Zeranol and Dietary Protein Level Effects on Live Performance, Carcass Merit, Certain Endocrine Factors and Blood Metabolite Levels of Steers

Abstract

Thirty-Six steers were utilized to test the effects of zeranol implants and dietary protein level on live performance, carcass merit, certain endocrine factors, and blood metabolite levels. The cattle were weighed and bled on days 84, 139 and 169. The blood samples were assayed for serum GH and insulin, and for plasma urea nitrogen and glucose levels. Wet and dry pituitary, thyroid and adrenal weights were taken. Various carcass characters, including taste panel evaluation, were studied. Zeranol-implanted cattle, over the 169-day trial, gained significantly (P<.05) faster (7.8%) than non-implanted steers (1.24 vs. 1.15 kg/day). No significant differences were noted for daily gain due to protein level. A greater cooking loss was the only significant (P<.05) difference noted between implanted vs. control groups for carcass or palatability-related characters. However, zeranol-treated low-protein steers did have a greater percent hindquarter (P<.05) than their respective controls. Low protein level steers had significantly (P<.05) less subcutaneous fat than did 12.5% groups and higher cutability than did 11.0 and 12.5% groups. Also noted were significantly (P<.05) lower serum insulin levels in the low vs. high protein level steers. Implanted steers had significantly (P<.05) greater serum GH levels. Copyright © 1973. American Society of Animal Science . Copyright 1973 by American Society of Animal Science