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.

The objectives of this study were to document the negative effects of endophyte-infected fescue consumption on cow physiological responses after stress challenge and to assess the ability of blessed thistle to ameliorate these responses. Twenty -seven Angus crossbred cows approximately 5-7 years of age and a body weight of (634 ± 80 kg) were equally divided into 3 treatments. Each treatment was divided into 3 replicates, leaving pens of 3 cows per treatment replicate. Each pen was balanced for initial body weight and low age. Each experimental group was randomly assigned to one of three replicates and one of three treatment dietary regimens: control/endophyte-free (EF) fescue, endophyte-infected (EI) fescue, endophyte-infected fescue + blessed thistle supplementation (EIBT). Ergovaline, one alkaloid compound thought to be deleterious in the endophyte-infected fescue metabolites was detected in EI seed analysis performed before the trial commenced. Endophyte-free seed samples were negative for total ergot alkaloids. No treatment interaction was observed for heart rate, body temperature, prolactin and urinary alkaloid analysis rate (P >0.05). A replicate interaction was observed for prolactin (P <0.05). There was an effect of stress point between before and after samples taken on D-1 and D 29 on body temperature, heart rate and cortisol (P <0.05). Results suggest treatments were ineffectual at inducing symptoms of fescue toxicosis. The full capability of blessed thistle to ameliorate symptoms of fescue toxicosis may not be fully represented in this study. Further research and knowledge into the mechanism by which fescue toxicosis impacts health and productivity of livestock is needed to develop sustainable treatment regimens.

The present investigation was designed to investigate the use of blessed thistle (Cnicus benedictus) in amelioration of fescue toxicosis in beef cattle. Twenty-seven crossbred Angus cows were blocked by age and weight into groups of three. Each group (n=9) was then randomly assigned to one of three dietary treatments: endophyte-free (EF), endophyte-infected (EI), or endophyte-infected with addition of cut and stemmed blessed thistle (EIBT). Each group was also randomly assigned to one of three 29-day replicates. Parameters measured during this trial included: urinary ergot alkaloid concentration (ng ergot alkaloids/mg creatinine), body weight (kg), rectal temperature (°C), serum progesterone (ng/ml), and serum prolactin (ng/ml). No effect of treatment (P>0.05) was detected in any of these parameters. A treatment x time interaction (P<0.0001) was observed for progesterone concentrations, likely a result of estrous cyclicity of cows. Results of this study suggest that we were unsuccessful in inducing fescue toxicity in test subjects assigned to EI and EIBT treatments. Minimal dietary ergovaline (1.72 μg kg-1) and cool ambient temperatures (-6.7°C to 23.3°C) likely contributed to this inability. Data from this research do suggest, however, that C. benedictus can be successfully incorporated into cattle diets. Further research will need to be performed to fully elucidate what, if any, benefits blessed thistle can have in the treatment of fescue toxicity.