Location: Forage-animal Production ResearchTitle: Efficacy of a Fescue Seed Extract in Inducing Toxicosis in Cattle) Author
Submitted to: International Symposium on Fungal Endophytes of Grasses
Publication Type: Abstract only
Publication Acceptance Date: 4/19/2010
Publication Date: 6/28/2010
Citation: Koontz, A.F., Bush, L.P., Klotz, J.L., Mcleod, K.R., Harmon, D.L. 2010. Efficacy of a Fescue Seed Extract in Inducing Toxicosis in Cattle. International Symposium on Fungal Endophytes of Grasses. p 58. Interpretive Summary:
Technical Abstract: Tall fescue (Lolium arundinaceum) toxicosis research is often complicated by a reduction in intake. This study was conducted to develop a repeatable model that would prevent a reduction in intake altering the quantity of alkaloids present in the animal over the course of the experiment. A tall fescue seed extract was used in a crossover experiment to determine its ability to induce fescue toxicosis. This experiment utilized four growing Holstein steers (BW = 337±24kg) surgically fitted with ruminal cannulas. Steers were maintained on a diet of endophyte free fescue hay fed ad libitum throughout the experiment. Endophyte infected (E+; 5.33 ppm ergovaline) and uninfected (E-; 0.00 ppm ergovaline) KY-31 tall fescue seed was extracted with ethanol, concentrated and lyophilized. Ergovaline concentration of the final extract was 101.75 ppm. Extract was packaged in cellulose paper and ruminally dosed twice daily at 4.4 mg ergovaline/kg BW. Animals were given a two week washout period between treatments. Physiological indicators were measured over 7d at 22°C (d1-3) and 32°C (d4-7). During E+ treatment rate of intake was reduced at 22°C (P < 0.05) and total feed intake was reduced at 32°C (P < 0.05). Core body temperature was lowered at 22°C and elevated at 32°C during E+ dosing (P < 0.05). Skin temperature over the ribs was unaffected by endophyte treatment. Steers dosed with E+ seed had higher respiration rates at 32°C (P < 0.01), and depressed heart rates at both temperatures (P < 0.0001). At 22°C both systolic and diastolic blood pressures were elevated (P < 0.05) with E+ treatment. These physiological alterations are consistent with those reported for cattle grazing or consuming seed from endophyte infected fescue. These data indicate that an ethanol extract of tall fescue seed is efficacious in inducing fescue toxicosis in cattle.