The use of feed antibiotics was once considered to be the greatest biotechnology in animal husbandry production in the 20th century. Its application and promotion created a revolution in the aquaculture and feed industries and contributed to the rapid economic development. But just as everything has two sides, with the long-term, high-level abuse of antibiotics, it has serious negative effects:
(1) Destroying the micro-ecological balance of the gastrointestinal tract of livestock and poultry, interfering with the immune system of livestock and poultry, especially the local non-specific immune system of the digestive system, respiratory system and reproductive system, reducing the resistance of livestock and poultry to diseases and affecting the health of livestock and poultry , seriously threatening the sustainable development of animal husbandry;
(2) Residue in animal products such as meat, eggs, milk, etc., directly threatening human health;
(3) Through the cross-inheritance and cross-propagation of antibiotic resistance, it interferes with the treatment of patients after infection and infected people with infectious diseases, and increases the dose of therapeutic drugs, which indirectly threatens human health.
When these problems appeared, countries around the world quickly took measures. Switzerland banned the use of antibiotics in 1992. Since January 1999, the EU has passed legislation prohibiting the use of antibiotics as growth promoters. The future development trend is to try not to use antibiotics. Since the 1980s, the world has spared no effort to research and develop its alternative products. In recent years, research on alternatives to feed antibiotics has been mainly beneficial to biotin (microbial preparations), oligosaccharides (chemical probiotics), Chinese herbal medicines, glycosides, enzyme preparations, acidulants and antimicrobial peptides.
1. Probiotics, also known as live bacterial preparations or microecological preparations (mainly Enterococcus, Lactobacillus, Bifidobacterium, Bacillus, Yeast, etc.), are non-toxic, no side effects, no residue green feed additives. Probiotics can proliferate in the digestive tract, produce lactic acid and acetic acid to lower the pH in the digestive tract, and produce metabolites such as lysozyme and hydrogen peroxide to inhibit the adhesion and reproduction of harmful bacteria in the intestinal mucosa, and balance the microflora in the digestive tract of animals. There is competition between survival and reproduction between probiotics and digestive flora, limiting the survival, reproduction and colonization and attachment of pathogenic bacteria in the digestive tract, helping the body to eliminate toxins and metabolites. Probiotics stimulate the body's immune system, increase the activity of interferons and macrophages, promote antibody production, and improve immunity and disease resistance. In addition, many probiotics have the effect of inhibiting the production of ammonia and other spoilage substances in the digestive tract. Probiotics produce a variety of digestive enzymes that promote the digestion and absorption of nutrients by animals.
At present, there are large amounts of lactobacilli, yeast and Bacillus subtilis in China. The product has a single strain of the dosage form, and most of them are complex dosage forms composed of various microorganisms. Probiotics are mainly used in young animals and have now developed probiotics for the poultry industry. It is used in poultry to prevent diarrhea, increase egg production rate and feed conversion rate, and has broad application prospects.
Most microorganisms are directly fed by living bacteria, which are easy to inactivate during production, transportation and storage, especially complex bacteria, some are anaerobic bacteria, some are aerobic bacteria, and it is still uncertain whether they can fully play their roles together; Some other feed additives cannot be used at the same time. For example, high copper ions have inhibitory activity on most probiotics; most bacteria cannot pass through the acidic environment in the digestive tract and cannot reach the destination - the intestine; the pathogen is dominant ( When the disease has broken out or is prevalent, probiotics cannot achieve the use of antibiotics.
2. Oligosaccharide oligosaccharides are a general term for oligomers having a linear or branched structure in which 2 to 10 glycosyl groups are linked by glycosidic bonds. There are many kinds of oligosaccharides, and the oligosaccharides currently used as feed additives mainly include: oligofructose, galactose, mannooligosaccharide, sucralose, soybean oligosaccharide, and oligo-isomaltose. These oligosaccharides are short-chain branched saccharides which are not digested by animals but can be utilized by intestinal beneficial microorganisms to promote the proliferation of beneficial flora. Oligosaccharides are similar to live bacterial preparations in that they regulate animal micro-ecological balance, which is called chemical probiotics in the nutrition community.
Oligosaccharides mainly maintain the established and healthy digestive flora in the body, selectively promoting the preferential reproduction of beneficial microorganisms in the digestive tract. Due to the specificity of the intermolecular binding position and the type of binding, oligosaccharides can not be decomposed by digestive enzymes secreted by monogastric animals, but can be used as nutrients in the later stages of the digestive tract as beneficial microorganisms such as bifidobacteria and lactobacilli. Streptococcus is digested and utilized, so that it can proliferate in a large amount, forming a micro-ecological competitive advantage. At the same time, the acidic substance produced by fermentation lowers the pH value of the whole intestine, directly inhibits the growth of the external bacteria and the inherent spoilage bacteria in the intestine, thereby exerting the normal intestine. The normal function of the flora in barrier, nutrition, and immunity. Certain oligosaccharides also have the ability to enhance immune and antigenic immune responses, thereby increasing animal humor and cellular immunity.
Oligosaccharide is a kind of indirect immune-enhancing substance. It has no bactericidal effect. It only provides nutrients for beneficial bacteria or provides targets for pathogenic bacteria. It can only help disease resistance and disease prevention. At the same time, oligosaccharides are easy to absorb moisture, which is not conducive to Store or evenly add; the cost is also relatively high.
3. With the residues, drug resistance and toxic side effects of synthetic drugs, antibiotics and other pharmaceutical additives , Chinese and Chinese herbal medicines have begun to find safer and more effective feed additives from Chinese herbal medicines. Chinese herbal medicine is a natural substance, safe and reliable, with few side effects. Because of its extensive antibacterial effect and synergy, it does not appear to be resistant, and overcomes the shortcomings of antibiotics. Some Chinese herbal medicines are rich in protein, vitamins and minerals, and have both pharmacological and nutritional functions.
The main functions of Chinese herbal medicine feed additives: (1) qi and digestion, spleen and stomach, such as dried tangerine peel, Divine Comedy, malt, medlar, hawthorn and so on. The aromatic flavor of these drugs can not only correct the taste of the feed, but also improve the palatability of the feed. After entering the gastrointestinal tract, it can also enhance the secretion of digestive juice. (2) promoting blood circulation and promoting metabolism, such as safflower, angelica, motherwort, spatholobus stem, etc., have the effect of directly or indirectly dilating blood vessels, strengthening blood circulation, and enhancing gastrointestinal function. (3) Detoxification, bactericidal and anti-disease, such as honeysuckle, forsythia, Jingsuke, Bupleurum, wild chrysanthemum, medical stone, etc. These Chinese herbal medicines have antibacterial and anti-inflammatory effects, which can both diarrhea and laxative pus. With these Chinese herbal medicine additives, it can prevent infectious diseases such as influenza and dysentery and protect animal health. (4) Deworming, such as betel nut, Guanzhong, Gentleman, Hundred, and sulfur, can eliminate the effects of insecticide and spleen. (5) Xuangan Huayu, relieving cough and asthma, such as Huashen, Niuhuang, Realgar, Atractylodes, Radix, Radix, Platycodon, Cicada, Barley, Strychnos, Borax and Baixu "Pills" has a significant effect on the treatment of infectious bronchitis in chickens.
Use Chinese herbal medicine to fry into soup or grind into fine powder to produce a single or compound preparation. Under normal feeding conditions, the preparation is added to the diet for animal feeding or drinking, in order to prevent animal diseases, accelerate growth, improve production performance and improve the quality of livestock and poultry products.
Not all Chinese herbal medicines meet the "green" standard. The compatibility and mechanism of some Chinese herbal medicines are still in the stage of exploration. Improper use can also cause residual and toxic side reactions. Because the functional ingredients of the compound Chinese herbal medicines are very complicated, some ingredients may be different. Feed additives have a negative effect, such as antagonism of probiotics, resulting in inactivation of enzyme preparations; general Chinese herbal medicine feed additives are relatively large in antibiotics and slow in effect; although people are very optimistic about Chinese herbal medicine feed additives, there is no quality of Chinese herbal medicine feed products. There is no fixed standard for the standard and Chinese herbal medicine formula. The product is rough and the quality test can be relied upon. Safety tests should be carried out before use to determine the effectiveness of the use and to avoid adverse consequences.
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