| Three experiments were conducted to investigate the effects of active immunization against somatostatin (SS) on, (1) the lactational performance of ruminants, (2) growth hormone (GH) secretion and metabolism and (3) the relationship between immunization, plane of nutrition, GH and somatomedin C (SmC) metabolism. In experiment (Exp.) 1, 12 lactating Nubian dairy goats (47 kg) were divided between immunized (I) (biweekly injections of SS-human serum globulin conjugate for 16 wk) and control (C) groups, which received globulin alone. Antibody titer, milk yield, constituent secretion and feed efficiency were measured. Immunization against SS did not affect milk or milk constituent yield, feed efficiency, temporal or GRF-challenged GH levels. In Exp. 2, the response of I and C steers which had been previously immunized for 12 wk, as in Exp. 1, to graded intravenous doses of GRF (0, 25, 50 or 100... |
