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 plane 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. Rumen epithelium, reticulum, small intestine, liver and offal increased as a percentage of empty body weight in response to increased metabolizable energy intake. Forage fed animals had increased reticulum, omasum, abomasum, small intestine and large intestine mass as a percentage of empty body weight. The total, muscle and epithelial mass of 15 cm sections of duodenal, jejunal and ileal tissues increased in response to increased energy intake. Small intestinal length increased in response to increased ME intake. Tissue protein / mg dry matter was decreased in rumen tissue samples from lambs fed at twice maintenance. Total duodenal, ileal and ruminal RNA concentrations increased when energy intake increased but epithelial concentrations were not affected by either ME intake or diet composition. The activity of NA-K ATPase (nmoles PO4/ min/ mg protein) was decreased in the rumen, and ileum of lambs fed the high concentrate diet but was unaffected by intake. Thus, the observed increases in energy expenditure by the visceral tissues associated with increasing energy intake may be accounted for by tissue growth.