Nutritional function of small peptides and its application in animal husbandry production
Recent studies have changed the understanding of protein nutrition theory for a long time. Protein nutrition is not a simple amino acid nutrition, and small peptide nutrition also occupies a very important position. A peptide is a digested product of a protein. The number of amino acid residues is less than 50, called a polypeptide, an oligopeptide consisting of 2 to 10 amino acids, and a small peptide having 2 or 3 amino acid residues in an oligopeptide. Small peptides can be completely absorbed into the animal's circulatory system and directly metabolized by tissues, playing an important role in animal nutrition and metabolism. Small peptides have special nutritional and physiological functions. When they are supplied to animal protein nutrition in the form of small peptides, they can improve animal utilization of protein, enhance animal immunity, prevent disease and disease, improve animal product quality, and thus better Give play to the production potential of animals. 1 The nutritional function of small peptides 1.1 Accelerate protein synthesis A large number of experimental results show that the presence of amino acids in the diet directly affects the animal's protein metabolism, and small peptides in the blood circulation can directly participate in the synthesis of body proteins. In addition, other important organs of the body such as liver, kidney, skin, etc. can also fully utilize small peptides, such as the kidney is the main organ for digestion, absorption of small peptides and recapture of amino acids. Studies have shown that when animals use small peptides as a source of nitrogen, the deposition of protein in the body is significantly higher than the corresponding amino acid diet or complete amino acid diet. The main reason is that small peptide absorption does not produce competition similar to free amino acids in absorption, and therefore has a higher absorption rate, and thus the synthesis efficiency of the protein is also increased. According to the application of Hui et al. (1996), when the animal diet is completely supplied as a small peptide, the absorption of lysine and arginine will no longer appear antagonistic. Chen Yuguang et al (2006) believe that small peptides can promote the absorption of blood sugar and some amino acids in goats, thereby improving protein synthesis. 1.2 Promote the absorption of minerals Small peptides can form a chelate with mineral ions such as calcium, zinc, copper and iron to increase their solubility and facilitate the absorption of the body. Zhang Binli (2000) reported that casein phosphopeptide (CPP) binds to calcium in the small intestine of animals, thereby preventing the formation of calcium phosphate precipitation, increasing the dissolution of calcium in the intestine, and increasing the absorption and utilization of calcium. In the application of Hui et al. (1996), small peptide products were added to the laying hen diet. As a result, the iron and zinc contents in the plasma of the laying hens were significantly higher than those in the control group, and the eggshell strength was also significantly increased. 1.3 Improve animal immunity The small peptide has immunological activity, which can proliferate the beneficial bacteria in the digestive tract of the animal and improve the body's disease resistance. Jiang Peihong et al. (2007) showed that feeding a small peptide diet to a rex rabbit can promote the development of immune function and improve the function of immune organs. According to Zhou and Wang (2008), adding plant protein small peptides to the diet of suckling piglets in 4% can improve the number of lactobacilli in the cecal of the piglets and the level of immunoglobulin G in the serum, while at the same time making the large intestine The number of bacilli and Salmonella is reduced (Wang et al., 2003). 1.4 Physiological regulation Peptides are important active substances in the nervous system. Studies have shown that protein digestion produces many small peptides that act like neurotransmitters. At present, a variety of organisms with immunoregulatory activity, antihypertensive activity, opioid peptide activity, anticoagulant and diastolic vasoactive activity and antibacterial activity have been detected, isolated and purified from the hydrolysates of different animal milk proteins. Peptide. Peptide fragments similar to the amino acid sequence of the opioid peptide were also isolated from the enzymatic hydrolysate of casein and plant wheat gluten. 1.5 Proliferation Ruminal Microorganisms Small peptides can increase the growth rate and increase the number of rumen microorganisms in ruminants. The promotion of peptide growth on microorganisms depends mainly on the rate of fermentation of carbohydrates. For example, cellulosic materials, the fermentation rate is slow, the peptide does not play a role in microbial growth; but if the carbohydrate is a soluble sugar with a fast fermentation rate, the peptide can accelerate the growth of rumen microorganisms. Cheng Maoji et al (2004) showed that the higher the peptide concentration in the rumen culture solution, the faster the rumen bacteria grow faster, and the rumen bacteria have certain requirements for the peptide. Jones DF investigated the effect of peptide concentration on microbes in a continuous fermentation system. The crude protein content in the basal diet was 17.8%. Nitrogen was supplied by substituting urea with peptides. When 10% of total nitrogen was used, microbial production was maximized. CHANGZHOU CLD AUTO ELECTRICAL CO.,LTD , https://www.cld-leds.com