EFFECT OF ERGOTAMINE AND ERGONOVINE ON THERMAL REGULATION AND CARDIOVASCULAR FUNCTION IN CATTLE

Research was conducted to determine whether individual ergot alkaloids could induce signs of fescue toxicosis. Nine Angus heifers received s ingle i.v. injections of ergotamine tartrate, ergonovine maleate, and saline vehicle in a simple cross-over design. Each heifer received a d ifferent compound each week and all treatments during the study. Physi ological traits measured 15 min before and 30, 60, and 90 min after tr eatment were respiration rate, rectal and skin temperatures, systolic and diastolic pressures, and heart rate. Blood samples were collected 5 min before and 105 min after treatments to assess plasma prolactin c oncentrations. Heifers were on a fescue-free diet in drylot. Ambient t emperature averaged 35 degrees C during data collection. A treatment x time interaction existed (P < .05) for respiration rate and prolactin concentrations. Ergot alkaloids altered (P < .05) all traits across t ime, except rectal temperature. Heifers under the influence of ergot a lkaloids exhibited significantly lower skin temperature, heart rate, a nd prolactin and had higher respiration rate and blood pressure. Resul ts indicated that individual ergot alkaloids administered i.v. induced signs of fescue toxicosis in cattle.