The greatest anti-quality associated with eastern temperature pasture grasses is the result of ergot alkaloids found in endophyte-infected (Neotyphodium ceonophialum) tall fescue (Festuca arundinacea Schreb.) The relationship between the grass and the endophyte is mutalistic with greater persistence and herbage mass as a result of the endophyte. Ergot alkaloids reduce growth rate, lactation, and reproduction in livestock. Significant effects are the result of elevated body temperature and reduced peripheral blood flow such that necrosis may result. Perturbations also occur in a variety of body systems. Planting new pastures with seed containing a "non-toxic" endophyte appears to be a potential solution. Ergotism results from the ingestion of the scelerotia of Claviceps purpurea containing ergot alkaloids found on seed heads. Ergotism resembles the effects of endophyte-infected tall fescue. Endophyte-infected perennial ryegrass (Lolium perenne L.) contains ergot and lotirem alkaloids that result in reduced growth and tremors. Reed canarygrass (Phalaris Anundinacba L.) contains tryptamine, hordenine and gramine alkaloids that reduce growth. Annual ryegrass (Lolium multiplorum L. may contain galls with cornetoxins which result in neurological signs.

Field studies were conducted to examine yield, alkaloid stability, stand survival, and animal toxicity in tall fescue (Festuca arundinacea Shreb.) germplasms, infected with their endemic endophyte [Neotyphodium coenophialum (Morgan‐Jones and Gams) Glenn, Bacon, and Hanlin] and bred for high‐ or low‐alkaloid concentration. Three germplasms selected from endophyte‐infected (E+) ‘Jesup’ for low‐alkaloid and two germplasms selected for high‐alkaloid, along with E+ and endophyte‐free (E−) Jesup, E+ and E− ‘Kentucky‐31’, and E− ‘AU Triumph’ tall fescue were planted at a mountain and a piedmont location in Georgia, and the forage harvested for 3 yr. Yield was calculated and alkaloid concentration was measured. In separate experiments, stand survival of one high‐ and one low‐alkaloid germplasm was assessed in bermudagrass [Cynodon dactylon (L.) Pers.] sod by grazing with beef cattle. Toxicity was assessed on one low‐alkaloid germplasm in lamb performance trials. Yields of the low‐ and high‐alkaloid germplasms were similar to the E+ Jesup cultivar. The low‐ and high‐alkaloid germplasms remained low and high in alkaloids, respectively. The E+ check and the germplasms bred for both high‐ and low‐ergot alkaloid concentration were found to have superior stand survival compared with the E− check, but the low‐alkaloid germplasm had lower stand survival than the E+ check. Lambs grazing the low‐alkaloid germplasm showed weight gain ranking between those on E+ and E− pasture. This study indicates that persistence and alkaloid concentration were stable over environments; however, animal toxicity and the stand reduction exhibited by the low‐alkaloid producing germplasm raises when grazed questions about breeding for reduced alkaloid concentration.