Updated 2024
Most Missouri fields are populated by Kentucky 31 tall fescue, a variety infected with a toxic endophyte (often designated E+).
E+ tall fescue can be toxic to cattle when concentrations of the ergot alkaloid, ergovaline, exceed 200 parts per billion; higher concentrations of the toxin have a higher impact on animal health.
Given the prevalence of E+ tall fescue in Missouri and the level of toxicity typical for E+ stands, producers should manage all stands as if they are highly infected to minimize risk to animal health and daily gains.
Understanding where in the plant and when toxicity is at its highest leads directly to management practices to limit the impact of toxic fescue on animal performance.
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