Application of microbial feed additives in aquaculture

(Heilongjiang Province 853 Farm Feed Factory. Baoqing.155630)
Microbial feed additive is a live microbe additive that affects animals by improving the balance of intestinal microflora in livestock and poultry. It is based on in-depth research on intestinal microecology and a new generation of antibiotics developed using modern biotechnology. product. In foreign countries, research and development began in the early 1960s. At present, Japan, the United States, Europe, Central and South America, Southeast Asia and other places are all in use. China's research in this area has also made great progress. The State Science and Technology Commission issued the “Study on Feeding Microbial Additives and Their Applications” during the “Eighth Five-Year Plan” period. In recent years, it has been widely used in the breeding industry in many provinces in China and has achieved very good results.

1. Microbial Feed Additives

The primary problem with microbial feed additives is the selection of appropriate strains. Since many bacteria have a host-specific relationship with the host to form a donor-recipient relationship, the microbial feed additive strain is preferably isolated from the animal's digestive tract to facilitate the colonization of bacteria in the additive by the host. Second, the breeding rate of the selected strains should be high so that they can quickly occupy the digestive tract, and the bacteria can have a strong ability to survive in an acidic environment. Again, the selected strain must have strong acid-producing ability to facilitate digestion and absorption of digestive tract nutrients. Only in this way can feed utilization be improved.

According to the regulations of the American Alltech Biotechnology Center, bacteria used as feed additives should have more than 70% resistance to cholic acid. U.S. Food and Drug Administration released in 1989 that can be used as feed additive and has no side effects on humans and animals: Aspergillus niger, Aspergillus oryzae, Bacillus coagulans, Bacillus lentus, Bacillus licheniformis, Bacillus pumilus, Bacillus subtilis ( Non-antibiotic-producing strains only), Bacteroides amyloliquefaciens, Bacteroides pilosicoli, Bacteroides ruthenica, Bacteroides succinogenes, Bifidobacterium adolescentis, Bifidobacterium animalis, Bifidobacterium bifidium, Bifidobacterium infantis, Long Bifidobacterium, Bifidobacterium thermophilus, Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus celloulis, Lactobacillus curvii, Lactobacillus delbrueckii, Lactobacillus plantarum, Lactobacillus plantarum, Leuconostoc mesenteroides, Lactic acid Pediococcus, Pediococcus Pediococcus, Pediococcus pentosaceus, Propionibacterium freudenii, Propionibacterium chevalier, Saccharomyces cerevisiae, Streptococcus cremoris, Streptococcus lactis dibutylketone, Streptococcus faecalis, Streptococcus lactis, Streptococcus thermophilus and so on.

2. Mechanism of Action of Microbial Feed Additives

The mechanism of action of microbial feed additives is not fully understood yet, but the results of the combined effects of applications in the aquaculture industry are as follows.

2.1 Balance the number of microorganisms in the digestive tract

Various kinds of microbial populations are found in the intestines of various domestic animals and poultry, and they are interdependent and mutually restrictive and constitute the balance of microorganisms in the digestive tract. In this micro-ecology system, dominant populations play a decisive role in the entire bacterial population. Once the dominant populations lose their effect, micro-ecological imbalances occur. The use of microbial additives can exogenously supplement beneficial bacteria, maintain the number of beneficial microorganisms, and maintain the normal flora. Feeding micro-ecological additives for feeding, beneficial microorganisms rapidly multiply after reaching the intestine, occupy an absolute advantage in quantity, consume a lot of oxygen in the breeding process, and cause adverse and harmful bacteria to survive and reproduce the environment (because harmful bacteria are mostly aerobic bacteria) , At the same time, it can also reduce the pH value by producing antibacterial substances (such as organic acids, etc.), and compete with harmful bacteria for nutrients or attachment sites to inhibit the growth of other pathogenic microorganisms, so as to maintain or restore the balance of microbial communities in the intestinal tract to achieve the effect of preventing disease and promoting growth. .

2.2 Adjusting and supplementing the nutritional composition of various livestock and poultry

Beneficial microorganisms can metabolize and produce various enzymes, amino acids, vitamins (such as vitamin K, C, B1, B2, etc.) during the survival and reproduction in the digestive tract of livestock and poultry. For example, yeasts and Bacillus can produce lipase, amylase, and protease. , directly decompose and digest feed nutrients. Some microorganisms can produce enzymes or phyto- plums that decompose complex sugars, improve the physical properties of digestive tract chyme, or eliminate anti-nutritional factors in diets, directly increase feed conversion rates, and promote animal growth and production.

2.3 Prevent harmful substances and protect the environment

Feed microbiological additives can promote the digestion and absorption of nutrients in the digestive tracts of domestic animals and poultry, thus reducing the production of ammonia and amines, and can reduce the content of ammonia in the intestinal contents, feces, and portal veins, and the cresol and intestinal creatinine. The content of wolfberry reduces fecal odor and purifies the environment of livestock and poultry houses. In addition, it can also grow in the intestine to form a dense membrane flora, forming a biological barrier to prevent the absorption of harmful substances.

2.4 Improve immunity and produce non-specific immune modulatory factors

Microbial feed additives can increase the level of antibodies in animals, or increase the activity of macrophages, enhance the body's immune function, and kill invading bodies to pathogens in time, thus preventing the occurrence of diseases.

2.5 Improve breeding ability of breeder and breeder

A series of activities of the beneficial microorganisms in the microbial feed additive in the animal body, and various enzymes and unknown factors generated in itself and in their metabolic process can stimulate the reproductive system of breeding stocks and breeding birds, improve their functions, and increase their hormone levels in the blood. The content increases the quantity and quality of sperms and eggs, thereby increasing the fertilization rate, the breeding rate of breeder eggs, the breeding stock, and the survival rate of breeding animals, thereby providing healthy animal offspring.

In summary, the application of microbial feed additives in the aquaculture industry can reduce the use of various drugs in the aquaculture industry (such as terramycin and antibiotics), reduce drug residues in livestock and poultry products, and increase feed intake. The utilization of various nutrients in the crop, thereby reducing the cost of raising the crop, and greatly increasing the economic efficiency of the breeding industry.