Feed non-starch polysaccharides for monogastric animals: classification and function

This review outlines the importance of understanding the true fibre content, which is the sum of non-starch polysaccharides and lignin, of feed in order for animal nutritionists to improve the precision of feed formulation in the future. The continuing use of crude fibre in feed formulation means that up to a quarter of the feed components, mainly non-starch polysaccharides and oligosaccharides that are lost during acid and alkali extractions, are ignored for ingredients such as soybean meal. Furthermore, the values for acid detergent fibre and neutral detergent fibre are not used for feed formulation. They also do not represent unique classes of chemically defined molecules. In some cases, neutral detergent fibre and acid detergent fibre values do not cover a large proportion of soluble fibre, for example, in leguminous crops that contain a high level of pectic polysaccharides. Non-starch polysaccharides and their associated lignin content represent the true fibre levels in ingredients and this is the basis from which structural and physicochemical elucidation of fibre can be attained. Only with such understanding will nutritional strategies be applied to target specific fractions/types of fibre in ingredients to produce desired nutritional and health outcomes in pigs and poultry. In this context, an example is given to illustrate how gut microbiota of animals can be manipulated to enhance production performance and immunity.