Types and application of green aquatic feed additives
Live bacteria preparation
Living bacteria preparation is a microbial preparation produced by industrial anaerobic fermentation of animal beneficial bacteria. The action mechanism of live bacteria preparation on aquatic animals can be summarized as follows: beneficial microorganisms in live bacteria preparation enter aquatic animals to form dominant flora, compete with harmful bacteria for oxygen attachment sites and nutrients, and competitively inhibit the growth of harmful bacteria, thus regulating the normalization of intestinal flora; Microbial metabolism produces organic acids, reduces intestinal PH value and kills acid-resistant harmful bacteria; Produce lysozyme, hydrogen peroxide and other substances, which can kill potential pathogens; Produce various digestive enzymes, which is beneficial to nutrient decomposition; Synthesis of B vitamins, amino acids, unknown growth promoting factors and other nutrients; Directly stimulate intestinal immune cells to increase local immune antibodies and enhance the body's disease resistance.
The application of live bacteria preparation in aquaculture has the following three characteristics: first, the diversity of functions can promote growth and improve the output of aquatic products such as fish, shrimp and crab. It is reported that the yield can be increased by10 ~ 30%; Improve the quality of aquatic products; It has many functions such as disease prevention and disease resistance. Can improve the survival rate of fingerlings by 5-20%; Second, it has wide adaptability. The existing live bacteria preparations for aquatic products have been tested and demonstrated in Sichuan, Liaoning, Guangdong and other places, and all of them have shown obvious effects. The main reason is that it is mainly influenced by the living bacteria environment of aquatic organisms, and the external environment has relatively little influence on its function. At present, there are few reports about special live bacteria preparations for shrimp and fish at home and abroad. Third, high security. Most aquatic bacteria preparations are separated and purified from the microbial system in healthy aquatic animals, and then act on aquatic animals, which will not cause any harm to aquatic animals and will not remain in water and fish.
Saccharicterpenin
Glycoterpenoids are natural bioactive substances composed of sugar (≥30%), sugar conjugates (≥30%) and organic acids. The active ingredients of saccharicterpenin have stable performance and are safe to use, and there is no contraindication when used together with other feed additives. The addition amount of saccharicterpenin in feed is 200-500g/ton, which can completely replace antibiotics, and has no residue and no pollution to the environment. After feeding, it can significantly enhance the immunity and disease resistance of aquatic animals, promote growth, improve daily gain and feed conversion rate, and has anti-stress and antioxidant effects. At the same time, it has a strong preventive effect on intestinal bacterial diseases. The experiment shows that the quality of aquatic products added with sugar terpenoids feed additives has been improved, which meets the requirements of green production of animal-derived foods and has remarkable social and economic benefits.
oligosaccharide
Oligosaccharides, also known as oligosaccharides, are the general name of oligomers with linear or branched chain structure, which are composed of 2- 10 glycosyl groups connected by glycosidic bonds. There are many kinds of oligosaccharides, but they are mainly used as feed additives at present, including isomaltose, isomaltotriose, isomaltose, pentose, fructooligosaccharide, fructooligosaccharide, galactooligosaccharide, mannose oligosaccharide, soybean oligosaccharide, gentian oligosaccharide and xylooligosaccharide. Oligosaccharides can selectively promote the proliferation of beneficial bacteria in the intestinal tract of aquatic animals. These beneficial bacteria use oligosaccharide fermentation to produce short-chain fatty acids, reduce intestinal PH, inhibit the consumption of nutrients by pathogenic bacteria, and reduce the production of toxic and pathogenic metabolites, thus maintaining and improving the health of aquatic animals.
Some oligosaccharides can improve the immune response of the body to drugs and antigens, and enhance the immune ability of aquatic animals. Compared with live bacteria preparation, oligosaccharide is more stable, has high tolerance to harsh environmental conditions such as granulation, puffing, oxidation, storage and transportation, can resist the inactivation of gastric acid, and overcomes the shortcoming that live bacteria preparation is difficult to colonize in intestinal tract. In addition, it is non-toxic and has no side effects. Therefore, although the current production efficiency is low and the production is difficult, its development and application prospect in aquatic feed is still very broad.
enzymic preparation
Enzyme preparation is an industrial product containing a single enzyme or a mixed enzyme processed by a specific production process. At present, except for phytase which has a single enzyme product, most other feed enzyme preparations are compound preparations containing multiple enzymes. Cellulase, β-glucanase, xylanase, amylase, protease, pectinase and phytase are widely used. Some of these enzymes can be secreted by aquatic animals themselves, such as amylase and some proteases; But some aquatic animals can't secrete it themselves, such as cellulase, β -glucanase and xylanase. Enzymes can destroy plant cell walls. By decomposing non-starch polysaccharides (NSP) such as cellulose, hemicellulose and pectin, these unusable polysaccharides can be decomposed into small molecules that can be digested and absorbed, exposing nutrients such as starch and protein protected by cell walls, making them more nutritious. Enzyme preparation can also reduce the viscosity of viscous chyme caused by soluble NSP. Enzyme preparation can also destroy the stable phytate phosphorus structure and improve the utilization rate of phosphorus and other nutrients in feed.
The application of feed enzyme preparation in aquaculture has four main functions: promoting feed digestion and absorption, and promoting the feeding and growth of aquatic animals; It has the function of improving digestive system and certain anti-inflammatory effect; Prevent and slow down the stress response of aquatic animals; Improve feed effect and reduce nutrients in feces.
Chinese herbal medicine feed additive
In recent years, Chinese herbal medicine has attracted people's attention because of its advantages of no drug resistance, no drug residue, little side effects, remarkable effect and rich resources. Chinese herbal medicine contains protein, amino acids, vitamins, oils, resins, sugars, plant pigments, macroelements and various trace elements, and also contains a large number of organic acids, alkaloids, polysaccharides, volatile oils, waxes, tannins and some unknown growth-promoting active substances.
According to research, Chinese herbal medicine also contains a variety of immunologically active substances. The role of Chinese herbal medicine additives in aquaculture is mainly manifested in the following four aspects: promoting the feed intake of aquatic animals (food attraction) and improving the feed intake; Reduce feed coefficient and increase weight gain rate; Prevent and control the occurrence of fish diseases and improve the survival rate; Replace some mineral salt additives and vitamin additives.
Yeast cell wall
Yeast cell wall is a brand-new natural green additive, and its product is egg yolk powder, which is a special by-product extracted from soluble substances in the production of beer yeast. It is mainly composed of β-glucan, mannan oligosaccharide, glycoprotein and chitin, accounting for about 85% of the dry weight of cell wall. Studies have shown that yeast cell wall can stimulate and enhance immunity; Maintain the balance of living bacteria, control diseases and other physiological functions. Aquatic animals not only face the pressure of water environment change, but also suffer from many common diseases. Traditional disease prevention measures are limited. Adding low-dose yeast cell wall to aquatic feed can enhance the resistance of fish, shrimp, turtle and crab to various major diseases and environmental changes and improve the survival rate.
Feeding healthy fish and shrimp with yeast cell wall can improve the survival rate of seedlings by 20%-40% and the survival rate in growth period 10%-20%. Therefore, using yeast cell wall to make special feed is considered to be an effective means to enhance the disease resistance and promote the growth of aquatic animals.
carnitine
Carnitine, also known as carnitine, was first discovered in muscle extract by Krimberg and Gulewitsch in 1905. L-carnitine has two variants (L-form and R-form), and only L-carnitine exists in nature. Carnitine is a water-soluble compound, which plays a great role in people and animals, and is a vital active substance necessary for organisms. In recent years, there have been some studies on the effect of carnitine on the growth performance of aquatic animals at home and abroad. Most research results show that carnitine has the following four effects on aquatic animals: increasing the weight gain rate of aquatic animals; Reduce the body fat of aquatic animals and improve meat quality; Save feed protein, reduce feed coefficient and improve the survival rate of aquatic animals; Improve the fish reproduction rate.
1On May 29th, 995, the State Council promulgated the Regulations on the Management of Feed and Feed Additives, which made the feed safety management in China step into the track of management according to law. Combined with the implementation of the Regulations, the Ministry of Agriculture has intensified the investigation and punishment of illegal drugs in feed and feed additives, and encouraged and developed green feed additive products to replace antibiotics and other feed additives. This is of great significance for solving drug residues, protecting the environment and human health, and accelerating the export of aquatic products to earn foreign exchange. However, under the current situation of aquaculture development in China, it is unrealistic for green aquaculture additives to completely replace antibiotics in aquaculture, and it takes a gradual process for antibiotics to withdraw from the historical stage of aquaculture. It is believed that with the steady development of aquaculture and feed industry, the continuous innovation of aquatic animal nutrition theory, the general improvement of people's living standards and the continuous enhancement of safety awareness, more green aquatic feed additives will come out to meet the needs of production and life.