299 OVUM PICK-UP USE IN NELORE COWS SUPERSTIMULATED WITH FSH OR eCG

Abstract

The success of reproductive technologies, such as embryo transfer and IVF, greatly depend on the response to superovulation. Using hormonal therapy, it is possible to increase the reproductive rates of beef and dairy cattle for individual and herd treatment. The objective of the present study was to assess the effect of stimulating treatment with FSH or eCG on the oocytes production in Nelore (Bos indicus) donors. The experiment was carried out at Biotec (Cesumar farm, Maringá, Paraná State, Brazil). Forty-two cows that originated from the same genetic group, between 4 and 9 years old were used, with an average weight of 420 kg. The cows received an intramuscular injection of estradiol benzoate (EB, 2 mg) and an ear implant of Norgestomet^® (3 mg). Then, they were divided in 3 groups: control group (n = 14); group 1 = eCG treatment (n = 14); and group 2 = FSH treatment (n = 14). In group 2, cows received on 120 IU of FSH on Days 5 and 6, divided in 4 doses that were administrated at 12-h intervals. On Day 7, all implants were removed and ovum pick-up (OPU) was performed. The results were statistically analyzed by Proc GLM (version 8.0, SAS Institute, Cary, NC, USA) and the mean differences were analyzed by Tukey test. Of 42 OPU sessions, a total of 627 oocytes were recovered, of which 502 were viable and 125 were degenerated, but there were no significant differences (P > 0.05) between the groups, as shown in Table 1. We conclude that the gonadotrophic stimulations with FSH or with eCG used in this study did not increase the overall quality of the viable oocytes. More research is needed to determine the optimal ovarian stimulation protocol in Nelore cows.

Table 1.  Number of oocytes recovered after OPU session in cows that were superstimulated with FSH or eCG¹