Author
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Aiken, Glen |
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Submitted to: Cow Country News
Publication Type: Popular Publication Publication Acceptance Date: 5/25/2015 Publication Date: 6/1/2015 Citation: Aiken, G.E. 2015. From the Lab Bench: Why Control Tall Fescue Seed Heads?. Cow Country News. Pgs. 34-35. Interpretive Summary: Tall fescue is a cool-season perennial grass that is utilized for forage on approximately 35 million acres of the USA; however, toxic ergot alkaloids produced by the endophyte that infects most plants of tall fescue cost the U.S. cattle industry approximately 1 billion dollars per year in lost production. Cattle selectively graze seed heads of endophyte-infected tall fescue, which is a problem because the seed heads are the most toxic plant part. Seed heads can be controlled in tall fescue pastures by either mowing or application with herbicides that contain the active ingredient, metsulfuron. Our research has shown that cattle performance and body condition are enhanced by eliminating the seed heads as a source of toxic alkaloids and by maintaining stands in a vegetative, nutritious stage of growth. Controlling seed heads of tall fescue can serve as a management tool for cattle producers that need to enhance cattle performance and well-being on toxic tall fescue. Technical Abstract: A column was written to discuss controlling emergence of tall fescue seed heads for improving cattle performance and mitigation of fescue toxicosis. Cattle selectively graze seed heads of tall fescue soon after they emerge from the “boot,” which is a concern because seed heads can contain high concentrations of toxic ergot alkaloids. The most toxic ergot alkaloid, ergovaline, is generally in concentrations ranging from 1.0 to 6.0 mg/kg dry matter, and signs of fescue toxicosis can be exhibited with ergovaline concentrations as low as 0.3 parts per million. Our research has demonstrated that cattle start grazing fescue seed heads well before the seeds are mature and contain high amounts of soluble carbohydrate that likely enhance palatability. Seed heads can be controlled by either mowing or using herbicides that contain the active ingredient, metsulfuron. Average daily gains and body condition of steers grazing chemically seed head suppressed fescue have consistently been greater, and the cattle grazing seed head suppressed pastures were less affected by fescue toxicosis than those grazing unsuppressed fescue pastures. Controlling toxic seed heads of tall fescue has potential as a management tool for enhancing production of stocker cattle or developing replacement heifers on toxic tall fescue pasture. |
