The Influence of Centrifugal Parameters on the Performance of Early-delipated Pig Oocytes

Purpose High fat content in oocytes is the main factor that affects porcine oocyte and embryo freezing effect, the method of centrifuging delipation can improve the freezing success rate. In this study, we removed the fat from the porcine oocytes with different centrifugal parameters, and screened out an optimal centrifugal parameter through investigating the effect of early delipation on oocytes, in vitro and in vivo embryo development and freezing.

Method We set various centrifugal parameters to perform the early delipation of porcine oocytes, established the reconstructed embryos using somatic cell nuclear transfer, and analyzed in vitro and in vivo developmental effect of the reconstructed embryos before and after vitrification by separating the fat layer of porcine oocytes, calculating the cleavage rate and blastocyst rate of reconstructed embryos, the survival rate of frozen-thawed embryos and the pregnancy rate of surrogate sows.

Result When the centrifugal speed × the centrifugal time was 10 000 r/min × 20 min, the early-delipated effect was the best. Under such centrifugal parameter, the cleavage rate and blastocyst rate of early-delipated reconstructed embryos were 65.38% and 13.46%, respectively; the survival rate and blastocyst rate of frozen-thawed 2-4 cells, 5-8 cells and 9-16 cells were 49.09% and 12.72%, 52.75% and 2.20%, and 78.57% and 21.42%, respectively; the surrogate sows transferred the frozen embryos were successfully pregnant.

Conclusion This study suggests that the porcine oocytes after early-delipation can be directly used for cryopreservation of embryos and the optimum centrifugation parameter is 10 000 r/min×20 min.