Developmental Competence of Sheep Oocytes Collected by OPU After Different Ovarian Hyperstimulation Treatments

Our aim was to compare the developmental capacity of sheep oocytes obtained by OPU and then matured, fertilised and cultured in vitro after two different ovarian hyperstimulation treatments. Sheep were divided into three groups: a) constant FSH doses administration; b) decreasing FSH doses administration; c) no FSH treatments. Sheep were synchronised by the insertion of intravaginal sponges left in situ during 11 days; FSH (total dose: 96 I.U.) was administered in 4 doses given every 12 hours starting on day 9. Twelve hours after the last FSH administration sheep were restrained on a laparoscopic table under general anaesthesia and follicles were aspirated utilising an 18 G needle. In group a, we put in culture for the successive in vitro procedures (IVM/IVF/IVC) 86.2% of the oocytes recovered (14.5 oocytes/OPU), obtained 28.3% blastocysts. In group b, we cultured 91.3% of the oocytes recovered (17.4 oocytes/OPU), obtained 16% blastocysts. In group c, we cultured 76.2% of the oocytes recovered (10.6 oocytes/OPU), obtaining 7.3% blastocysts. These results indicate that there is a significant difference (p < 0:05) between the numbers of embryos obtained in treated versus non treated animals, while between the two ovarian hyperstimulation treatments we found no significant difference. (Supported by RAIZ).