Isoflavone Containing Legumes Mitigate Ergot Alkaloid-Induced Vasoconstriction in Goats ( Capra hircus ).

Ergot alkaloids produced by a fungal endophyte that infects tall fescue ( Lolium arundinaceum ; (E+ TF) can induce constriction of the vasculature in ruminants, resulting in "fescue toxicosis". Legumes contain isoflavones that have been demonstrated to prevent and reverse E+ TF vasoconstriction. Several legumes are conventionally utilized in ruminant production, but can vary in both isoflavone concentration and composition. A feeding study was conducted to determine if isoflavone supplementation via red clover ( Trifolium pratense ), white clover ( Trifolium repens ), or soybean ( Glycine max ) meal can alleviate vasoconstriction when wether goats were challenged with E+ TF seed. The basal diet was chopped grass hay ad libitum. Carotid luminal areas were obtained pre- and post-ruminal infusions of E+ TF seed (15 µg kg BW -1 ergovaline + ergovalanine ± red clover, white clover, or soybean meal at 2.61 mg kg BW -1 ). When goats were challenged with E+ TF seed, the mean carotid luminal areas decreased by 56.1% ( p < 0.01). All treatments were able to partially mitigate vasoconstriction, with red clover being the most effective (+39.8%), and white clover and soybean meal eliciting an intermediate response (+30%, p < 0.01). Results indicate that legumes can relax vasoconstriction in goats consuming ergot alkaloids, despite differences in isoflavone profile and concentrations.