Effects of Zeranol on Blood Metabolites and Hormones in Wether Lambs

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Abstract
Three experiments were conducted to determine the effects of zeranol on blood metabolites and hormones in wether lambs. Intravenous infusion of 0, 1 or 5 mg zeranol in Experiment 1 did not affect serum urea nitrogen, glucose, growth hormone (GH) or insulin. Implantation with 12 mg zeranol in Experiment 2 increased serum GH and insulin, but did not change serum urea nitrogen or glucose. In Experiment 3, wether lambs implanted with 0, 12 or 96 mg zeranol were infused with .5 g/kg body weight of arginine. Clearance rate of the arginine was not affected by implantation. Insulin secretion in response to arginine was not influenced by zeranol implantation. Because arginine failed to stimulate GH release, no conclusions could be drawn concerning GH secretory capacity of the pituitary. In summary, zeranol did not affect serum urea nitrogen or glucose in any experiment. Serum GH and insulin were increased by zeranol implantation but not by zeranol infusion. These data suggest that chronic exposure to zeranol was necessary to stimulate an increase in serum GH and insulin in wethers. Copyright © 1977. American Society of Animal Science . Copyright 1977 by American Society of Animal Science