Wednesday, November 15, 2006

Ergovaline concentrations in stored tall fescue hay.

Craig Roberts1, Robert Kallenbach2, George Rottinghaus3, Ryan Lock2, Heather Benedict2, and Matt Massie4. (1) 108 Waters Hall, University of Missouri, University of Missouri, Dept. of Agronomy, Columbia, MO 65211, (2) Plant Sciences Division, 108 Waters Hall, University of Missouri, Columbia, MO 65211, (3) College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, (4) Southwest Research Center, University of Missouri, Mt. Vernon, MO 64735

Tall fescue infected with toxic strains of the endophyte, Neotyphodium coenophialum, often contains high concentrations of ergovaline.  Ergovaline, either in its ingested form or via its lysergic acid derivatives, is widely regarded as a primary toxin contributing to fescue toxicosis.  Surprisingly, ergovaline concentrations during haymaking and subsequent storage are neither reported in the research literature nor mentioned in extension recommendations.  This objective of this research was to determine ergovaline concentration in tall fescue hay production and storage.  The research was initiated in 2004 at Mt. Vernon, Missouri, on tall fescue pastures 99% infected with the endophyte. Tall fescue was clipped and sun-cured until moisture levels reached 11.5% and 21.5%.   Tall fescue samples were collected immediately after clipping and at 12-hr intervals throughout curing.  Hay was baled and stored in a covered structure and hay samples collected over the following 18 months.  Samples were stored at – 5 C until processing, at which time they were freeze-dried, ground to 1-mm, and analyzed for ergovaline concentration using near-infrared (NIR) spectroscopy with a reference values obtained by HPLC.  The NIR equation statistics had a mean and standard error of cross-validation of 372 ± 65 mg kg-1 dry matter and a 1 minus the variance ration of 0.90.  Preliminary data show ergovaline concentration in tall fescue decreased by 30% in the first two weeks after clipping, whether or not hay was baled at high or low moisture.  Most of that decrease occurred during the curing process prior to baling.  Concentrations decreased only slightly over the next 17 months.  Final data are presently being collected and analyzed for the second year of production.  This research was partially supported by the USDA Agricultural Research Service through the Dale Bumpers Small Farm Research Center under Agreement No. 58-6227-3-016.