Performance of cows in the lactation following rbST treatment

Abstract

The first 305-2×-ME lactation record (after 45 days in milk) projected by the DHI program in 28 cows was not different from their first projected lactation record in a previous lactation in which recombinant bovine somatotropin (rbST) injections were begun by the 90th day of lactation. These results suggest when rbSTtreated cows are fed and managed properly during lactation and the dry period, no negative effect of rbST or so-called "burn out" occurs.