A Holistic Approach to Understanding Fescue Toxicosis: A Path to Drug Therapy?

Undoubtedly, if you have followed fescue toxicosis research developments you have seen the term “ergovaline” prominently in the publications as to the toxin causing fescue toxicosis.  Ergovaline is a chemical that belongs to a specific group of toxins called “ergot alkaloids”.  A research team from the University of Georgia (UGA), Emory University, and the University of Wisconsin are investigating how toxic tall fescue affects the body chemistry and the microorganisms found in the rumen and lower gut of steers.  Their research has shed light as to which toxins are circulating in the blood and plasma, and subsequently excreted in urine.  Their research has been published in highly regarded research journals with stringent review processes that guarantee the research was conducted in a scientifically correct process and appropriately interpreted to reflect the research findings. 

The results of their research has indicated there are three ergot alkaloid toxins that cause changes in the body chemistry of steers grazing toxic tall fescue, none of which were ergovaline.  Each toxin causes unique changes in the body chemistry, indicating that each has a unique way of attacking the body and causing poor livestock performance.  Since each of the toxins has a different way of attacking the body, drug therapy will be more difficult than if there were only one toxin causing the disorder.  This is likely why drug therapy for fescue toxicosis has been elusive.  Furthermore, the toxins cause a change in the microbial populations of the gut; the bacteria and fungi upon which ruminant livestock depend to digest the forage they eat.  Both the body chemistry and the microbial effects of the toxins on the grazing animal change with environmental conditions during the progression from summer to winter and vice versa, complicating the toxicosis scenario even more. 

An attendee of a Novel Tall Fescue Renovation Workshop looks through a microscope to view the endophyte in a fresh tall fescue sample. Microscope and picture provided by Carolyn Young, Noble Research Institute

These research findings are a major step in better defining why the toxins in tall fescue cause poor animal performance.  However, the research indicates that fescue toxicosis is much more complex than previously thought and will take years before drug therapy will be available, if at all.  In the meantime, the best remedy for eliminating fescue toxicosis is to re-seed pastures with non-toxic endophyte-infected tall fescue varieties using the methods supported by the Alliance for Grassland Renewal.

The journal articles listed below can provide further detailed information on the summarized research.

Mote, Ryan S., et al. “Metabolomics of fescue toxicosis in grazing beef steers.” Food and Chemical Toxicology 105 (2017): 285-299.

Mote, Ryan S., et al. “Response of beef cattle fecal microbiota to grazing on toxic tall fescue.” Applied and environmental microbiology 85.15 (2019): e00032-19.

Mote, Ryan S., et al. “Toxic tall fescue grazing increases susceptibility of the Angus steer fecal microbiota and plasma/urine metabolome to environmental effects.” Scientific reports 10.1 (2020): 1-17.

Mote, Ryan S., and Nikolay M. Filipov. “Use of Integrative Interactomics for Improvement of Farm Animal Health and Welfare: An Example with Fescue Toxicosis.” Toxins 12.10 (2020): 633.

~ Nick Hill, Agrinostics Ltd. Co.


The Alliance for Grassland Renewal is a national organization focused on enhancing the appropriate adoption of novel endophyte tall fescue technology through education, incentives, self-regulation and promotion.  For more resources or to learn more about the Alliance for Grassland Renewal, go to www.grasslandrenewal.org

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