Currently, the production and application of feed enzymes are developing rapidly, making them one of the most important and promising feed additives in animal nutrition. The most commonly used enzymes in the feed industry are xylanase and phytase. Other enzymes such as alpha amylase enzyme, α-galactosidase, oligosaccharides, cellulase, pectinase, lipase, and protease are used less frequently.
There are many nutrients in feed that animals cannot utilize. For example, wheat, rye, and black wheat contain high levels of arabinoxylans. Oats and barley contain high levels of β-glucans and arabinoxylans, and plant protein feeds contain high levels of α-galactosidase and pectin. Legumes such as soybeans contain polysaccharides that are not digested in the small intestine. In adult animals, these substances are fermented by microorganisms in the large intestine, but 50% of the energy produced cannot be utilized. In addition, fermenting these substances in growing pigs results in the shedding of skin flakes.
The need for the rational utilization and development of feed resources. The complexity of feed structure and composition, as well as the lack or deficiency of endogenous digestive enzymes in animals, lead to low utilization rates of conventional feed (such as up to 10%-50% loss of feed energy through the digestive tract) and the inability to utilize unconventional feeds. Only by using enzyme preparations can this problem be effectively solved.
Animals lacking certain enzymes (such as cellulase in monogastric animals, phytase) due to physiological factors (such as young age, old age, high production) or pathological factors (such as stress, disease) only by using exogenous enzymes can the digestibility and utilization of feed by animals be improved, to promote the health and production performance of animals.
The need for ecological animal husbandry. The application of enzyme preparations can significantly improve the nutrient utilization of animals in feed, greatly reduce the excretion of organic matter, nitrogen, phosphorus, and other substances, and reduce environmental pollution.
Enzyme preparations are the safest feed additives. Compared to antibiotics, animal feed enzymes have no toxic side effects on animals, do not affect the quality of animal products, and are known as "natural" or "green" feed additives.
The activity of animal feed enzymes can be evaluated through in vivo assessment and in vitro measurement methods. Apart from in vivo methods, it is difficult to compare the quality of different enzyme preparations using other measurement methods. This is because different feed enzymes are produced by different microorganisms through fermentation, resulting in significant differences in the enzyme activity in the enzyme products. Moreover, the optimal pH value, temperature, and substrate affinity of enzymes secreted by various microorganisms are different. Currently, the main methods for determining the enzyme activity in feed are:
Reducing sugar method. This method uses substrates of enzymes synthesized chemically or extracted from nature. Enzymes react with substrates under specific conditions (temperature, pH, and substrate concentration). The reaction product is reducing sugar, the quantity of which is determined by colorimetry, while a standard curve is created. 1.0mg of reducing sugar produced per hour per milliliter or gram of enzyme under reaction conditions is defined as one unit of enzyme activity.
Other enzyme activity measurement methods include colorimetric, viscosity, immunological, and gel diffusion methods.
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