Effects of donor sex and different cell treatments on development of yak–bovine interspecies nuclear transfer embryos

The purpose of this study was to evaluate the effects of donor sex, cell cycle synchromization treatments and donor nuclei obtained from fresh or frozen-thawed on in vitro developmental competence of yak-bovine interspecies nuclear transfer (NT) embryos. Bovine (Bos taurus) oocytes were used as recipients, and yak (Bos grummiens) ear fibroblast cell as donors. Results indicated that the development rate of male blastocysts was higher than that of female (56.6% vs 39.5%, P﹤0.05), whereas cleavage and total cell number had no difference between the two groups; No significant difference was observed in the blastocysts development and quality of donor treated with serum starvation or confluence inhibition; And there was no significant difference in embryos development of use fresh or frozen-thaw donor cell, whereas cleavage in group of fresh donor cell was significantly higher than that of frozen-thaw group (54.5% vs 78.2%, P﹤0.05). The results demonstrated that donor sex could impact the in vitro developmental competence of yak-bovine interspecies NT embryos, whereas different cell cycle synchromization treatments and freeze had little influence on it.