As standard of living rising, the national concern about the safety of meat quality is growing. The negative effects brought by high dose of antibiotics by the domestic high attention. Limit the use of antibiotics, seeking new alternatives to become scholars focus on animal nutrition. Studies have shown that g of a prebiotic, fructooligosaccharide, which is added in the diet can increase animal production performance, improve the effect of immunity and reduce the case fatality rate (Mr Chirac, etc., 2011; Yan Guiling etc., 2008; YouJinMing etc., 2010). Yeast mannose oligosaccharides (MOS) as a new type of green Feed additives, because of its strong stability, high safety and good environmental protection and overcome the lack of antibiotics and acidulant, etc, are widely used in animal husbandry (far calderon, etc., 2013).
1 yeast MOS
Currently, the main Feed use of MOS is yeast cell wall extract. MOS is extracted from yeast cell wall or between the mannose mannose and glucan by alpha 1, 2, only alpha 1, 3 and a - 1, 6 glycosidic bond of oligonucleotides chitosan (Mitsuoka, etc., 1987; Fishbein, etc., 1998). Affected by the composition of its physical and chemical properties of MOS, usually soluble in water, insoluble in organic solvents, when added with a certain volume of organic solvent precipitation.
Sources of yeast cell walls of MOS stable under physiological conditions, MOS can bear the high temperature of Feed processing treatment (121 ℃, 20 min), and maintain the integrity of its structure and function is not damaged (jian-gang zhang, etc., 2012). Low relative molecular mass of MOS in animals with low viscosity, easy to transfer and transport in the body, at the same time the single stomach animals secretion of digestive enzymes can't break down the mannose. Flickinger etc. (2000) study found that MOS can directly enter the selectivity of the back-end is beneficial bacteria in the intestine of fermentation. Relative molecular mass of MOS cannot be used by the probiotics, has the stronger adsorption
The ability of the original fungus.
2 MOS biology function
2.1 interference with pathogen engraftment H lower gastrointestinal diseases
Nathan, etc. (1993) study table pounds, intestinal pathogenic bacteria (escherichia coli, salmonella and clostridium bacilli, etc.) of the cell wall or nap on that exogenous lectins, can this kind of lectin and sugar residues on the intestinal wall cells (D - mannose, beta - galactose and L fucose etc.) the combination of particularity. Many intestinal pathogenic bacteria such as salmonella species, e. coli, klebsiella and dysentery bacillus's blessing have mannose specific agglutinin (Ofek, etc., 1978; Oyofo, 1989). Research shows that methyl - alpha - D - pyran mannose glucoside with strong adsorbability, e. coli has interference of e. coli in the ability of colonization in intestinal tracts (Ofek, etc., 1978; Eshdat etc., 1981). Mirelman etc. The study found that e. coli adhesion to the intestinal epithelial cell wall, join the low poly mannose can quickly make the e. coli from intestinal epithelial cell falls off, and the common glucose and galactose is ineffective. Due to intestinal probiotics not combined with mannose specific exogenous lectins, as a result, MOS will not have adhesion and eliminate effects on bacteria. Intestinal probiotics and the intestinal pathogenic bacteria have the relationship of competitive exclusion, as a result of the limitation of MOS effective engraftment of intestinal pathogenic bacteria, as a result, MOS with functions of promoting the growth of intestinal probiotics and the intestinal microecological balance effective maintenance (Spring, 2000).
2.2 optimize the intestinal micro ecology environment
Single stomach animal gastrointestinal tract of enzyme digestion of sugar is mainly confined to only - 1, 4 glycosidic bond, for other forms of glycosidic bond decomposition ability is limited, yeast MOS of the glycosidic bond is alpha 1, 2, alpha 1, 3, and alpha 1, 6, so the single stomach animals cannot be separated yeast MOS. Studies have shown that MOS can promote the growth of a variety of lactic acid bacteria, lactic acid bacteria produce the large amount of volatile fatty acids (such as acetic acid, propionic acid and butyric acid) can reduce intestinal pH, inhibition of pH sensitive pathogenic bacteria proliferation (Flickinger, etc., 2000; Spring, etc., 2000). Wen-bin yue (2002) study, such as MOS can significantly reduce the concentration of e. coli in the cecum and colon quality in piglets, significantly improve the quality of cecum lactobacillus and bifidobacterium concentration (P < 0.05). Reduce the frequency of diarrhea piglets was 54%. MOS, home by interfering with pathogenic bacteria, promote the proliferation of intestinal probiotics 2 ways, effectively reduce the intestinal pathogenic bacteria content, reduce intestinal pH, provide nutrients to the intestinal epithelial cells, prompting probiotics play better immune, barrier and nutrition, and other functions.
2.3 stimulate mannose binding protein secretion, activation of the complement system appears
Ezekowitz etc that mannose binding protein (2003) study was a kind of acute phase proteins secreted by the liver, is an important effect in the body system and the effect of amplification system, is an important part of the machine body immunity dint. Janeway (1993) research thinks, MOS have the ability to stimulate secretion of hepatic mannose binding protein. Mannose binding protein can be a variety of specific binding of microbial surface with mannose residues and n-acetyl glucosamine for sugar base at the end of the glycoprotein, is not dependent on the antibody to start regulating role or complement activation level joint response, to protect themselves from organisms and harmful substances (Gu Yuanyuan, 2008). Mannose binding protein is currently found only can activate the complement system appears lectins, is the first line of defense in the body's natural immune factor, the activation of the complement system appears, pathogen recognition and the body to eliminate pathogen has huge role. If the body lacks enough mannose binding protein, will lead to the emergence of repeated infection.
2.4 enhance organism cellular immunity and humoral immunity
Study abroad, after the piglets fed MOS, can improve the quality of interleukin 2 in the blood concentration of T lymphocytes and the activity of small intestine original lymphocytes is enhanced, at the same time, the MOS can also promote the activation of lymphocytes release cytokines IFY - 1, to activate macrophages and promote its moved towards the infected area (Spring, 1998). There are more than at homeDate: 2015-08-21