Studies on the safety of recombinant bovine somatotropin in dairy cow I. Effects of recombinant bovine somatotropin on mineral composition in milk of dairy cows

γ BST 의 유우에 대한 안정성 연구 I. γ BST가 우유중 미량광물질 조성에 미치는 영향

Effects of recombinant bovine somatotropin$({\gamma}BST)$ on mineral composition of milk were investigated in Twenty-five multiparous Holstein dairy cows. Recombinant BST was administered by two different routes; intramusculary(12.5mg and 25mg/day) and subcutaneously (500mg and 750mg) in sustained-release vehicle every 2 weeks beginning 4 week postpartum and continuing for 7 months. Milks were collected 0,1,2,3,5 and 7 months after beginning of treatments in control and ${\gamma}BST$-administered groups. Mineral composition, such as Ca, Pi, Na, K, Mg, Zn, Fe and Mn, in milk were not affected by the administration of ${\gamma}BST$ regardless of dose and dosage forms. It is concluded from the observations of these experiments that the dose and dosage forms of ${\gamma}BST$ employed in this work might not affect milk mineral composition in dairy cows under the normal sanitary condition and adequate nutrient balance.