Enzymes are active substances produced by organisms and act as catalysts for various biochemical reactions within the body. The digestion, absorption, and utilization of various nutrients rely on the action of enzymes. Enzymes possess specificity, efficiency, and specificity. Thousands of enzymes have been discovered, with over 300 able to be artificially produced, and more than 20 are used in the feed industry. Enzyme products produced through biotechnology methods with activity are known as enzyme preparations. Enzyme preparations are a type of feed additive widely used in recent years. Most enzyme preparations used as feed additives are digestive enzymes. Due to their ability to effectively improve feed utilization, save feed raw materials, and without side effects such as drug residues or resistance, they are considered environmentally friendly feed additives.

Main Types of Enzyme Preparations as Feed Additives:

• Amylase: Includes α-amylase and glucoamylase. α-amylase breaks down starch molecules into easily absorbable medium and low molecular substances. Glucoamylase further hydrolyzes the medium and low molecular substances broken down by α-amylase into glucose for animal absorption and utilization.

• Protease: Proteases are hydrolytic enzymes that degrade protein peptide chains, including pepsin, trypsin, and papain.

• Cellulase: Cellulases break down the crystalline structure of cellulose, hydrolyzing cellulose molecules into oligosaccharide fragments and breaking down oligosaccharides into glucose.

• β-Glucanase: β-Glucan is widely found in various plant materials and has high viscosity, affecting nutrient transfer and absorption. β-Glucanase hydrolyzes large molecules like β-glucans, reducing substance viscosity in the digestive tract and promoting nutrient absorption. It is an important and widely used enzyme in enzyme preparations.

• Pectinase: Pectin is an anti-nutritional factor in plant materials that affects feed utilization. Pectinase effectively breaks down pectin, promoting the digestion and absorption of nutrients. It is also a commonly used feed enzyme preparation.

• Phytase: Most of the phosphorus in grains exists as phytic acid phosphorus. Animals do not secrete phytase, leading to low utilization of this phosphorus. By adding microbe-secreted phytase to feed, this phosphorus can be released, reducing the addition of inorganic phosphorus in feed, reducing feed costs, and decreasing phosphorus excretion in animal feces, reducing environmental pollution. It is currently one of the most widely used and promising green feed additives.

• Composite Enzyme: Composite enzymes are products formed by mixing two or more biologically active enzymes. They are formulated based on the characteristics of different animals and growth stages and have good effects. They are currently the most commonly used feed additives.

Functions of Enzyme Preparations as Feed Additives:

• Directly break down nutrients to improve feed utilization: Active enzymes can effectively break down some polymeric molecules in feed into nutrients that animals can easily absorb or further break down nutrients into smaller fragments for further digestion by other digestive enzymes.

• Eliminate anti-nutritional factors and improve digestive function: Enzyme preparations, especially β-glucanase, pectinase, phytase, and cellulase, can break down non-starch polysaccharides, pectin, phytic acid, and cellulose polymers in plant materials, reducing the viscosity of substances in the digestive tract, effectively eliminating the adverse effects of these anti-nutritional factors, and improving animal digestive performance.

• Activate endogenous enzyme secretion and increase enzyme concentration: Using enzyme preparations can provide more substrates available for various enzymes, activating the secretion of various digestive enzymes in animals, increasing the effective content of digestive enzymes, accelerating the digestion and absorption of nutrients, improving feed utilization, accelerating animal metabolism, and promoting animal growth.

Reasonable Application of Enzyme Preparations as Feed Additives:

• Scientific selection of enzyme preparation products: Most enzyme preparation products currently available on the market are composite enzyme preparations. The quality and efficacy of enzyme preparations mainly depend on the types, contents, activities, and stability of the enzymes. Since these indicators are currently difficult to detect and judge in application, special attention should be paid when selecting. Some large and professional enzyme preparation manufacturers can perform special treatments such as coating on enzyme preparation products to enhance enzyme activity and stability. Therefore, when selecting enzyme preparation products, it is best to choose products with good reputation and widely recognized by people, and conduct some trials before extensive application if conditions permit.

• Application based on animal species and growth stages: Due to the high specificity and specificity of enzymes, the types and quantities of enzymes in animal bodies are different for different animal species and growth stages. Therefore, to effectively exert and improve the effect of enzyme preparations, appropriate enzyme preparations should be selected based on the characteristics of different animals and growth stages. During the young stage of animals, the digestive system is not fully developed, and various digestive enzymes are insufficiently secreted, making it an ideal stage for using enzyme preparations. Generally, enzyme preparations containing multiple digestive enzymes, especially proteases and amylases, should be selected. In the adult stage of animals, digestive functions are more perfect, and various nutrients can be well digested. Therefore, when applying, enzyme preparations with anti-nutritional factors eliminating effects, such as β-glucanase, phytase, and pectinase, should be selected. For aquatic animal feed, enzyme preparations rich in protease and cellulase should be used. Generally speaking, the effect of using enzyme preparations in livestock is better than that in poultry, and the effect is better in the young stage than in the adult stage.

• Combine with feed raw materials: For feed formulations mainly composed of corn-soybean meal, enzyme preparations mainly containing xylanase, pectinase, and β-glucanase should be used; for those with more wheat, barley, and rice bran, enzyme preparations mainly containing xylanase and β-glucanase should be used; for those with more rice meal, rice bran, and wheat bran, enzyme preparations mainly containing β-glucanase and cellulase should be used; and for those with more rapeseed meal, sunflower meal, and high protein content, enzyme preparations mainly containing cellulase, protease, and xyloglucanase should be used.

• Interaction with other additives: Some experiments and studies have shown that when using enzyme preparations, appropriately adding some salts such as cobalt oxide, manganese sulfate, and copper sulfate can improve the efficacy of enzyme preparations. Enzyme preparations do not interact or antagonize with antibiotics, and enzyme preparations can be used synergistically with antibiotic growth-promoting additives.

• Pay attention to the influence of production processes: The main component of enzyme preparations is active enzymes. Enzymes are proteins and are sensitive to heat, light, and acid. During the feed production process, due to crushing, premixing, pelleting, and the influence of other additives, the activity of enzymes may be lost or even denatured. Therefore, when using enzyme preparations, the influence of production processes on enzyme activity should be minimized as much as possible. In particular, the temperature of pelleting should not exceed 75°C to ensure the effective efficacy of enzyme preparations.