Enzyme preparation is a functional feed additive. Its application in poultry farming can promote the digestion and absorption of nutrients, improve production performance and reduce environmental pollution. This article reviews the research progress of enzyme preparations in poultry breeding, puts forward the future development trend of enzyme preparations, and provides references for the application of enzyme preparations in poultry production.
The main components of animal feed include starch, protein, fat and some trace elements. A large amount of nutrients in feed cannot be digested and absorbed by animals, especially young animals have poor digestion and absorption capacity, mainly because livestock and poultry themselves cannot secrete enough digestive enzymes. The digestive enzymes in poultry farming can pre-digest the macromolecular nutrients starch, protein, cellulose and other substances that are not digested and absorbed by the intestinal tract, and turn them into small molecular nutrients that can be absorbed and utilized. Some functional enzymes can replace antibiotics to eliminate bacterial contamination in feed ingredients. Functional enzyme preparations have the advantages of improving gut microflora, participating in animal endocrine regulation, and improving hormone metabolism in poultry. Therefore, in poultry farming, the addition time, type and amount of enzyme preparations should be strictly controlled according to different basic diets of different poultry. The article mainly introduces the types of enzyme preparations and their application in poultry production, and provides a reference for the application of enzyme preparations in livestock and poultry breeding.
1 Types of enzyme preparations
Feed enzyme preparations can be divided into digestive enzyme preparations for the purpose of assisting digestion and functional enzyme preparations for the purpose of degrading single and multi-component anti-nutritional factors. Digestive enzymes can significantly improve the feed intake of animals, reduce the ratio of feed to weight, help animals digest macromolecular substances in feed, improve the utilization rate of animal feed, and reduce animal intestinal viscosity. Feed enzyme preparations can be divided into single enzyme preparations and compound enzyme preparations. Single enzyme preparations are generally pure enzyme preparations produced by microbial liquid fermentation; compound enzyme preparations are divided into two types: one is to formulate single enzyme preparations according to the growth needs of different livestock and poultry by compounding methods, and the other is to prepare single enzyme preparations. It is obtained by inoculating single strain or mixed strain on solid material medium by solid state fermentation method. A single enzyme preparation has limited effect in poultry, so the development of composite enzyme products has become a current research focus.
1.1 Digestive enzyme preparations
Amylase is widely found in animals (saliva, pancreas, etc.), plants (malt, arugula) and microorganisms. Corn is an important energy source in animal feed, and corn is rich in starch, which is good for animal digestion and absorption. However, Liu et al. found that the digestibility of cornstarch in chickens is not high, and the digestibility of cornstarch in the terminal ileum of chickens is lower than 82%. Young animals are immature and lack amylase in their digestive systems, resulting in wasted nutrients. The digestibility of cornstarch in the animal intestine is about 80%, and the remaining starch accumulated in the animal intestine can increase the intestinal viscosity, thereby affecting the animal digestion.
Feed is rich in protein, but only 80% of the protein is digested and absorbed by animals. Nitrogen, phosphorus and other elements in protein enter the environment with excrement and cause pollution. Adding suitable protease to the feed can improve the digestibility of protein, reduce waste of resources and reduce the cost of breeding. The use of proteases can improve animal growth performance. At this stage, acid protease is mainly added to the feed. The enzymatic hydrolysis site of protease has a certain specificity, so it is necessary to add a certain proportion of neutral protease and alkaline protease to achieve complete digestion and absorption of feed. Therefore, the combined use of multiple enzyme preparations should be considered in actual production.
Oil has the highest energy, and adding lipase to feed can improve the digestibility and utilization of nutrients in oil meal and meet the animal's demand for high-energy diet. Young animals lack the necessary lipase, but the growth of young animals requires a lot of energy. Therefore, adding exogenous lipase to the feed of young animals can reduce indigestion caused by high-fat diets and help young animals grow healthily. In the production, different feed lipases should be used according to the properties of the oil; multiple lipases should be selected according to the synergistic effect to improve the digestibility of the oil. For different animals at different growth stages, a suitable lipase formula should be sought to maximize the cost-effectiveness in combination with endogenous enzymes; all feed enzymes need to consider salinity and alkali resistance, bile salt tolerance and some metal ion properties, etc. The right part works.
