SOMATOTROPIN IN LACTATING COWS - EFFECT ON RESPONSE TO EPINEPHRINE AND INSULIN

Abstract

The dose dependence of plasma nonesterified fatty acids (NEFA) and glycerol responses to epinephrine was determined in lactating cows treated with bovine somatotropin (bST). Also, the effects of insulin on lipolysis and glucose clearance were examined. Lactating cows (190 +/- 24 days postpartum) received daily subcutaneous injections of methionyl bST (40 mg) or excipient during two 12-day treatment periods. Epinephrine challenges (0.1, 0.2, 0.4, 0.8, 1.2, and 1.6 micrograms/kg body wt) were administered intravenously on days 6-11 and an insulin challenge (1 microgram/kg) on day 12. Milk energy secretion increased 55% without any change in voluntary feed intake during bST treatment. Circulati..