The endophyte produces alkaloids beneficial to the grass but detrimental to cattle performance. Fescue toxicosis causes a significant loss of income to the largest segment of the agricultural economy in Tennessee and the United States. Basic mechanisms by which ergot alkaloids reduce cattle productivity are not known, but previous research in this laboratory of treating cattle with ergotamine, an ergopeptine alkaloid, suggests that disrupted endocrine function may be involved. The objective of this research effort was to determine if an ergopeptine alkaloid isolated from EI tall fescue altered plasma concentrations of hormones important to regulating metabolic function.
Metabolism plays a central role in bovine reproduction and growth.
Shifts in metabolic processes could lead to poor nutrient utilization, reduced nutritional status, and a subsequent lowering of performance for traits of economic importance to cattle producers. Cows were treated intravenously with saline vehicle or ergotamine tartrate after one hour of blood sampling in a simple crossover design. Ergotamine significantly increased plasma concentrations of each blood constituent measured, with the exceptions of a significant decrease in plasma insulin and a biphasic rise, then fall, in triglyceride concentrations. These responses correspond with noted poor growth and reproduction. Findings of this study are unique to the current literature and suggest that altered metabolic function and nutrient utilization may be a means by which EI tall fescue hinders cattle performance.