Tall fescue (Festuca arundinacea) is the native pasture in most of the central United States. It is also the most abundant and economically important cool season grass in the country. Approximately 688,000 of the country’s 9.2 million horses graze an estimated 35 million acres of tall fescue.

Tall fescue is a coarse grass with broad leaves and prominent veins. It is a good forage for horses, because it is hardy, easily established, tolerates close grazing, stands up to heavy horse traffic, survives drought conditions, and is resistant to weeds, insects and diseases. However, most of the tall fescue is infected with an endophyte (endo = inside + phyte = plant) fungus called Neotyphodium coenophialum (formerly called Acremonium coenophialum) which improves the hardiness of the grass, but has negative effects on the livestock grazing it. There are endophyte-free species of fescue, but they are less hardy and usually end up becoming infected by neighboring native grass.

Research reports show Endo-Fighter^TM is extremely effective at countering the effects of fescue toxicosis in cattle. Because of the success of Endo-Fighter, we’ve had questions about its use in horses. Horses do not have the same effects from endophyte-infected fescue, so our current Endo-Fighter for cattle is not effective in horses. There are some reports of reduced growth and performance of horses fed infected fescue, but those effects are minor compared to the severe effects seen in pregnant mares. If pregnant mares graze infected fescue or are fed infected-fescue hay in the last three months of gestation, they can have lengthened gestation, thickened placental membranes, retained placentas, large foals leading to dystocia or foaling difficulties and lack of milk production. Without treatment, foals from these mares will die, and the mares can also be lost in the foaling process. Because of this, all mares should be removed from infected fescue for the last 90 days of gestation. Remember, mares have an average gestation of 11 months, one week and 1 day, so count from the last cover date to determine expected foaling date.

If symptoms of fescue toxicosis are present in mares, call your veterinarian immediately. A drug called Domperidone, which stimulates normal prolactin and progesterone production, can be administered and will usually counteract the effects and cause mares to begin producing milk. Domperidone should be administered daily for the 30 days prior to foaling and will cost about $75.00 per mare. However, it is still much better to remove mares from the source of infected fescue, which can be pasture, hay, grass clippings or bedding.

In conclusion:

• ADM Alliance Nutrition’s new Endo-Fighter does not work in horses due to species differences between horses and cattle.
   

• Late pregnant mares and their foals suffer the worst effects of infected fescue, so mares must not be allowed to graze on it or be fed the hay during the last 3 months of gestation.
   

• If your customers tell you their mares are having symptoms of fescue toxicosis, tell them to contact their veterinarian for treatment.
   

And, be sure to send them to our HELPLINE at (800) 680-8254 for feeding programs.

For More Information e-mail at AN_EquineHelp@admworld.com

or call toll free
EQUINE NUTRITION HELPLINE
1-800-680-8254
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ADM Alliance Nutrition, Inc. 1000 North 30th Street P.O. Box C1 Quincy, IL USA 62305-3155