Superovulatory response and embryo viability of Nelore donors undergo the pre-treatment with Bovine Somatrotopin Recombinant (rbST)

Abstract

The purpose of this study was to evaluate the association of two continuous doses of Recombinant Bovine Somatotropin (rbST), in a protocol of superovulation on the quantity and quality of embryos produced and to evaluate the pregnancy rate of embryos from donors treated with the rbST. Six donors were used divided into three experimental treatments. The first, treatment I (TI), received a dose of 500mg of rbST on day 0 of the protocol of synchronization of follicular wave; the second, treatment II (TII), received two doses of 500mg rbST, the first dose 14 days before the start of the protocol and the other on the start of the protocol and the third, treatment zero (T0), served as control. The means number of structures collected, viable embryos, embryo viability rate, stage of development and embryo quality did not differ significantly between treatments (P>0.05). The pregnancy rates of recipients were: TI = 55,0% (22/40), TII= 60,0% (27/45) and T0 = 34.4% (11/32). There were significant difference between T0 and TII. It is concluded that the rbST improved the pregnancy rate of embryos from donors treated with rbST 14 days before the start of the protocol and the day of starting treatment.