University of Arkansas, Fayetteville Division of Agriculture
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Abstract

Ergotamine is an ergot alkaloid associated with fescue toxicosis of livestock who have grazed endophyte-infected fescue. High performance liquid chromatography (HPLC) was used to detect individual or species-specific differences in the metabolism of ergotamine by liver cytochrome P450 of sheep and cattle. Livers were collected from four steers and two sheep. The diet of the steers used in this study consisted of two being fed a grain diet, one steer grazing endophyte-infected fescue, and the final steer grazing endophyte-free fescue. The two lambs were both fed a grain diet. Livers were prepared and examined for the disappearance of ergotamine and its isomer by HPLC analysis. Liver microsomes from cattle appeared to metabolize ergotamine to a greater degree than those from sheep. There were no apparent differences in the metabolism of ergotamine when comparing cattle that grazed endophyte-infected fescue to cattle that grazed endophyte-free fescue. Therefore, diet had no effect on the metabolism rate of ergotamine. This work provides insight into the possible genetic differences between speciesspecific and individual animals. Further study of such differences should improve breeding programs and produce animals that can more effectively tolerate fescue toxins.

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