Fungal endophytes modify plant-herbivore interactions by producing toxic alkaloids that deter herbivory. However, studies have neglected the direct effects herbivores may have on endophytes. Antifungal properties and signalling effectors in herbivore saliva suggest that evolutionary pressures may select for animals that mitigate the effects of endophyte-produced alkaloids. Here, we tested wheth...

• Climate change (altered CO(2) , warming, and precipitation) may affect plant-microbial interactions, such as the Lolium arundinaceum-Neotyphodium coenophialum symbiosis, to alter future ecosystem structure and function. • To assess this possibility, tall fescue tillers were collected from an existing climate manipulation experiment in a constructed old-field community in Tennessee (USA). Endo...

Epichloë fungal endophytes of cool season grasses are well-known to produce a range of alkaloids of benefit to the host. Some of these compounds are advantageous to agriculture due to qualities that promote pasture persistence (e.g., the loline class of alkaloids confer insect protection) while others are detrimental to the well-being of grazing livestock. The ergot alkaloids (e.g., ergovaline)...

Two experiments were conducted to evaluate the influence of a yeast-derived cell wall preparation (YCW) on forage intake and digestibility, ruminal fermentation characteristics, serum prolactin and prolactin stores, and milk production in beef cattle consuming high-alkaloid tall fescue straw. In Exp. 1, 16 ruminally cannulated Angus x Hereford steers (200 +/- 6 kg of BW) were blocked by BW and ...

Ergot alkaloids are hypothesized to cause vasoconstriction in the midgut, and prior exposure may affect the vasoactivity of these compounds. The objectives of this study were to profile vasoactivity of ergot alkaloids in bovine mesenteric artery (MA) and vein (MV) and determine if previous exposure to endophyte-infected tall fescue seed affected vasoactivity of ergocryptine (ERP), ergotamine (E...

Tall fescue (Lolium arundinaceum) toxicosis research is often complicated by a reduction in intake of infected forage or seed, making treatment comparisons difficult. This study was conducted to develop a fescue toxicosis model that would allow for variations in DMI without altering the quantity of alkaloids consumed over the course of the experiment. Ground tall fescue seed and a tall fescue s...

Previous research has indicated that serotonergic and α-adrenergic receptors in peripheral vasculature are affected by exposure of cattle grazing toxic endophyte-infected (E+; Epichlöe coenophialia) tall fescue (Lolium arundinaceum). The objective of this experiment was to determine the period of time necessary for the vascular effects of ergot alkaloids to subside. Two experiments were conduct...