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).