Effect of a Prolonged-Release Formulation of N-Methionyl Bovine Somatotropin (Sometribove) on Milk Composition

¹ Northeast Dairy Foods Research Center, Cornell University, Ithaca, NY 14853
² Monsanto Corporation, St. Louis, MO 63167

Forty Holstein cows received bi-weekly injections of prolonged-release formulation of bST, and 39 received bi-weekly injections of excipient, in a study to evaluate the effects of long-term bST administration on milk composition and component production. Injections began at 60 ± 3 d postparnun. Administration of bST increased production of milk and of all measured components. Concentrations of lactose (4.85 and 4.81%), fat (3.76 and 3.67%), total solids (12.57 and 12.44%), SNF (8.83 and 8.75%), casein (2.56 and 2.53%), and true protein (3.13 and 3.08%) were similar in milks from cows receiving bST and excipient, respectively. Percentages of NPN (times 6.38) and total protein were greater in milk from bST-treated cows (.179% NPN and 3.32% total protein) compared with milk from cows injected with excipient (.172% NPN and 3.24% total protein). Use of bST did not change the relative percentages of -casein, ß-casein, casein, ß-lactoglobulin, -lactalbumin, or casein proteolysis products. A cyclical pattern of milk production, component production, and composition within each 14-d injection interval was observed. This suggests that a diminishing amount of bST was delivered during the latter third of each injection interval. There were no effects of bST on milk composition that would be of any practical significance to dairy product manufacturers or consumers.

Key Words: somatotropin • milk composition • milk proteins

Submitted on October 8, 1991
Accepted on March 9, 1992

This article has been cited by other articles:

				T. D. ETHERTON and D. E. BAUMAN Biology of Somatotropin in Growth and Lactation of Domestic Animals Physiol Rev, July 1, 1998; 78(3): 745 - 761. [Abstract] [Full Text] [PDF]