Articles on forages, animals, and grazing systems
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Extension Forage Specialist
University of Kentucky
Phone: (859) 257-3358
Fax: (859) 323-1952
More than 35 million acres in the country are covered in tall fescue. It is the predominant forage grass in Kentucky and other south eastern states. Tall fescue is often favored for many reasons. This high yielding forage can survive undesirable environmental conditions, such as drought and flood conditions, pests, heavy grazing pressure, and competition from other plants. Fescue can produce full, thick, and healthy stands due to high seed production, germination rates, and seedling vigor. It is also known for its efficient mineral uptake and high tiller growth rate. These attributes allow fescue to thrive in the majority of Kentucky pastures.
Although tall fescue has numerous positive attributes, it has a negative reputation for causing fescue toxicity in livestock. Ergot alkaloids produced by a fungus in the grass are toxic to livestock.
This endophyte fungus can cause reproduction problems, lower gains, fescue foot, increased body temperatures, failure to shed winter coat, and bovine fat necrosis. To eliminate these issues, fescue breeders created an endophyte free variety of fescue. It was quickly discovered that these new varieties did not have the same vigor and stand persistence as the “dirty fescue”. The other benefits that made fescue popular were also reduced. The endophyte was found to be responsible for the plants ability to survive and thrive in undesirable environments. The plant and fungus form a symbiotic relationship where both benefit from one another. The endophyte enhances seeding vigor, tiller growth rate, seed production, mineral uptake, germination rate, drought tolerance, grazing tolerance, and pest resistance.
Currently, many farmers are planting a novel endophyte infected variety of tall fescue. Novel endophytes are non-toxic to livestock but still provide the benefits responsible for the grasses persistence. Some strains of endophytes do not produce the ergot alkaloids which are responsible for the toxicity to livestock. Studies have shown that the performance and health of livestock grazing novel endophyte infected fescue are excellent and there are no signs of the problems that are seen with grazing dirty fescue.
Planting a novel endophyte infected variety of tall fescue can be a great way to diminish fescue toxicity in livestock while keeping the many benefits of grazing tall fescue. One negative of planting these varieties is the higher seed costs. Costs and labor of planting and establishing the new stand should also be considered. Renovating an existing field of dirty fescue can be difficult. It is important to use the best management practices to remove the existing stand and to replant a non-toxic variety. It may be necessary to keep animals off fields to allow adequate establishment time before grazing. Taking all factors into consideration, the pros of renovating current fields with a novel endophyte infected tall fescue can be beneficial to animal performance and economic profit of many pasture based cattle operations.
For farmers who currently graze endophyte infected tall fescue, steps can be taken to reduce fescue toxicity. Determining the level of endophyte toxicity can be a useful tool to prevent animal health and reproduction issues. Seeds or plants can be tested to determine these levels. The Kentucky 31 variety of fescue, which is common in Kentucky pastures, is known to have high levels of toxic endophytes. Using practices to increase growth of other forages in the stand can be used to increase specie availability to dilute out the infected tall fescue. Grazing fescue early in the season can reduce competition and give other plants a better chance to grow. Another way to reduce competition is to cut fescue at a lower height. Applying nitrogen in the summer can increase growth of warm season grasses while cool season grasses, like tall fescue, experience summer slump.
These management practices will increase plant diversity in pastures and can reduce fescue toxicity. Inter-seeding other grasses or legumes into a fescue stand is another way to reduce toxicity problems. Adding a legume can be beneficial to animal health and performance as well as decreasing fescue toxicity complications. Because endophytes are at high levels in the seed heads, keeping tall fescue in a vegetative state or removing seed heads by mowing can be helpful. Feeding non-toxic hay or grain will also reduce toxicity.
Fescue toxicity effects many grass fed cattle as well as cattle fed stored-feed. Poor animal performance can cause economic losses that are devastating for any producer. Talk to your county extension agent to see if using a novel endophyte infected variety of tall fescue may be beneficial on your farm.