Abstract:

[Objective] This study was conducted to explore the ovum pick-up and in vitro fertilization （OPU/IVF） technology in cattle, and to establish a high-efficient in vitro embryo production system for cattle. [Method] The fresh ovaries of healthy cattle collected from slaughterhouses were used as experimental materials to perform oocyte maturation as well as fertilization and embryo culture under in vitro conditions, with focus on the effect of leptin supplementation in culture medium on blastocyst rate. Healthy Holstein dairy cows （n=10） and Wagyu cattle（n=10） aged 13 to 15 months were selected as donors, and ovum pick-up as well as oocyte maturation and embryo production under in vitro conditions were carried out. For both breeds, the number of available oocytes and blastocysts was recorded, and the cleavage rates and blastocyst rates were calculated. After thawing of the prepared frozen embryos of the donors, Holstein dairy cows were used as recipients for embryo transfering. The pregnancy rates of the recipients receiving the in vitro produced embryos of the Healthy Holstein dairy cows and Wagyu cattle were measured on day 45 after embryo transfering. [Result] Addition of 30 U/mL leptin in the culture medium significantly （P<0.05） increased the blastocyst rate of the in vitro cultured cattle embryos of slaughterhouse origin. For the donors, 7.5 and 8.1 usable oocytes were averagely obtained per Holstein dairy cow and per Wagyu cattle, respectively. The cleavage rates of Holstein dairy cow and Wagyu cattle were 84.00% and 82.71%, respectively, and there was no significant （P>0.05） difference between them. Under the in vitro conditions, 4.3 and 3.7 available blastocysts were averagely obtained per Holstein dairy cow and per Wagyu cattle, respectively, and the blastocyst rate of Holstein dairy cow （57.33%） was significantly （P<0.05） higher than that of Wagyu cattle （45.68%）. The pregnancy rates of Holstein dairy cow embryo group and Wagyu cattle embryo group were 54.17% and 55.79%, respectively, and no significant （P>0.05） difference was observed. [Conclusion] The established OPU/IVF system effectively improves the utilization efficiency of high-quality female cattle, reduces its production costs, and provides references for the optimization of in vitro embryo production system for cattle.

Key words: Holstein dairy cow, Wagyu cattle, OPU/IVF, in vitro embryo production