In recent years, people have developed antibiotic substitutes such as feed enzyme preparation, feed microbial preparation, acidifier, antimicrobial peptide, oligosaccharide, allicin, Chinese herbal medicine and organic metal trace elements. These green feed additives are favored by people.
Enzyme preparation
Since the establishment of the first enzyme preparation factory in Wuxi in 1965, after more than 40 years of efforts, the products of enzyme preparation in China have been increasing continuously and the quality has been improved continuously. At present, hundreds of products, such as alpha-amylase, beta-amylase, protease, lipase, cellulase, pectinase, beta-glucanase, mannase and phytase, have been developed. . At present, the most commonly used enzyme feed additives are divided into two categories: one is mainly to degrade polysaccharides and biomacromolecules, mainly including protease, lipase, amylase, glucoamylase, cellulase, xylanase, mannanase. Its main function is to destroy the plant cell wall (plant cell wall by protein, fat, polysaccharide blue bond linked into a network structure), so that the content of the cell is fully released. The other is mainly phytase, beta-glucanase, pectinase and other anti-nutritional factors, including phytase, beta-glucanase, pectinase. It can degrade cell wall xylan and intercellular pectin components, and improve feed utilization. Enhanced carbohydrate enzymes include digestion of non-starch polysaccharides, increased utilization of soybean or other plant proteins by proteases, enhanced lipase degradation and utilization of lipids, and enhanced phosphorus and other mineral elements digestion and absorption by phytase. The theoretical value of mannan was 0.42% in broiler feed prepared with 30% soybean meal and 60% corn, which could reduce the feed utilization rate by 7.5%. Using mannan enzyme, feed conversion efficiency can be increased by 7.7% and cost savings by 10%.
Microbial preparations for feeding
Probiotics are beneficial in vivo microbial preparations (DFM) or live or microbial agents that can be fed directly to animals. In 1989, the Food and Drug Administration (FDA) and the Association of Feed Control Officials published 40 safe and effective microbial strains.
Lactobacillus preparation Lactobacillus acidophilus, Bifidobacterium Lactobacillus and Streptococcus faecalis. Lactic acid bacteria can survive under the condition of pH3.0 or 4.5 acid under the condition of micro aerobic or anaerobic. It can decompose sugar to produce lactic acid. Acidoline can effectively inhibit the growth of E. coli and Salmonella, but it is not heat-resistant, and dies at 65 ~75 ~C.
Bacillus preparations include Lichenella, Bacillus subtilis, Bacillus cereus, Bacillus orientalis, which belong to aerobic Bacillus and sporadically exist in the intestinal microbial community of animals. When applied, the bacteria preparation for dormancy of the bacterium is made or mixed with lactic acid bacteria. The product has many advantages: acid resistance, salt resistance, high temperature resistance (100 C) and extrusion resistance, stability; can produce protease, lipase, amylase.
Fungi and live yeast preparations are commonly used in two products, Aspergillus oryzae and Saccharomyces cerevisiae culture, they include fungi and their cultures, mostly used in ruminants. Its main characteristics are aerobic, like to grow in the environment of polysaccharides, acid; and its body is rich in protein and a variety of B vitamins, but not heat-resistant.
The main functions of probiotics are to maintain the balance of intestinal microecology. Probiotics can produce hydrolytic enzymes, fermentative enzymes and respiratory enzymes, anti-pollution effects of probiotics, and immune regulation of probiotics.
Acidifying agent
Acidifying agents can be divided into organic acids and inorganic acids. Organic acids are mainly citric acid, fumaric acid and so on, and commonly used inorganic acids are phosphoric acid. Animal stomach is acidic environment, in which most of the bacteria are acid-producing bacteria and acid-tolerant bacteria. Juvenile animals have weak ability to secrete gastric acid, making exotic bacteria easy to survive and reproduce. Acidifiers can improve the acidity of gastric juice, promote the proliferation of acid-tolerant bacteria such as lactic acid bacteria, so that they can maintain the dominant position in the stomach, while E. coli and other foreign bacteria can not adapt to the acidic environment, and by lactic acid bacteria and other "exclusion" and can not survive, thus reducing the incidence of animal pathological diarrhea. Acidifying agents can also help the body adjust the immune system response and enhance the disease resistance of animals.
Organic acids can improve the digestion process, especially for mono * stomach animals, and the effect of poultry is not obvious. During digestion, proteins and carbohydrates need to consume H+ continuously in digestion of proteins and carbohydrates. The use of organic acids can reduce intestinal pH, affect the replication of microbial DNA, and inhibit the formation of harmful microorganisms in the anterior part of the digestive tract. Planting. The addition of organic and inorganic acids to feed can be used as a way to protect animal health without antibiotics. Acidifiers directly stimulate oral taste bud cells, increase saliva secretion, promote appetite, improve protein digestibility and protein deposition, is conducive to the absorption of trace elements, enhance the ability to resist disease. The addition of organic acids can increase the acidity of immature digestive tract, activate some important digestive enzymes and facilitate the digestion of nutrients. Acidified diet can inhibit or prevent the colonization and reproduction of E. coli or other harmful microorganisms in the intestine, prevent the occurrence of intestinal diseases, and improve the ability of animals to resist stress.
Antibacterial peptide
Antimicrobial peptides mainly include cecropin, magainin, defensin and Tachvplesin. Antimicrobial peptides not only have broad-spectrum antibacterial effect, but also can act on a few prokaryotes and viruses, and have no (or very small) physiological damage to human body, other animals and plants; bacteria are difficult to produce resistance to them. So antibacterial peptides