According to Craig Roberts, state forage specialist at the Department of Agronomy, University of Missouri, this disease, tall fescue toxicosis, is costing U.S. livestock producers more than $600 million each year. Tall fescue toxicosis is caused by a fungus that lives in tall fescue grass. When the fungus is not present, tall fescue is a highly-nutritional pasture grass.
Tall fescue toxicosis is most easily recognized by grotesque symptoms, such as fescue foot in cattle. Toxicosis is also seen in cattle that fail to shed their winter coats in the summer and display a shaggy, unkept appearance. Some of the most serious symptoms of tall fescue toxicosis, however, are not visible. These include narrowed blood vessels that cause restriction of blood flow, high core body temperature, increased respiration, low heart rate, altered fat metabolism, failure to produce milk, suppression of the immune system, reduced forage intake, and low rate of weight gain. Fescue toxicosis also causes serious reproductive problems, such as low pregnancy rate and birthing difficulty.
"At present, there is no cure for tall fescue toxicosis, but proven management strategies can lessen its effect," said Roberts. Such strategies include replacing toxic tall fescue with cultivars that are endophyte-free or contain beneficial endophytes, interseeding other forages to dilute the toxins, rotating livestock to non-toxic pastures, and ammoniating hay. "These new and old management practices limit the ingestion of toxic alkaloids and improve the health of their livestock and the profitability of their operations," said Roberts.
More on this topic is available in a recently published article from Crop Management, a journal published by Plant Management Network (PMN). A summary of the article can be found at www.plantmanagementnetwork.org/feature/fescue/. The full article is available with a subscription to PMN. Subscriptions to PMN and its journals are available at www.plantmanagementnetwork.org/.
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