Carbohydrates canprovide up to 80% of the dry matter in animal diets, yet their specific evaluationfor research and diet formulation is only now becoming a focus in the animalsciences. Partitioning of dietary carbohydrates for nutritional purposes shouldreflect differences in digestion and fermentation characteristics and effectson animal performance. Key challenges to designating nutritionally importantcarbohydrate fractions include classifying the carbohydrates in terms of nutritionalcharacteristics, and selecting analytical methods that describe the desiredfraction. The relative lack of information on digestion characteristics of variouscarbohydrates and their interactions with other fractions in diets means thatfractions will not soon be perfectly established. Developing a system of carbohydrateanalysis that could be used across animal species could enhance the utilityof analyses and amount of data we can obtain on dietary effects of carbohydrates.Based on quantities present in diets and apparent effects on animal performance,some nutritionally important classes of carbohydrates that may be valuable tomeasure include sugars, starch, fructans, insoluble fiber, and soluble fiber.Essential to selection of methods for these fractions is agreement on preciselywhat carbohydrates should be included in each. Each of these fractions has analysesthat could potentially be used to measure them, but most of the available methodshave weaknesses that must be evaluated to see if they are fatal and the assayis unusable, or if the assay still may be made workable. Factors we must consideras we seek to analyze carbohydrates to describe diets: Does the assay accuratelymeasure the desired fraction? Is the assay for research, regulatory, or fielduse (affects considerations of acceptable costs and throughput)? What are acceptableaccuracy and variability of measures? Is the assay robust (enhances accuracyof values)? For some carbohydrates, we may have to accept that there arecurrently no acceptable, widely applicable analyses that meet these criteria,and seek to fill this analytical gap. Overall, there are good possibilitiesfor accomplishing the nutritional partitioning of carbohydrates. But to ensurethat this is done well, as a discipline, we need to continue our discussionson the basis for partitioning, on what fractions are actually significant, andrigorously evaluate proposed analyses to verify that they are analytically sound.
