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3.b-GLUCAN
-Glucans are polysaccharides of D-glucose monomers linked by glycosidic bonds. -glucans are a diverse group of molecules which can vary with respect to molecular mass, solubility, viscosity, and three-dimensional configuration. They occur most commonly as cellulose in plants, the bran of cereal grains, such as oats and barley, and to a much lesser degree in rye and wheat, the cell wall of baker's yeast, certain fungi, mushrooms and bacteria. -glucans can be more diverse than molecules like starch. For instance, a -glucan molecule can be comprised of repeating D-glucose units linked with beta glycosidic bonds at one position like starch, but have branching glucose side chains attached to other positions on the main D-glucose chain. These smaller side chains can branch off the -glucan backbone" (in the case of starch, the backbone would be D-glucose chains linked at the (1,4) position) at other positions like that of the 3 and 6 position. The beta(1,3)D-glucans from yeast are often insoluble. Those extracted from grains tend to be both soluble and insoluble.
THE NEGATIVE EFFECT OF b-GLUCAN
High concentration of b-glucan can hold a great amount of water, form gelatin like structure and increase chime viscosity of intestine.
4.MANNAN
Mannan is a plant polysaccharide that is a polymer of the sugar mannose. Detection of mannan leads to lysis in the mannan-binding lectin pathway. It is generally found in yeast, bacteria and plants. It shows (1-4) linkage. It is a form of a storage polysaccharide. Mannan is widely distributed in nature, which is the main ingredient of non-starch polysaccharide (NSP).
1). Reduce the absorption of nutrients, affect the conversion rate and animal growth performance;
2). Interact with microbiota in gastrointestinal posterior, result in anaerobic fermentation and generate large amount of clostridium.Some clostridium can generate toxins and thus decrease animal growth.
THE PROBLEMS OF FEEDSTUFF IN APPLICATION
APPLICATION PROBLEMS OF CORN AND OTHER BY-PRODUCTS IN FEEDSTUFF
Non-starch polysaccharides (NSP), mainly including xylan and cellulose, are the anti-nutritional factors in corn and other by-products. The concentration of xylan is about 9.1% ~ 18.4%, cellulose is about 6.3%~14.7% in corn and its by-products. NSP is anti-nutritional which can affect animal’s absorption of nutrient.
THE NEGATIVE EFFECT OF WHEAT AND ITS BY-PRODUCTS
The major problem of wheat and its by-products, like wheat bran, wheat-middlings is that wheat contains high concentration of xylan. Xylan can increase the viscosity in animal intestinal and affect nutrient digestibility.
THE NEGATIVE EFFECT OF SOYBEAN MEAL
1)Contain high level of NSP.Soybean meal, a by-product of soya oil industry, contain high level of NSP, and the total amount can be more tha