Symposium: Tall Fescue Toxicosis

The Fescue Toxicosis Symposium: Introduction to the Proceedings

Glen E. Aiken, Research Animal Scientist, USDA-ARS, Forage-Animal Production Research Unit, Lexington, KY 40546

Fescue Toxicosis was a symposium presented at the 2008 joint meetings of the American Forage and Grassland Council and the Society for Range Management in Louisville, KY. The purpose of the symposium was to: (i) provide updated information on toxic and non-toxic endophyte interactions with herbivores (cattle, horses, and small ruminants); (ii) present new technologies that are being used in studying fescue toxicosis; and (iii) discuss technologies developed to alleviate toxicosis.

Tall fescue (Lolium arundinaceum L.) is a cool-season perennial grass that is the predominant pasture grass in the region commonly referred to as the “fescue belt,” which extends from the lower temperate northeast to the upper subtropical southeast to the lower temperate northeast and west to the eastern fringes of the Great Plains. Its productivity and persistence is attributed to a fungal endophyte (Neotyphodium coenophialum) that imparts tolerances to drought, heat, and grazing. Unfortunately, ergot alkaloids produced by the endophyte can cause fescue toxicosis. The toxicosis syndrome has been well documented to adversely affect calf weight gain and cow reproduction performance. Although it is well understood that ergot alkaloids have a profound effect on the reproductive physiology of mares (e.g., prolonged gestation and poor milk production), it has not been established if ergot alkaloids affect growth and development of colts and fillies. Further, fescue toxicosis research with small ruminants has been limited in comparison to cattle and horses.

A complete understanding of the interactions of ergot alkaloids with biologic mechanisms and processes has eluded us, but research conducted in the last 10 years has substantially added to our knowledge base and is leading to development of technologies that can mitigate the dramatic effects that toxicosis has on livestock production. These research developments were the focus of the Fescue Toxicosis symposium and the papers of these proceedings.