|Looper, M. - USDA-ARS-SPA-DBSFRC|
|Schrick, F. - UNIVERSITY OF TENNESSEE|
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: April 14, 2008
Publication Date: July 7, 2008
Citation: Aiken, G.E., Strickland, J.R., Looper, M.L., Schrick, F.N. 2008. Hemodynamics in the Caudal Artery of Beef Heifers Fed Different Ergot Alkaloid Concentrations. J. Anim. Sci. Vol. 86, E-Suppl. p 404. Technical Abstract: Doppler ultrasonography was used to compare hemodynamics in the caudal artery of heifers fed diets with either endophyte (Neotyphodium coenophialum) infected (E+; 1.14 µg ergovaline/g DM), endophyte free (E-; 0 µg ergovaline/g DM), or a mixture of E+ and E- (E+E-; 0.38 µg ergovaline/g DM) tall fescue seed in a base ration of chopped alfalfa hay plus concentrate. Eighteen endophye-naïve, Angus x Brangus heifers were stratified by BW into individual pens and fed the E- diet for a 7-d adjustment period. A 9-d experimental period followed with the 3 diets. Doppler ultrasound measurements (caudal artery area, heart rate, and flow rate) and blood samples for determination of serum prolactin were collected during the adjustment period (d 4, 5, and 7) to determine baseline measures, and during the experimental period at 3, 27, 51, 75, 100, 171, and 195 h from initial feeding of the diets. Statistical analyses compared proportionate differences between baseline and responses during the experimental period. Prolactin concentrations for the E- diet during the experimental period were similar to baseline concentrations, and Doppler measures were sporadic. Prolactin concentrations for the E+ and E+E- diets were less (P < 0.05) by 27 h and 51 h, respectively, and remained decreased until 195 h after initiation of diets. Caudal artery area for the E+ diet was less (P < 0.01) between 27 and 171, and caudal artery area for the E+E- diet was less (P < 0.01) between 51 and 99 h. Reductions in heart rate with the E+ diet were only detected (P < 0.05) at 27, 99, and 171 h; no changes in heart rate were observed the E+E- diet. Blood flow rates for E+ and E+E- diets declined after 51 h, but increased to the baseline by 99 h for the E+E- diet and by 171 h for the E+ diet. Results indicated that reductions in blood flow rate through the caudal artery occur by 51 h after consumption of either low or high ergot alkaloid concentrations, even though vasoconstriction and heart rate responses were more sensitive to the higher alkaloid concentration. Doppler ultrasonography is a method to potentially establish threshold toxicity levels for the ergot alkaloids.