ENDOPHYTE INFECTED FESCUE:

What it is and what to do about it

by

Dan Colling, Land O'Lakes Farmland Beef Technical Support

"Fescue toxicity", "fescue foot" or "summer slump" are names for problems associated with endophyte-infected fescue. The endophyte is a fungus. Endophyte infection estimates are 90% of tall fescue in the U.S. The greatest concentration of the endophyte is found at the base of the leaf sheath and inside the seed. The active ingredient may be one of the alkaloids found in endophyte: pyrrolizidione, diazaphenanthrene or ergot alkaloids.

Animal symptoms of endophyte toxicosis, which will develop within 10-14 days of grazing infected fescue, include depressed ADG (82%), feed intake (39%) and feed efficiency (42%) for growing cattle as compared to growing cattle on endophyte-free fescue (Auburn University work). Growing cattle will gain 0.1 lb./day less than those endophyte-free cattle for every 10% increase in infection. Pregnant cows have lower conception rates (34%; University of Kentucky work), may abort their fetus, or have a retained or extra thick placenta. While cows on infected fescue produce less milk they also lose more weight during lactation. Sheep will show the same general symptoms but the percentages for cattle may not apply. General symptoms include a rough hair coat, excessive salivation, increased respiration rate (above 30 breaths per minute) and body temperature 103-105ºF, and more time spent in the shade and/or standing in water. The term "fescue foot" comes from the gangrenous dermatitis that causes the skin above the hoof to have local heat, swelling and severe pain resting in lameness. In more advanced cases an indented line appears between the hock and claws in cattle. The skin will dry out, harden and slough off. Dry gangrene may also affect the tips of ears or the tail (the tips fall off). These symptoms are much more pronounced in warm weather (over 75ºF) than cool weather.

Recent research at Mississippi State University has given positive results for relief of heat symptoms from grazing fescue. They are currently in their third year of research using Pro Phos 8 TASCO free-choice mineral to supplement grazing cow calf pairs. The research shows Pro Phos 8 TASCO reduces the body temperature between 0.60 and 0.75 degrees in the cows and 1.0 degree in the calves nursing the cows. This does not sound like a big difference but it was enough to change the grazing pattern of the cows. The Pro Phos 8 TASCO supplemented animals would graze longer in the heat of the day than the cows receiving the same mineral without TASCO.

Producers using the TASCO mineral reported their cows only went to the ponds to drink. They grazed instead of just standing in the water to stay cool. The effect was rapid with producers telling us they could see the effect within 3 days of providing the free-choice Pro Phos 8 TASCO mineral.

A different strategy to help lessen the effects of grazing infected fescue stands may be inter-seeded with legumes to help dilute out the infected fescue. Intake of endophyte fescue may also be diluted by feeding grain or by-product feeds so that the endophyte is a smaller proportion of the ruminal contents. Another management tool available is to keep the fescue in the young, vegetative stage through intensive grazing or clipping (which retards maturation of virtually any treated grass or crop). Complimentary grazing of fescue in the cool weather and a warm season grass like big blue stem in the hot weather will also minimize the negative effects of the endophyte.