Performance, clinical chemistry, and carcass response of finishing lambs to formulated sometribove (Methionyl bovine somatotropin)

• Published in: Journal of animal science Vol. 72; no. 10
• Main Authors: McLaughlin, C.L. (Monsanto Company, St. Louis, MO.), Hedrick, H.B, Veenhuizen, J.J, Hintz, R.L, Munyakazi, L, Kasser, T.R, Baile, C.A
• Format: Journal Article
• Language: English
• Published: 01-10-1994
• Subjects: AGNEAU; COMPOSICION DE LA CANAL; COMPOSICION DE LA SANGRE; COMPOSITION DE LA CARCASSE; COMPOSITION DU SANG; CORDERO; DESEMPENO; ENGORDE; ENGRAISSEMENT; METHODE D'APPLICATION; METODOS DE APLICACION; SOMATOTROPINA; SOMATOTROPINE
• ISSN: 0021-8812; 1525-3163

Formulated zinc methionyl bST (sometribove, 50, 100, or 150 mg) was administered as a single treatment once every 2 wk or as two equal treatments once/week to evaluate the efficacy of prolonged release delivery of bovine somatotropin (bST) in finishing lambs. Feed conversion during the 6-wk treatment period was improved 9 and 19% in lambs that received treatments once and twice/2 wk, respectively (P 0.05), and the responses to differing doses were similar within a dosing frequency (P 0.05). Carcass muscle:fat ratio indicators generally were affected in a dose-related manner and were independent of frequency of administration. For example, fat thickness was 17, 30, and 42% lower than control in lambs that received 50, 100, and 150 mg of formulated sometribove/2 wk, respectively (P 0.05). Percentages of muscle were higher and of fat were lower with increasing dose of formulated sometribove, but weight of only fat was significantly affected (P 0.05). Clinical chemistry indices of metabolic effects of bST (e.g., circulating bST, IGF-I, insulin, glucose, and urinary nitrogen concentrations) were affected in directions similar to those observed with bST administered by daily injection. The results of this study demonstrate the growth performance and carcass composition advantages of a formulation designed to deliver bST over a 2-wk period