In the late 1970's fescue toxicity was associated with the presence of an endophyte (internal fungus) in the grass. We have since learned that it is also responsible for fat necrosis (accumulation of fat masses in the abdomens of cattle) and fescue foot (a gangrenous condition of the body extremities of cattle, most commonly the rear feet).

Either fat necrosis or fescue foot can cause important economic losses for a cattle producer, but are relatively rare. However, fescue toxicity is a common problem estimated to cost Alabama beef producers over $20 million annually. Fescue toxicity also affects other types of grazing animals, including causing foaling problems and poor milk production in mares.

Unfortunately, the variety ‘Kentucky 31,' which makes up most of our fescue acreage, is almost always infested with this fungus. Strategies developed for reducing or eliminating the problems caused by the fungus include avoiding the fungus toxins, diluting the toxins by substituting other feeds or forages for toxic fescue, or planting fungus-free fescue.

Insertion into fescue of what scientists refer to as “novel endophytes” is the most recent strategy developed. This term refers to special strains of the fungus that do not produce toxins, but that do impart pest resistance and stress tolerance to fescue plants. (The problem with fungus free fescue, at least in our climate, is that it usually does not persist well.)

The first novel endophyte, named “Max Q,” became commercially available in 1999. This fungus strain was identified by a scientist in New Zealand and put into two University of Georgia varieties named ‘Georgia 5' and ‘Jesup.' In 2003, a second novel endophyte named ‘ArkPlus' became available. In this case, the fungus strain was identified at the University of Arkansas and was inserted into a University of Missouri variety named ‘HiMag.'

Animal performance on Max Q has been similar to that on fungus free fescue, and persistence appears to be similar to Kentucky 31. ArkPlus has not been available as long, so less work has been done with it, but initial indications are that it provides animal performance similar to fungus free varieties. Time will tell how persistent it will be. Other novel endophyte-containing varieties will no doubt be available in the future and each will have to stand the test of time with regard to animal performance and persistence.

Novel endophyte fescue requires special seed production and handling techniques and thus the seed is 3 to 4 times more expensive than Kentucky 31. A question that many cattlemen are probably asking themselves is, “Can I afford to plant that high priced novel endophyte seed?”

Here are some facts that might be helpful. As compared to toxic fescue, yearlings grazing novel endophyte fescue usually gain about 0.1 lb/day more for each 10% of fungus infection, which can amount to more than 100 pounds of difference in gain per animal per year. Weaning weights of calves on novel endophyte pastures are generally 40 to 70 pounds higher than those on toxic fescue. Conception rates of cows grazing novel endophyte fescue has been similar to cows on fungus free fescue, which can be 10 to 30% or more higher than toxic fescue. Fescue disorders have not been seen with horses grazing novel endophyte fescue.

Conclusion

Is novel endophyte seed worth the money? For any livestock producer who is committed to planting a new fescue stand, it should be easy to economically justify buying novel endophyte seed. This is true not only for stocker cattle producers or for someone who wants to pasture pregnant mares on fescue, but also for beef cow-calf producers (just do a few calculations on potential increased income using the figures in the previous paragraph).

When it comes to replacing an existing stand of Kentucky 31, there is more than seed cost involved; virtually a year of pasture production will be lost as a result of killing the toxic fescue. However, it still is not difficult for a stocker cattle producer to justify making the change. For a beef cow/calf producer the picture is less clear, but Dr. Curt Lacy and Dr. John Andrae at the University of Georgia recently calculated that reaching the breakeven point on replacing toxic tall fescue would take as little as 1.8 years if conception rates on toxic fescue would otherwise have been lowered from 90% to 66%, or as long as 10.5 years if there was no lowering of conception rates below 90%.