Soybean Meal Carbohydrates Wasted and the Microbial Role for Improved Digestibility

This chapter discusses the role of nonstarch polysaccharide (NSP) and other indigestible carbohydrates on nutrient utilization, particularly those found in soybean meal. The NSPs are mainly concentrated in the cell walls of the endosperm, but are also found in the bran. They can be divided into two categories, the water-soluble beta-glucans and pectins and water-insoluble cellulose fractions. Indigestible components in poultry feeds include the fractions that are either totally undigested or incompletely digested. These include substrates for which poultry do not produce suitable enzymes, or that are inaccessible to enzymes because they are encapsulated or bound to other compounds. Increased levels of NSP in poultry diets, particularly the soluble fraction, lead to decreased nutrient digestion and absorption. Soybeans contain a number of ANFs that can result in a reduction in nutrient utilization, including oligosaccharides, NSPs, phytate, lectins, and trypsin inhibitors.