Effect of Bovine Somatotropin on the Lactational and Reproductive Performance of Lactating Dairy Cows - a Review

Bovine somatotropin (bST) increases milk production in dairy animals. The maximum increase in milk production has been observed up to 41%. Somatotropin did not change milk composition significantly. During short-term application of bST, cows mobilized their body-reserves to support the increased milk production. Although DM intake of cows was increased in the long-term applications, however, gross efficiency of production was improved due to larger increase in milk production than DM intake. Somatotropin did not adversely affect the health and reproductive performance of the cows. Repartitioning of nutrients in body-tissue was primarily responsible for the increase in milk-production but defining the exact mechanism by which bST exerted its effect still requires additional research.