Ergot Alkaloid Concentrations in High- and Low-Moisture Tall Fescue Silage

Ergot alkaloids are mycotoxins found in foods and forage crops, including common tall fescue [Lolium arundinaceum (Schreb.) Darbysh. = Schedonorus arundinaceus (Schreb.) Dumort.], which hosts a fungal endophyte. The objective of this study was to determine changes in ergovaline and total ergot alkaloid concentrations in tall fescue silage produced at high moisture (650 to 680 g H2O kg(-1)) and low moisture (340 to 400 g H2O kg(-1)). The study was conducted on endophyte-infected pastures of tall fescue in northern and southern Missouri. Tall fescue was clipped after seedhead emergence but before anthesis, wilted to high or low moisture, baled, and wrapped. After >100 d of ensiling, bales were cored and samples analyzed for ergovaline and total ergot alkaloid concentrations. Ergovaline concentration decreased (P < 0.05) during ensiling at both locations and moisture levels, and the decrease ranged from 24 to 58%. In contrast, total ergot alkaloid concentrations increased during ensiling in high moisture silage in northern (P < 0.10) and southern (P < 0.05) Missouri but did not change in low moisture silage. The opposing responses of ergovaline and total ergot alkaloids offer partial explanations for differences reported in studies involving tall fescue silage. These responses also caution against recommendations to ensile tall fescue to reduce toxins because one analyte indicates detoxification is possible, while the other analyte does not.