The use of recombinant bovine somatotropin (rbST) in superovulated Holstein donors to increase the number and quality of the embryos was studied. Forty cows were randomly allotted into three groups: control (n=15), treated with 250mg rbST (n=11) and treated with 500mg rbST (n=14) on the 6th day of the oestrous cycle. On the 10th day after estrus the donors were submitted to a superovulatory treatment with 360mg of FSH in decreasing doses, twice-a-day, with 12 hours interval. Along with the 7th application of FSH, 0.5mg of cloprostenol was injected and the donors were inseminated 12, 20 and 28 hours after the onset of estrus. Embryos were collected non-surgically on the 7th day after the 1st insemination. The use of 250 or 500mg of rbST increased (P<0.05) the percentage of viable embryos, but did not alter the recipient pregnancy rate.
embryo; pregnancy rate; somatotropin
