Date of Graduation

Spring 2011

Degree

Master of Natural and Applied Science in Agriculture

Department

College of Agriculture

Committee Chair

Gary Webb

Keywords

horse, fescue, ergovaline, ergotamine, exercise physiology

Subject Categories

Agriculture

Abstract

The objective of this study was to examine the effects of tall fescue seed infected with both ergovaline and ergotamine on post exercise recovery of horses subjected to an anaerobic standard exercise test (SET) under hot, humid conditions. Ten quarter horses were selected then paired by body weight (BW), age, and skill level and randomly assigned to either group A or group B that were fed a diet which contained either (E+) or was free of (E-) ergot alkaloids for a 35 d period (P1). Then groups were switched to the opposite diet for the second 35 d period (P2). The E+ diet contained 8.2% seed resulting in 132 ppb ergovaline and 275 ppb ergotamine. Horses were ridden 5 d per week. During wks 3 and 5 (P1) and wks 8 and 10 (P2), horses were subjected to a standard exercise test (SET) designed to obtain a maximal heart rate (HR) (& 150 bpm). During the SET, HR exceeded 150 bpm after the first set of 10 turns and values for lactate (LA) 1 min post SET averaged 10.18 mmol/L, thus confirming horses performed above the anaerobic threshold. A difference among horses was observed for LA, HR, respiratory rate (RR), and rectal temperature (RT) (P & 0.05). Treatment had no effect on RT or LA at any time measured. Heart rates at the end and 1 min post SET were unaffected by seed treatment. When horses consumed E+ diets, HR were lower at rest, during the SET, and at both 5 and 10 min of recovery (P & 0.05). Respiration rates did not vary by treatment at rest or 1, 5, and 10 min post SET, but was higher for the E+ treatment at 30 and 60 min post SET (P ≤ 0.006). Consumption of ground fescue seed caused horses to expend more respiratory effort due to peripheral vasoconstriction as was indicated by lower HR's.

Copyright

© Susan Rachel Demster

Campus Only

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