Date of Award


Degree Name

Master of Science


Animal Science

First Advisor

Jones, Karen


Fescue Toxicosis occurs when animals are fed or grazing on Tall Fescue (Festuca arundinacea) syn. (Lolium arudinacea [Schreb]) grass that is infected with the endophytic fungus Neotyphodium coenophialum (Bacon et al., 1977). This disease affects cattle, sheep, and horses causing reduced feed consumption, average daily gain (ADG), and reproductive performance (Hoveland, 2003). The disease is caused by ergot alkaloids within the fungus, which lives in the plant (Hoveland et al., 1980). Fescue toxicosis is a major concern because at least 35 million acres in the United States contain Tall Fescue (Faulkner, 1999); areas impacted include southern Illinois, Kentucky, Tennessee, northern Mississippi, northern Louisiana, Georgia, West Virginia, Arkansas and Missouri and in some areas of the Pacific coast such as Oregon (Roberts et al., 2004). Due to the effects of this disease, producers lose an estimated 609 million dollars per year (Paterson et. al, 1995). The aim of this research project was to determine if the herbal supplement, Blessed Thistle, could be used to counteract the effects of fescue toxicosis in cattle. Eighteen Angus first calf heifers and their calves were divided into three treatment groups (n = 6); negative control fed non-endophyte infected Max Q hay (EN), positive control fed endophyte infected KY-31 fescue hay (E+), or treatment fed KY-31 fescue hay and Blessed Thistle extract (E+/BT). Heifers fed E+/BT diet maintained pretreatment prolactin levels throughout the study. Additionally, the change in prolactin levels E- and E+/BT were not significantly different suggesting a protective effect from the blessed thistle. The change in heifer BCS was insignificant except for the E+/BT group which was significantly different (P = 0.02) before and after. The differences between the calf weights were trending (P = 0.088) indicating the ability of the E+/BT calves to perform similarly to the E- calves. The milk production estimate was insignificant (P = 0.497). The rectal temperatures data indicated a difference at the beginning and end of the study (P < 0.001). However, no differences were detected between treatment groups. These results suggest that Blessed Thistle can ameliorate some symptoms of fescue toxicosis however, further research is needed.




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