|FOOTE, ANDREW - University Of Kentucky|
|KRISTENSEN, NIELS - Southern Cattle|
|KIM, DOHYUNG - University Of Kentucky|
|KOONTZ, ANNE - University Of Kentucky|
|MCLEOD, KYLE - University Of Kentucky|
|BUSH, LOWELL - University Of Kentucky|
|HARMON, DAVID - University Of Kentucky|
Submitted to: Kentucky Beef Report
Publication Type: Experiment Station
Publication Acceptance Date: 9/1/2012
Publication Date: 1/1/2014
Citation: Foote, A.P., Kristensen, N.B., Klotz, J.L., Kim, D., Koontz, A.F., Mcleod, K.R., Bush, L.P., Harmon, D.L. 2014. Ergot alkaloids reduce rumen epithelial blood flow and volatile fatty acid absorption. Kentucky Beef Report. pgs. 16-19.
Interpretive Summary: Ergot alkaloids could potentially decrease blood flow to the rumen epithelium and consequently decrease nutrient absorption from the rumen. A decrease in nutrient absorption from the rumen could contribute to the observed unthriftiness of cattle consuming endophyte-infected tall fescue. An experiment was conducted to determine if ergot alkaloids alter rumen epithelial blood flow and volatile fatty acid absorption (VFA) from a washed reticulorumen of steers receiving endophyte-infected of endophyte-free tall fescue seed. Results from this experiment clearly demonstrate that ergot alkaloids present in endophyte-infected tall fescue reduce blood flow to the absorptive surface of the rumen. The reduction is blood flow is accompanied by a decrease in VFA absorption from the washed rumen. This reduction in VFA absorption could be partially responsible for the reduced growth rate and unthriftiness of cattle consuming common endophyte-infected tall fescue.
Technical Abstract: Ergot alkaloids have been shown to induce vasoconstriction of both peripheral and ruminal vessels. Constriction of ruminal vessels could lead to a reduction in epithelial blood flow thereby reducing nutrient absorption. The objectives of this experiment were to determine if steers receiving endophyte-infected or endophyte-free tall fescue seed have decreased rumen epithelial blood flow and volatile fatty acid absorption rates in the presence of differing levels of ergot alkaloids. Ruminally cannulated steers received endophyte-infected or endophyte-free seed for 7 days. On day 8 a washed rumen experiment was conducted. Three buffer treatments including a control, a low concentration of ergot alkaloids, and a high concentration of ergot alkaloids were incubated and epithelial blood flow and volatile fatty acid absorption were evaluated. Results show that ergot alkaloids induce a large reduction in epithelial blood flow as well as a reduction in volatile fatty acid absorption. The observed alterations in nutrient absorption could contribute to the decreased growth rates of cattle consuming endophyte-infected tall fescue.