|FOOTE, ANDREW - University Of Kentucky|
|HARMON, DAVID - University Of Kentucky|
|MCLEOD, KYLE - University Of Kentucky|
|BUSH, LOWELL - 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., Harmon, D.L., Brown, K.R., Strickland, J.R., Mcleod, K.R., Bush, L.P., Klotz, J.L. 2014. Constriction of bovine vasculature caused by endophyte-infected tall fescue seed extract is similar to pure ergovaline. Kentucky Beef Report. pgs. 13-15.
Interpretive Summary: The objective of the current experiment was to determine if the greater contractility produced by the extract is attributed to the presence of the other ergot alkaloids. This was accomplished by using the bovine lateral saphenous vein bioassay to represent peripheral vasculature and the right ruminal artery and vein bioassay to represent core vasculature, to compare endophyte-infected tall fescue seed extract with an endophyte-free tall fescue seed extract, ergovaline alone, and a mixture of commercially available ergot alkaloids mixed to mimic the endophyte-infected tall fescue seed extract alkaloid concentrations. Data from these experiments indicate that an extract of endophyte-infected tall fescue seed is capable of inducing a contractile response similar to a mixture of ergot alkaloids and ergovaline alone. Results support ergovaline as being primarily responsible for vasoconstriction, especially in the peripheral vasculature.
Technical Abstract: A mixture of ergot alkaloids does not increase the contractile response of peripheral bovine vasculature, but may increase the contractile response of foregut vasculature. Preliminary data indicated that an extract of tall fescue seed induced a greater contractile response in ruminal artery and vein than ergovaline. To determine if the increased contractility was due to the presence of other ergot alkaloids or an effect of the extraction procedure, the contractile response of bovine saphenous veins, right ruminal artery and right ruminal veins to a mixture of ergot alkaloids with similar concentrations to the endophyte-infected tall fescue seed extract, an endophyte-free tall fescue seed extract, and pure ergovaline were evaluated. Contractile response of the saphenous vein, ruminal artery, and ruminal vein were not different for the endophyte-infected tall fescue seed extract, the mixture of ergot alkaloids, and pure ergovaline. The endophyte-free tall fescue seed extract failed to induce a contractile response in any of the tissues. These results indicate that ergovaline is likely the main ergot alkaloid response for vasoconstriction, but other ergot alkaloids could be important in certain aspects.