the long-term use of antibiotics, their negative effects are increasingly exposed, such as causing pathogenic microorganisms to develop resistance and destroying normal animals. The ecological balance of the flora, the reduction of the immune function of the animal body and the harm caused by the drug residue to humans and the environment. With the development of animal husbandry and the improvement of people's living standards, people's awareness of food safety is gradually deepening. In addition, China has joined the WTO to strengthen the safety and greenness of feed industry products, and promote the popularization of safe and pollution-free green livestock and poultry products in China. It has become an important strategy for China's feed production enterprises to remain invincible in the fierce market competition. . In recent years, some antibiotic substitutes such as enzyme preparations, Chinese herbal medicines, probiotics, and oligosaccharides have been continuously developed. As a new green feed additive, glycosides are receiving more and more attention. Glycoside was developed by Professor Zhan Yong of Zhejiang University. In December 1999, it was certified by the National Green Development Center as the only AA natural green feed additive in the country. It has obtained 5 national invention patents. This article will review the application of glycosides in the production of pig industry.
1 Physicochemical properties and mechanism of action of glycosides
1.1 Composition and physicochemical properties of glycosides
Saccharin (SHP) is a natural extract of triterpenoids (≥30.0%) and sugars (total sugar ≥30.0%, of which polysaccharide ≥25.0%) extracted from the cakes of the Camellia plant seeds. It is a natural Biologically active substance. The finished product is brownish yellow, ashless and finely crystalline, and the taste is slightly bitter and spicy. It can stimulate the nasal mucosa and is easy to absorb moisture. It is insoluble in solvents such as ether, chloroform, acetone, benzene and petroleum ether. It is soluble in warm water, carbon disulfide and ethyl acetate. It is easily soluble in aqueous methanol, aqueous ethanol, n-butanol and glacial acetic acid. The glycosides can react colorily with acetic anhydride, ammonium molybdate, ferric chloride and vanillin, respectively. Glucosin has no antagonistic effect with Other feed additives, and there is no incompatibility.
1.2 Mechanism of action of glycosides
1.2.1 The role of oligosaccharides in glycosides
Oligosaccharide can be used as a nutrient for growth and metabolism, and is selectively fermented by Bifidobacterium and Lactobacillus, and promotes its growth and reproduction, and can not be utilized by Escherichia coli, Salmonella and Clostridium perfringens. Bifidobacteria and Lactobacillus produce lactic acid, acetic acid, butyric acid and propionic acid, which lowers the pH in the intestine, improves intestinal health, increases the solubility of calcium, magnesium, iron and copper ions, and promotes their absorption; The decrease of pH can also promote gastrointestinal motility, increase appetite, promote nutrient absorption and improve feed utilization; lower pH also inhibits the reproduction of harmful acid-free bacteria, thereby improving the intestinal environment and beneficial bacteria in the intestine. A large number of proliferation, in which bifidobacteria have a strong immune effect on the animal body (Tang Xiaoling, 2006). The cell wall of bifidobacteria contains a large amount of peptidoglycan and teichoic acid, which has strong biological activity and can activate the activity of peritoneal macrophages, NK cells and lymphocyte killing cells; bifidobacteria can also be used as a kind of The immune adjuvant stimulates the body to produce antibodies and slow down the release of antigen, prolonging the action time of the antigen; Bifidobacteria can also bind to cancer cells, have anti-tumor, eliminate free radicals and increase superoxide dismutase (SOD) activity. Role (Tang Xiaoling, 2007).
1.2.2 The role of triterpenoid saponins in glycosides
The main functions of triterpenoid saponins are: promoting antibody production, accelerating antigen-antibody reaction and lymphocyte transformation; increasing the function of animal macrophages, and enhancing the activity of deoxyribonucleic acid, saccharide acid phosphate and succinate dehydrogenase in cells. Saponins have a wide-ranging effect on enhancing humoral immunity, cellular immunity and immunomodulation; can promote the synthesis of nucleic acids and proteins, regulate blood sugar, reduce cholesterol in high cholesterol animals, and promote lipid synthesis in normal animals; By regulating glucocorticoid levels, regulating enzyme activity, stimulating glycogen synthesis to lower blood glucose levels; significantly enhancing and inducing SOD and glutathione peroxidase (GSH-Px) activity; enhancing macrophage secretion of tumor necrosis factor; Antibacterial, anti-inflammatory and anti-mutagenic effects; CN3 in triterpenoids is a promoting factor for protein synthesis, and can calm the spirit, relax muscles and cool down, and inhibit the growth of cancer cells (Shen Weiwu, 2009).
2 Toxicological test of glycosides
Li Dingmei (2000) showed that acute toxicity: mouse LD50=2 378.48mg/kg, rat LD50=3 921.93mg/kg; mouse accumulation toxicity: K value is 6.6373, is a weak accumulation of poison; mutagenicity test: small Rat micronucleus, sperm aberration and Ames test were negative; teratogenic test: subchronic test proved no teratogenicity. In summary, the use of glycosides is safe.
3 Application effect of glycosides in pig production
3.1 glycosides can improve diarrhea in weaned piglets
Li Defa et al. (1996) reported that one of the main causes of diarrhea in weaned piglets is that Escherichia coli uses ammonia and protein in the intestine to produce ammonia, which stimulates the intestinal mucosa, causes endotoxin and exotoxin secreted by the intestinal tract to be absorbed, and intestinal osmotic pressure. Increased, osmotic pressure occurred in diarrhea. Glucosin can promote the proliferation of bifidobacteria and lactobacilli, produce a large amount of organic acids, increase protease activity, promote protein digestion and absorption of amino acid nutrients, inhibit the proliferation of E. coli, and reduce the spoilage of crude protein in the large intestine. Thereby reducing the ammonia content in the intestinal tract of piglets and reducing the diarrhea rate of piglets. Wu Qiuqi et al (2008) showed that the addition of 0.05% glycosides to the diet of early weaned pigs significantly increased the daily weight gain of weaned pigs (P<0.05) and the diarrhea rate significantly decreased (P<0.05).
3.2 glycosides can improve pig growth performance
The function of the animal's digestive system is directly related to feed conversion and animal growth. Oligosaccharides are beneficial to the proliferation of beneficial bacteria such as bifidobacteria and lactobacilli, and lower the pH value in the intestine, thereby facilitating the absorption of nutrients and improving the growth and development of pigs. Liu Changzhong et al (2002) found that the daily average weight gain of 500mg/kg glycosides was 1.9% higher than that of the 150mg/kg oxytetracycline group, and the feed-to-meat ratio was reduced by 6%. Lu Guoquan (2002) added glycyrrhizin 400mg/kg to the diet of early weaned piglets. The results showed that the daily gain and feed-to-meat ratio were significantly different from the control group (P<0.05), and the economic benefit was 14% higher than that of the control group. Wang Yuanzhen (2009) showed that the addition of 400 mg/kg of glycosides to the diet of weaned piglets increased the daily weight gain of piglets by 7.10% (P<0.05); the ratio of feed to meat decreased by 4.63%; and the mortality decreased by 6.67%.
3.3 glycosides can improve immune and antiviral function in pigs
Glucosin can induce immune cells in the body to produce interferon, tumor necrosis factor and interleukin-2 and other cytokines, enhance non-specific immune function; increase immunoglobulin content, promote antibody formation, enhance specific immune function; increase T lymph Cell transformation rate, enhance cellular immune function; promote immune organ development and enhance disease resistance. Glucosin enhances immunity by enhancing the body's own immune function, thereby achieving antiviral effects. Professor Zhan Yong of Zhejiang University added 250,500mg/kg of glycosides to the piglet diet. The total number of T lymphocytes in serum increased by 5.32% and 30.15%, respectively (P<0.01), and the IgM content increased by 43.21% (P< 0.05) and 104.89% (P < 0.01). In addition, the addition of 500mg/kg of glycosides, the antibody titer of the swine fever is 40% higher than that of the added xanthine polysaccharide, and it can be seen that the glycosides have a significant effect on the antibody titer of the swine fever.
3.4 glycosides improve pork quality
Generally, the meat-improving additives include vitamins C, D, E and mineral elements such as calcium, magnesium, selenium and chromium, and glycosides also have the effect of purifying the internal environment and improving the meat quality. By promoting the metabolism of livestock and poultry and strengthening the circulation of body fluids, glycosides help to purify the liver environment, accelerate the proliferation of liver cells, enhance the vitality and detoxification of liver cells, and help remove free radicals and heavy metal elements. The active substance trisaponin in glycosides has anti-oxidation function, which can delay the aging rate of body cells, reduce the oxidation of fat in the body and the synthesis of cholesterol, increase the content of polyunsaturated fatty acids in livestock and poultry products, thereby improving livestock and poultry. The quality and flavor of the product. Zhan Yong et al. (2005) showed that adding 500mg/kg of glycosides to finishing pig diets can improve the color of the meat, lower the cholesterol content, and increase the inosinic acid content, thus improving the meat quality.
3.5 glycosides can remove free radicals from pigs and strengthen the body's antioxidant effects
Studies have found that many diseases, such as cancer, aging and arteriosclerosis, are related to the toxic reaction of oxygen free radicals. Oxygen free radicals react with biological macromolecules such as DNA, resulting in the destruction of cell structure and function. The active substance saponin in glycosides can scavenge superoxide radicals, hydroxyl radicals and lipid free radicals, reduce the formation of free fatty acids and slow the initiation of auto-oxidation of fat, and the efficiency of free radical scavenging increases with the concentration of glycosides. improve. In addition, saponins in glycosides can also be combined with heavy metal ions such as Fe2+, Cu2+, Pb2+, etc. to improve the antioxidant function of the body.
3.6 glycosides can improve the anti-stress effect of pigs
Stress is a non-specific immune response of an animal to various external or internal stimulating factors. Stress can cause animal growth to stagnate, weight loss, feed conversion rate and increase disease susceptibility, reduce vaccination effect, PSE meat / DFD meat. The bioactive substance triterpenoids contained in glycosides has the effects of calming, relieving pain, antipyretic, antitussive and anti-inflammatory. It may regulate the balance of the environment in the body, reduce the body's sensitivity to stress, and cooperate with the immune regulation to relieve The immunosuppression produced by stress increases the anti-stress ability of animals.
4 Suitable dosage of glycosides in pig production
Glycoside can be used clinically to prevent viral diseases such as Newcastle disease, swine fever, and blue ear disease. According to comprehensive research, the suitable addition amount of glycosides in each 1000kg compound feed is: 400-600g for suckling pigs, 400-600g for piglets, 300-500g for medium pigs, 200-400g for large pigs, 200-400g for pregnant sows, breastfeeding The sows are 300 to 500 g.
5 Application prospects of glycosides
The active ingredient of glycosides is stable in performance and safe to use. It has no compatibility contraindications with other feed additives and drugs. Its promotion and application will promote the green process of China's feed industry, eliminate the adverse effects brought by antibiotics, implement a healthy breeding system, and accelerate animal products. Exports earn foreign exchange and maintain the healthy and healthy development of animal husbandry.
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