When tall fescue is analyzed for its nutrient content, it is comparable in quality to other cool-season grasses (Bowman, 1990). However, cattle performance when consuming tall fescue has been erratic. Animals do not graze it readily during the summer months. Some of this reduced summer palatability is associated with the presence of a fungus in the plant (endophyte). Symptoms of fescue toxicosis can include decreased intake, reduced growth rate, rough hair coat, excessive salivation and urination, increased body temperature and respiration, decreased milk production, and impaired reproductive performance (Stuedemann and Hoveland, 1988). Hot temperatures in the summer may aggravate these symptoms, and cattle will generally spend more time standing in ponds and shade, resulting in less time spent grazing. Sometimes foot rot may be confused with fescue foot (Kilgore et al., 1980) because, in the early stages, both have heat and swelling in the lower limbs. However, foot rot normally has swelling and inflammation between the toes.
Animal health problems associated with endophyte-infected stands occur primarily in the summer when animals are under heat stress. The toxin produced by the fungal endophyte is less concentrated in leaf tissue than in the seedheads and stems, so the amount of toxin consumed in the fall is less than in the spring and early summer. The cooler temperatures in the fall and winter reduce the heat stress problems associated with endophyte-infected fescue.
The results of testing tall fescue samples throughout the United States indicate that close to 90 percent of tall fescue pastures have some level of endophyte-infection (Bacon and Siegel, 1988). A rule of thumb often used is that cattle gains will be reduced by 0.1 lb/day for every 10 percent increase in the level of endophyte in tall fescue.
The endophyte is transmitted only through tall fescue seed, and storing seed for 18 to 24 months before use will kill the endophyte. However, germination drops and seedling vigor is reduced after lengthy seed storage. Currently there are nocommercially acceptable chemical methods to get rid of the endophyte in either live plants or seed (Bacon and Siegel, 1988). Therefore, cattle producers must be aware of the available strategies to overcome the effect of endophyte-infected tall fescue. Low-endophyte and endophyte-free tall fescue seed is readily available from most seed suppliers.