W.H. Hoover

A method for partitioning neutral detergent-soluble carbohydrates†

A method was developed to fractionate the neutral detergent-soluble carbohydrates (NDSC) in feedstuffs. Differential solubilities of carbohydrates in 80:20 (v/v) ethanol/water were used to partition NDSC into organic acids (OA) and mono- and oligosaccharides soluble in ethanol/water from starch and neutral detergent-soluble fibre (NDSF) which are insoluble. Mono- and oligosaccharides (total ethanol/water-soluble carbohydrate) were measured on the ethanol/water extract, and starch was measured on the ethanol/water-insoluble residue. The OA and NDSF, the two most compositionally diverse NDSC fractions, were estimated by difference. The method allows partitioning of the NDSC on a nutritionally relevant basis into (1) organic acids, (2) total ethanol/water-soluble carbohydrate, (3) starch and (4) neutral detergent-soluble fibre. The methods involved in this fractionation are relatively simple or are commonly used. © 1999 Society of Chemical Industry

Rumen Digestive Physiology and Microbial Ecology

The rumen is a dynamic, continuous fermentation compartment that provides a suitable environment for a variety of species of anaerobic bacteria, protozoa, and fungi. These microorganisms have a complex series of interactions with the feeds supplied to the host, with some using particulate matter as both sources of nutrients and sites of sequestration to avoid being washed from the rumen by the rapid flow of fluids. Because of the ability to use soluble nutrients and to reproduce rapidly, other microbes associate primarily with the liquid phase of the rumen contents. Due to the metabolic activity of all microbial populations, feeds are converted to microbial matter and fermentation end products, which serve as nutrients for the ruminant. Optimum feed utilization by ruminants is dependent on achieving maximum rumen fermentation and flow of microbial protein to the duodenum. At this time, it is clear that the major nutrients required by the microbial populations include both fibrous and nonfibrous sources of carbohydrates and nitrogen in the form of ammonia, amino acids, and peptides. In spite of five decades of research, the exact quantities and sources of these nutrients that will result in optimum rumen fermentation rates and microbial yields are only partially known.