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Fescue foot: assay of extracts and compounds identified in extracts of toxic tall fescue herbage

Garner, G.B., Cornell, C.N., Yates, S.G., Plattner, R.D., Rothfus, J.A., Kwolek, W.F.
Journal of animal science 1982 v.55 no.1 pp. 185
cattle, goats, toxicity, Festuca arundinacea, plant extracts, fractionation, toxic substances, fescue toxicosis, bioassays, foot diseases, hooves, signs and symptoms (animals and humans), poisonous plants, forage, Missouri
The specific compound(s) that produces fescue foot in cattle grazing tall fescue (Festuca arundinacea) remains unidentified. The study further defines the chemical nature of the toxicant(s) within the anion fraction on an 80% ethanolic extract of toxic tall fescue. By combining the bovine intraperitoneal (ip) assay with videothermometry and ion exchange chromatography, and gas chromatography with mass spectrometry, the following compounds were identified and tested in the toxic fraction: lactic, glycolic, succinic, glyceric, quinic, shikimic, pyroglutamic, pipecolic and malic acids, along with 3-deoxyribo-hexono-1,4-lactone. While some signs of fescue foot were noted, e.g., reddening of the coronary band area when mixtures of organic acids were injected, there was neither a decrease in coronary band temperature nor the appearance of lameness. Although goats showed none of the more significant clinical signs of fescue foot, they did show a skin temperature response to fractions that had previously reduced coronary band temperature values in cattle. Goats may be a suitable assay animal for testing forage extracts via the ip injection-videothermometry technique.