Location: Forage-animal Production ResearchTitle: Tackle fescue toxicosis with spring strategies Author
Submitted to: Progressive Cattlemen
Publication Type: Popular Publication
Publication Acceptance Date: 1/25/2011
Publication Date: 3/22/2013
Citation: Aiken, G.E. 2013. Tackle fescue toxicosis with spring strategies. Progressive Cattlemen. Pgs. 26-27. Interpretive Summary: Tall fescue is a cool-season perennial grass that is productive and well adapted to the soils and climate in a region of the USA commonly referred to as the “fescue belt”. The grass has a real advantage in that it is persistent under low management, which has been attributed to a fungal endophyte that infects most fescue plants and produces alkaloids that impart tolerances to heat, drought, and grazing stresses. Unfortunately, the endophyte also produces ergot alkaloids that can induce a toxicosis in cattle. Symptoms of “fescue toxicosis” are elevated body temperature and respiration rate, rough hair coats during the summer months, hormonal imbalances, and a reduction in dry matter intake. Cow herds grazing endophyte-infected tall fescue can have reduced calving rates, milk production, and weaning weights. Average daily gains of stocker calves grazed on endophyte-infected tall fescue are typically very low, particularly in warmer temperatures and humidity when elevated body temperatures adversely affect forage intake. Nutrient deficiencies from low intake by cattle exhibiting signs of toxicosis are also of concern. Overseeding tall fescue with clovers or feeding byproduct feeds can Fescue toxicosis can be alleviated by planting a tall fescue that is infected with a nontoxic novel endophyte, but greater intake by cattle grazing novel endphyte-infected tall fescue will require the use of best grazing management practices.
Technical Abstract: Understanding times of the year when pastures are most toxic can be useful in developing management approaches to alleviate or reduce the severity of toxicosis. Content of ergot alkaloids in fescue vary considerably during the growing season, with the trends generally following the seasonal growth distribution of tall fescue. Ergot alkaloids increase in the plant with active grass growth in the spring and peak in late June when seed has been set and matured. Ergot alkaloids decline during the summer slump in fescue growth, but increase in the fall as active fescue growth occurs. Management approaches can be used to alleviate fescue toxicosis or reduce the severity of the malady to provide some dilution of ergot alkaloids in the diet and to boost dry matter intake and diet quality. Cow-calf producers can implement creep feeding or creep grazing of higher quality, nontoxic forages to increase weaning weights on toxic fescue pastures. Fescue toxicosis can be alleviated by planting a tall fescue that is infected with a nontoxic novel endophyte, but greater intake by cattle grazing novel endphyte-infected tall fescue will require the use of best grazing management practices. These management approaches to alleviating or reducing the severity of toxicosis will be discussed.