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United States Department of Agriculture

Agricultural Research Service

Title: Influence of Energy Density and Metabolizable Energy Intake on Substrate Metabolism by Ruminal Epithelial Cells Isolated from Sheep

Authors
item BALDWIN, RANSOM
item Mcleod, Kyle
item Dawson, Tadd

Submitted to: Energy Metabolism of Farm Animals Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: January 10, 1998
Publication Date: N/A

Interpretive Summary: An experiment was conducted to determine the effects of forage versus concentrate and metabolizable energy intake on nutrient use by isolated rumen cells. Twenty-eight crossbred lambs were fed diets containing either 75% forage or 75% concentrate at two different intakes. Cells isolated from the rumen were incubated in the presence of multiple concentrations of nutrients (acetate, propionate, butyrate, glucose, glutamine, and glutamate). Use of butyrate and propionate were greater in cells isolated from concentrate fed lambs as compared to those isolated from forage fed lambs, while use of acetate was enhanced with increasing energy intake. The pattern of nutrient use is consistent with the thought that volatile fatty acids are the primary nutrients used by rumen cells.

Technical Abstract: An experiment was conducted to determine the effects of dietary energy density and metabolizable energy (ME) intake on substrate oxidation by isolated rumen epithelial cells. Twenty-eight crossbred lambs (20.1ñ.3 kg BW) were fed diets containing either 75% forage or 75% concentrate at either 0.416 or 0.757 MJ MEù(kg BW.75)-1ùd-1 for an average of 52 d. Lambs were slaughtered and epithelial cells isolated from the rumen were incubated in the presence of multiple concentrations of oxidizable substrates (acetate, propionate, butyrate, glucose, glutamine, and glutamate). Oxidation rates of butyrate and propionate were greater in epithelial cells isolated from concentrate fed lambs as compared to those isolated from forage fed lambs, while rates of acetate oxidation were enhanced with increasing ME intake. However, these changes in VFA oxidation rates did not affect the overall predicted Michealis-Menton parameter estimates, Kox and Vmax. The estimated Kox values are consistent with the contention that VFA are the primary oxidizable fuels used by rumen epithelial cells. In conclusion, while subtle changes in VFA oxidation do occur, overall oxidative capacity of rumen epithelial cells is largely unaffected by diet or ME intake.

Last Modified: 7/28/2014
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