The characteristic feature of ruminants is the fermentative nature of their digestion. This feature of their digestive system allows them to survive on high-fibre diets (Leng, 1970). The principal products of fermentation of dietary fibre are short-chain fatty acids | 11 Glucose and Short-chain Fatty Acid Metabolism . Brockman St. Peter s College Muenster Saskatchewan Canada Introduction The characteristic feature of ruminants is the fermentative nature of their digestion. This feature of their digestive system allows them to survive on high-fibre diets Leng 1970 . The principal products of fermentation of dietary fibre are short-chain fatty acids the most important of which are acetate propionate and butyrate Kristensen et al. 1998 Majdoub et al. 2003 . They account for more than 70 of the animals caloric intake Bergman 1990 . Since the dietary carbohydrate is fermented ruminant animals normally absorb little or no dietary carbohydrate as hexose sugar see Chapter 10 and their glucose needs must be met by gluconeogenesis even in the fed state Bergman et al. 1970 Lomax and Baird 1983 . In animals consuming high concentrate diets not all of the carbohydrate may be fermented but even then the absorption of hexose sugar from the gut accounts for less than one-third of the whole-body glucose turnover van der Walt et al. 1983 . Unlike in simple-stomached animals in ruminants the liver is incapable of having a net uptake of glucose Brockman 1983 . Metabolism of Glucose Methodology Any discussion of the quantitative aspects of metabolism requires a discussion of the techniques used to obtain the information. Estimates of the rates of production and utilization of metabolites in vivo have been made principally using two techniques isotope dilution and arteriovenous catheterization. Several isotopes may be used simultaneously. In addition isotope dilution has been combined with the arteriovenous difference technique. CAB International 2005. Quantitative Aspects of Ruminant Digestion and Metabolism 2nd edition eds J. Dijkstra . Forbes and J. France 291 292 . Brockman The use of isotope dilution techniques allows the measurement of the rate of turnover or irreversible loss of metabolites with minimal invasion of the body Leng 1970
