Ergot Alkaloid Concentrations in Tall Fescue Hay during Production and Storage

Abstract

Common tall fescue [Lolium arundinaceum (Schreb.) Darbysh. = Schedonorus arundinaceus (Schreb.) Dumort.] is infected with a fungus that produces ergot alkaloids, a class of compounds associated with fescue toxicosis. The objective of this research was to monitor the change in concentrations of ergot alkaloids from time of clipping through storage of tall fescue hay. A 2‐yr field study was conducted in Mt. Vernon, MO, in which tall fescue was baled at high moisture (204–219 g H2O kg−1 dry matter [DM]) and low moisture (102–112 g H2O kg−1 DM) then stored for 18 mo. Hay samples were collected over the 540‐d period from clipping through storage and analyzed for ergovaline and total ergot alkaloid concentration. Data were analyzed using standard ANOVA procedures and break‐point regression. In both years, ergovaline concentrations decreased sharply within the first month after harvest and gradually over the remaining 17 mo. In three of the four cases, most of the ergovaline disappearance occurred within 3 d after clipping. The final ergovaline concentration remained above 250 μg kg−1 DM, which is still considered toxic to livestock. In the first year, ergot alkaloid concentration followed a pattern similar to ergovaline concentration. In the second year, however, the decrease in total ergot alkaloid was gradual throughout the entire 18 mo. A general recommendation to producers would be to delay feeding toxic tall fescue hay until at least 1 mo after clipping.