Date Available

12-7-2011

Year of Publication

2008

Degree Name

Master of Science (MS)

Document Type

Thesis

College

Agriculture

Department

Veterinary Science

First Advisor

Dr. Karen J. McDowell

Abstract

Ingestion of endophyte infected (E+) fescue by pregnant mares can cause significant reproductive problems. Plateau® and Cimarron® herbicides suppress fescue while leaving desired forages unharmed. To determine if these herbicides are harmful to pregnant mares, they were allowed to graze pastures treated with Plateau®, Cimarron®, or vehicle carrier. Pregnancies were monitored via ultrasonography, blood chemistry, and hematology. Of the components measured only creatinine differed among treatments over time (P=0.0003) and that increase was only significant in one of four studies.

Two additional experiments were conducted to determine the effect of the herbicides on alkaloids within E+ fescue. A greenhouse experiment utilizing 52 pots of E+ fescue treated with Plateau®, Cimarron®, or nothing was inconclusive, as some alkaloids increased while others decreased. These results indicated that UV light may be required for normal plant death. In a field experiment 12 plots of mixed vegetation were sprayed with the same treatments, and herbicides decreased ergovaline, N-formylloline, and lysergic acid content (P=0.0460, P=0.0324, P=0.0093 respectively). In conclusion, the herbicides did not alter blood components outside physiological norms, but the alkaloids were still present in dying E+ fescue. It may be safest to remove late gestation mares until E+ fescue is completely decayed.

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