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Minimizing the risks of fescue toxicosis in cattle

Fast facts

  • Avoid grazing seed heads of Kentucky 31 fescue
  • Keep plants in vegetative state through good grazing management
  • Not over-fertilizing with nitrogen can help reduce toxin concentration

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FAYETTEVILLE, Ark. -- Grazing fescue before it goes to seed and providing plenty of water and shade during the summer can help ranchers minimize the effects of endophyte-infected fescue forage, said Dirk Philipp, assistant professor for the University of Arkansas System Division of Agriculture.

Endophytes are fungi live in some fescue varieties, such as Ky-31. The endophytes help make the grasses resistant to drought, insects and diseases and can also withstand heavy grazing. However, grazing on these endophyte-infected fescues can lead to a host of symptoms including fescue toxicosis, which squeezes off blood supply to the extremities.

Toxin concentrations are highest between May and October, and because the endophytes concentrate in the seeds, “This means start grazing early to keep plants from going into the reproductive phase,” Philipp said. “Grazing management requires diligence; given the large proportions of fescue pastures on most farms, some sort of advanced grazing management is necessary.”

When cutting fescue for hay, do so before seed heads develop.

“Cutting hay will be best at boot stage,” he said. “If producers wait till June, then seeds will have already developed.”

While options include re-establishing pastures into a friendly endophyte fescue, “this can be expensive and is a long-term solution that requires careful planning,” he said.

In summer, when symptoms of toxicosis -- including elevated body temperatures -- are most likely, Philipp recommends:

  • Providing sufficient amounts of water for cattle to regulate body temperatures,
  • Make sure that cattle have shade in their paddocks or pastures as well; with summer temperatures relatively high during Arkansas, this is necessary to alleviate toxic fescue effects such as elevated body temperature.

“Shades can be built relatively inexpensively, or paddocks can be set up in a way that natural shade is available like large trees, high brush rows, etc.,” he said.

Philipp offers other options for the next few months, including:

  • Establish a summer annual grass such as pearl millet or sorghum-sudangrass to take pressure of the fescue and reducing toxicity, while providing forage diversity, but watch out for high nitrate rates in pearl millet and prussic acid in sorghum-sudan species.
  • There is usually a large forage gap anyway during summer, so planting a summer forage crop make economic sense

Another key to maintaining the health of livestock is being sure not to over-fertilize with nitrogen, because it will increase toxin concentrations in plants. 

  • Excess N can also result from liberal poultry litter applications.
  • Always fertilize by soil test report.

For more information about livestock production, visit or

The Cooperative Extension Service is part of the University of Arkansas System Division of Agriculture and offers its programs to all eligible persons regardless of race, color, national origin, religion, gender, age, disability, marital or veteran status, or any other legally protected status, and is an Affirmative Action/Equal Opportunity Employer.

By the Cooperative Extension Service
UofA Division of Agriculture

Media Contact: Mary Hightower
Dir. of Communication Services
U of A Division of Agriculture
Cooperative Extension Service
(501) 671-2126

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