Poultry Litter and Its Chemical Equivalent Can Affect Ergot Alkaloid Concentrations in Tall Fescue

Most pastures of tall fescue [Lolium arundinaceum (Schreb.) Darbysh] host a fungal endophyte, Neotyphodium coenophialum [(Morgan-Jones and Gams) Glenn, Bacon, and Hanlin comb. nov.]. The common strain of this endophyte produces ergot alkaloids that cause fescue toxicosis. This research was conducted to determine if fertilizer rate and form (organic or inorganic) would affect ergot alkaloid concentrations in endophyte-infected tall fescue. Poultry litter rates of 0, 2, 4, and 8 tons/acre and equivalent rates of chemical N-P-K fertilizer were applied in 2003-2004. Plants were clipped in June 2004, 2005, and 2006, and herbage samples analyzed for ergot alkaloid concentrations. Total ergot alkaloid concentration was not affected by fertilizer form or rate. However, ergovaline was affected by both in 2004, as concentrations in poultry litter-treated tall fescue averaged 25% less than that in the chemical NPK fertilizer-treated tall fescue. Also, ergovaline concentrations were lowest in tall fescue receiving low rates of fertilizer in 2004 when concentrations were averaged across fertilizer forms. The effects of fertilizer form and rate in only the first year indicated the lack of a carryover effect of fertilizer application on alkaloid production. Producers may reduce toxin levels by using poultry litter instead of chemical fertilizer and by applying low rates.