This study was carried out to examine the efficiency of biopsy methods, and the pregnancy rate, calving and abortion rates, gestation length and birth weight of Hanwoo calves following transfer of fresh, frozen and sexed Hanwoo embryos produced in vitro. The survivability of biopsied embryos was 80.0 and 90.0% using aspiration and punching methods at 24 h after culturing, respectively. The ratios of male and female embryos were 42.1 and 52.6%, respectively, and the percentage of sex unidentified was 5.3%. Pregnancy rates was not significantly different between hCG and control group (46.4 vs. 38.5%), fresh and frozen embryos (41.3 vs. 35.0%), and sexed and IVP embryos (27.5 vs. 41.2%) (p>0.05). Calving and abortion rates of IVP and sexed embryos were not significantly different in calving (85.0 vs. 87.0%) and in abortion (15.2 vs. 13.3%) (p<0.05). Gestation length of IVP and sexed calves were 281.3 and 288.2 days in female and 283.0 and 282.3 days in male, and the birth weight of IVP and sexed calves were 23.6 and 25.0 kg in female and 24.6 and 23.8 kg in male, respectively. There were no difference in gestation length and birth weight between IVP embryos and sexed embryos (p>0.05). Administration of hCG to recipients did not improve the pregnancy rate following transfer of Hanwoo embryos produced in vitro and sexed embryos. Although the production of calves derived from sexed Hanweoo embryos cultured in vitro can be obtained, the efficiency of sexed calves production need to be improved in biopsy methods and pregnancy rate. Further study should be focused on the improvement of pregnancy rates for commercial application of embryo transfer.

Keywords: embryo sexing, biopsy, PCR, embryo transfer