Effect of two formulations of recombinant bovine somatotropin on milk production and body condition of cattle under intensive management in Peru.

The effect of recombinant somatotropin (rbST) application in cattle has been demonstrated in temperate climate but very limited studies are available in tropical regions. The objective of this study was to compare the effect of the application of two different formulations of rbST on the milk yield and body condition of dairy cattle in a commercial herd under intensive production in Peru. We evaluated the application of 500 mg of active rbST in a zinc sesame oil (ZSO-rbST; n = 44) or vitamin E lecithin (VEL-rbST; n = 45) vehicle while control cows (n = 42) did not receive any application.