Ask any cattle farmer in southwest Missouri what grass grows in their pasture and a sure-fire answer will almost always be "fescue." Because of the amount of fescue that grows in the Ozarks, endophytes prevalent in fescue pose many problems.
In the mid-1970's scientists discovered an endophytic fungus that can grow within tall fescue.
Vance Hambelton, a University of Missouri agronomy specialist with Ozark County Extension, explained the condition. “Fescue toxicosis is caused by Acremonium coenophialum, a mutalistic fungus simply referred to as ‘the endophyte.' The endophyte grows between plant cell walls, and is therefore invisible in the field.” Hambelton explained the endophyte itself is not toxic to cattle, but the compounds it produces are.
Fescue toxicosis is the condition of the cattle after they’ve been infected with the endophyte. “There are four distinct maladies seen in animals eating endophyte infected tall fescue plants. Another is sometimes included," said Hambelton.
1. Fescue foot
2. Agalactia
3. Fat necrosis
4. Fescue toxicosis
5. Reproductive failure (sometimes)
“According to most researchers, the endophyte produces ergovaline, an alkaloid that produces animal symptoms observed in toxic fields and commonly called ‘summer slump.’”
Your cattle may have experienced summer slump in summers past. Vance added that, “Symptoms of the seasonal slump include poor weight gain, low conception rates, high body temperatures, milk production reductions and diarrhea. During the winter, extreme vasoconstriction sometimes causes sloughing off of the tail, hooves/and or ears. These symptoms are usually called fescue foot.”
Fescue toxicosis is prevalent wherever fescue is grown and according to Hambelton, high summer temperatures seem to increase toxic effects. These negative effects can possibly be seen all year if infected fescue is fed continually. Late spring and summer increases the symptoms because of higher temperatures and increased number of seed heads. Vance added that “seed heads and stems contain about four times more toxins than leaf material.”
Hambelton suggested that renovation of infected fields to different forages or a friendly endophyte fescue can really offset harmful effects of toxicosis. "Some fields renovated with warm season grasses can be very beneficial but this can be very expensive and may be prohibitive because of terrain and rocks,” he said.
Hambelton added that rotational grazing, dilution by interseeding other grasses and dilution by overseeding of legumes such as clovers, annual lespedeza and alfalfa can also help combat toxicosis. He suggested supplementing the cattle with grains or by-product feeds and reducing nitrogen fertilization while considering fall fertilization instead.
Fescue toxicosis is damaging to a livestock operation because it can reduce weight gains of the animals and cause reproductive problems (specifically low conception rates).
Prevention efforts and managing techniques and watching cattle closely during the warmer months of the year, can reduce the harmful effects of “the endophyte” in your operation.
