Submitted to: Energy Metabolism of Farm Animals Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: September 13, 1997
Publication Date: N/A
Technical Abstract: The objective of this experiment was to identify the components of ruminant gut tissue oxygen consumption and nutrient use which are sensitive to diets differing in energy density (ie. forage vs. grain) and different planes of nutrition (ie. fed at maintenance vs. fed above maintenance). Twenty-eight (25 kg BW) wether lambs were fed either 75% concentrate or 75% roughage pellets for 49 days at maintenance or twice maintenance. At slaughter, rumen epithelial and duodenal cells were isolated for analysis of metabolite oxidation in 90 min incubations in vitro. Substrates evaluated include acetate, butyrate, propionate, glucose, glutamate, and glutamine. Dose response curves were developed in order to determine a Vmax and a Kox per million cells for each substrate tested. Vmax and Kox have been developed for both oxidation of substrate to carbon dioxide and for the production of intermediary metabolites beta hydroxybutyrate, acetoacetate, and lactate by the isolated cells during 90 minute incubations. Neither the capacity to oxidize substrate nor the dose at which half maximal oxidation occurred were affected by dietary treatment in the ruminal epithelium. Currently, it appears that the metabolic characteristics of the rumen epithelium are not dramatically affected on a cellular basis and thus, increases in cell number are the most likely cause of the increased oxygen consumption associated with forage diets and increased metabolizable energy intake.