PSVI-5 Using Red Clover Extract to Mitigate Tall Fescue Toxicosis

Abstract

Abstract Tall fescue toxicosis is caused by ergot alkaloids produced by the fungus Neotyphodium coenophialum that resides within the majority of the tall fescue plants in the Southeastern and lower Midwestern US. Tall fescue (Festuca arundinacea) toxicosis is estimated to cost livestock producers over $1 billion dollars annually through reduced growth and reproductive performance. Improvements in performance by cattle grazing toxic tall fescue can have substantial economic advantages for livestock producers throughout the tall fescue region. Numerous methods to mitigate tall fescue toxicosis have been tried over the past 60+ years, but a practical solution to this problem has not been discovered to date. Forages used to dilute fescue include clovers which will not compete on much of the marginal sites that tall fescue predominates. As mentioned above, clovers have been used to dilute toxic fescue and have shown to be a good mitigation strategy if the clovers persist. Red clover extract (RCE) has shown promise in the mitigation of symptoms related to tall fescue toxicosis, but effective dosages have not yet been determined to date. Dorper ewe and wether lambs (n = 30, 34 ± 0.97 kg initial BW) were weighed and assigned randomly to one of five diets in a 2-period study. Diets consisted of a positive control of non-toxic tall fescue seed with no RCE (CONT), a negative control of toxic tall fescue seed with no RCE (E+0) and toxic tall fescue seed with RCE supplemented at 0.33 (E+33), 0.67 (E+67), and 1 (E+100) percent of the diet. Fescue seed was mixed with liquid molasses to ensure consumption, and seed, DDGS and RCE was offered at approximately 0800 and 1600 h, and bermudagrass hay was offered for ad libitum consumption. Lambs were housed in individual 1 × 1.5 m pens in an enclosed building where temperature was maintained at 27° C (80° F). The animal had an ad libitum access to water. Each period consisted of a 14-day adaptation period followed by 7 d of total fecal and urine collection. Diets were offered for ad libitum consumption during the first 12 days of each period and then held constant during the remaining 9 days. Dry matter (DM) and organic matter (OM) intake was greater (P < 0.05) from CONT than all other treatments and E+33 was greater (P < 0.05) than E+10 and E+67. Digestibility of DM and OM were greater (P < 0.05) from CONT than all other treatments. By contrast, the diets did not influence (P > 0.05) nitrogen balance, urinary nitrogen losses, fecal nitrogen losses and nitrogen retained. Overall, results demonstrated that RCE inclusion into the diet of toxic tall fescue did not significantly change growth and performance parameters in sheep.