Abstract: the enzyme is a kind of produced by living cells which has the function of biocatalysis in polymer material, enzyme preparation is to organisms to produce enzymes purified products after processing, the role of mild conditions, low energy consumption and chemical pollution, and feeding enzyme preparation as a kind of green biological catalyst, can increases the feed resource utilization and economic benefits, controlling pollution of the environment. The classification, production methods and development status of forage enzyme preparations were reviewed, and the development of enzyme preparations was prospected.
Enzymes are a kind of macromolecular substances with biocatalysis function produced by living cells. Most enzymes are proteins and participate in various biochemical reactions of the organism. Enzyme has specificity and high efficiency. The so-called specificity refers to that an enzyme can only catalyze the reaction of one or a class of specific substrates, but the specificity of an enzyme is not absolute. Sometimes, it can also catalyze a variety of substrates with similar chemical structures. High efficiency means that the catalytic efficiency of enzymes is higher than that of inorganic catalysts. Enzyme widely exists in the organism, especially microorganisms such as bacteria and fungi, enzyme preparation was extracted from animals, plants and microorganisms processed with enzyme properties of a class of substances, main effect is catalytic food processing occurred during the production of various kinds of chemical reactions, such as main characteristic for high catalytic efficiency and high specificity, in addition, also a moderate role in the process of reaction conditions, low energy consumption and chemical pollution caused by the small, in the textile, food, flour processing and fruit processing industry, etc.), detergents, paper, leather, feed, environmental protection, medicine and energy development and wide application.
1· Classification of forage enzyme preparations
There are many kinds of forage enzyme preparation, which can be divided into digestive enzyme and non-digestive enzyme. Among them, the digestive enzymes such as protease, amylase and lipase, according to the optimal pH of different reaction time, protease and can be divided into acidic, neutral and alkaline protease, the enzyme is mainly used for degradation of materials such as starch and protein in the animal gut, making it a peptide and peptone small molecules, such as animal digestion and absorption. Digestive enzyme is refers to the animal itself cannot produce to the enzymes in the digestive tract, mostly derived from microorganisms, such as enzymes can digest the animal itself can't digest the material, or degradation of some anti nutritional factors, mainly including cellulase, hemicellulase, phytase, beta glucan enzyme, pectinase, xylanase and mannase etc. The main function of non-digestible enzymes is to crack cell walls, which typically consist of fibrotic polysaccharides (mainly cellulose), matrix polysaccharides (pectin, hemicellulose and a small amount of glycoprotein), and shell-forming substances (mainly lignin). The digestive enzymes that destroy the fiber cell walls, on the one hand, make the package of starch, protein and minerals to release, use and digest, on the other hand, the cellulose of degraded into digestible absorption of reducing sugar, so as to improve livestock and poultry feed dry matter, protein, crude fiber, starch digestibility and minerals, etc. Non-digestive enzymes in the mucinous polysaccharides hydrolase, such as -glucanase and xylanase is the corresponding material in the feed hydrolysis, eliminate his digestion and absorption of nutrients adverse reactions, and thereby improve the utilization rate of feed.
It can be divided into single enzyme preparation and compound enzyme preparation according to its composition type. Single enzyme preparations such as amylase, protease, lipase, -mannanase, cellulase and phytase. Compound enzyme preparation is composed of one or several single enzymes as the main body, plus other single enzymes mixed, or obtained by fermentation of one or several microorganisms. Under normal circumstances, the use effect of compound enzyme preparation is better than that of single enzyme preparation, but it is not to say that the more kinds of enzyme in compound enzyme preparation is the better, but to combine the physiological characteristics of animals and feed raw materials to determine the kind of enzyme.
In compound enzyme preparation each kind of enzyme complement each other, complement each other, destroy the anti-nutrient factor in feed raw material, promote animal growth thereby, improve animal immunity, and animal production performance also has certain enhancement.
2· Production method of forage enzyme preparation
At present, the enzyme preparation produced in the feed industry is basically microbial fermentation, the production methods include solid fermentation and liquid fermentation. Solid state fermentation, also known as surface fermentation, the enzyme activity obtained is high, the enzyme system is complete, the production cost is low, its shortage lies in the production scale is small, the output is not easy to expand, the production workers labor intensity is big; Liquid fermentation has the advantages of large production scale, small labor intensity of production workers, high degree of mechanization, easy automatic control, easy access to high-vitality high-quality goods, etc. However, due to high technology and labor costs, equipment investment, limited its application, currently, China's production of forage enzyme preparation mainly adopts the solid-state fermentation method.
With the development of human society, science and technology are also making more and more progress, and the research and production technology of enzyme preparations are also making continuous progress. Various technologies are also being applied in the research and production of enzyme preparations. Among them, genetic engineering technology has been applied in the research of enzyme preparations in most countries in the world, especially in developed countries. The benefits of gene engineering technology is that it not only can improve the yield of enzyme also can increase the stability of enzyme, in addition, the slow growth of plants and animals to produce the enzyme genes, or produced by originally without approval of harmful microorganism enzyme genes, cloning can also through the genetic engineering technology to the safe, rapid growth and high yield of microbe, shifted to microbial production. Such as aspergillus Niger phytase available and pichia microorganisms such as production, through the restructuring of the genetic engineering technology, restructuring and summarized fermented to make the efficient expression of phytase, through determination, found that the content of phytic acid in the fermented liquid enzyme to 6 ~ 8 U/mL, than the original strains producing enzyme content increased 3 000 times, significantly improve the rate of enzyme production.
3· Development status of enzyme preparations in China
According to the development status of enzyme preparation industry in China, it is divided into three stages: starting, rising and rapid development. In terms of the annual production of enzyme preparations, it was 480,000 t in 2005 and 775,000 t in 2010, increasing by 295,000 t or 10.1%. With the development demand of the society, the application field of enzyme preparation in China has been constantly extended, and its technology has been constantly innovated, so that in recent years, the enzyme preparation industry in China has been showing a growing trend, the growth rate has been maintained at about 10%.
Feed enzyme preparation is a new feed additive with the continuous development of enzyme preparation industry and feed industry, its appearance is nearly 50 years. In 1991, Perney adding phytase in corn, soybean meal diet, detect the pig of phosphorus in feed utilization ratio increased by 30%, John Coihl add 600 in pig diet FTU/kg, compared with the control group, increase quality improves the growing swine 21. 62% ~ 62. 31%, is expected to fall heavier than ten, more than 11%, at the same time of calcium, magnesium, phosphorus, zinc and copper absorption rate and deposition rate are also improved. In China, the research on forage enzyme preparation began in the 1970s. At the very beginning, the production of koji was carried out and applied to fermentation feed. Due to the restriction of technical route, use method and hybrid strain, it finally evolved into natural strain fermentation, resulting in the loss of organic nutrients. Then for a period of time, the enzyme preparation of the research stalled for a time. Until the late 1980s, with the development of animal husbandry, foreign forage enzyme preparations began to enter the Chinese market, which stimulated the development of enzyme preparations in China, and enzyme preparations were successively produced in China. In the 1990s, China's feed enzyme preparations began to develop rapidly, as a new feed additive, it can improve the digestion and absorption rate of feed nutrients, improve the quality stability of mixed feed, but also reduce the pollution of the breeding industry to the environment. Because of its high efficiency, non-toxic and no adverse reactions, feed enzyme preparation has become the fastest growing part of the enzyme industry in China, and its application effect has been recognized. In recent years, the market scale of enzyme preparation in China is gradually expanding.
Such as corn and soybean meal feed raw material prices continue to rise, compound feed in China is not only limited to the general type of corn, soybean meal diet, and on this basis to join different proportions of barley, wheat or cotton pulp non-conventional feed raw materials, such as the addition of these unconventional feed ingredients makes feeding the application of enzyme preparation is becoming more common, its position in the feed industry is also rising, this kind of feed ingredients there are a large number of antinutritional factors, compared with the corn and soybean meal, the price is low, so as they flood, will further stimulate the non-starch polysaccharide enzymes such as its application in feed.
4· Development trend of forage enzyme preparation
As a kind of green biocatalyzer, forage enzyme preparation can improve the utilization rate of feed resources and economic benefits, control environmental pollution, and develop forage enzyme preparation vigorously, which is the key to maintain this balance. Although the application prospect of forage enzyme preparation is broad, there are still the following bottlenecks: how to choose the appropriate way to add, whether to play a role directly in animals or to add in vitro; How to add according to different growth stages of animals; The diversity of feed materials and the difference between individual animals, how to add enzyme preparations; How to give full play to the advantages of solid fermentation and liquid fermentation to produce enzyme preparations with stable quality, high yield and low cost; How to resolve the relationship of mutual inhibition among compound enzyme preparations; How to solve the impact on animal microecological balance. With the development of human research methods and science and technology, feed additives will adapt to the requirements of different fields more and more, solve many problems in the development of human society, such as energy, food and environment, and achieve sustainable development.
