Abstract：The purpose of this investigation was to improve the fertilization efficiency of bovine sexed sperm. In order to search an appropriate incubation time, we co-cultured bovine oocytes with sexed sperm for 8 and 22 h, respectively. Meanwhile, we compared effect of two mediums on developmental capacity of sexed zygotes, including G-1/G-2 sequential medium and SOFaa single medium. The results showed that the cleavage rates of sexed zygotes were (50.88±4.44)% and(55.9±4.52)%(P>0.05) for 8 and 22 h incubation time, respectively. Furthermore, the blastocyst rates were (41.16±5.12)% and (35.05±5.02)%(P>0.05), respectively. However, the hatched blastocyst rate of sexed zygotes in 8 h incubation time was (52.56±6.95)%, obviously higher than that of 22 h(39.81±6.38)%(P<0.05). On other hand, in terms of the cleavage rate, the blastocyst rate and the hatched blastocyst rate, we found that there were no significantly difference between G-1/G-2 sequential medium and SOFaa single medium. Whereas, compared to the SOFaa medium, the sexed blastocysts cultured in G-1/G-2 medium had a larger cell number of blastocyst(113.9±9.46 vs 102.0±9.97)(P<0.05). These results suggest that reducing oocytes and sexed sperm incubation time can improve the hatched blastocyst rate of bovine sexed zygotes. According to cell number of blastocyst, G-1/G-2 sequential medium can be more suitable for in vitro culture of bovine sexed zygotes.
