The objective of this study was to investigate the result of in vivo embryo collection and pregnancy rate after embryo transfer using sex-sorted sperm of Korean brindle cattle. Donor Korean brindle cattle superovulation treated by decreasing dose of FSH injection. Embryos were recovered on 7 days after the third artificial insemination. Control group semen straw used artificial insemination contained 20 million sperm. Sex-sorted semen straws contained 4 million sperm or 10 million sperm. As for the result of the recovery of the in vivo embryos derived from sex-sorted sperm, the number of transferable embryos was significantly highly recovered to be 6.20±2.28/donor from the control group and was significantly lowly recovered to be 1.57±1.72/donor from the group treated at a sperm concentration of 10×106 (p<0.05). The number of unfertilized embryo was 0.8±1.30/donor in control group which was significantly lower than the group treated at a sperm concentration of 4×106 (p<0.05). However, there was no significant difference in the number of undeveloped ova between control and treatment groups. Pregnancy rate after embryo transfer was shown to be 35.00% in control group and 12.50% in treatment group. The karyotype analysis of the calf derived from sex-sorted sperm resulted in a similar chromosomal distribution pattern (2n=60, XX) compared to those of common Korean native cattle.

Sexed semen is commonly used for the production of calves of the desired gender. Gender selection is important in animal production industries. For example, female cattle are required for the dairy industry while males are preferred in the beef cattle industry. The present study was to assess the in vivo embryo production efficiency using the semen separated according to sex during superovulation in Hanwoo. Seventy Hanwoo donor cows were flushed on day 7 of estrus cycle with same FSH and artificial insemination by the same technicians. Embryos were recovered on 7 days after the third insemination by flushing the uterus with embryo collection medium. KPN semen straws used artificial insemination contained 20 million sperm (total number 60 million per donor). Sex-sorted semen straws contained 4 million sperm (total number 12 million per donor). The results obtained were as follows: No differences were observed in the efficiency of superovulation rates on KPN semen 87%, and sexed semen 100%, respectively. The mean numbers of total embryos are each 12.58±8.31 and 13.25±7.86. The mean numbers of transferable embryos, sexed semen were significantly lower than KPN semen (3.75±1.98 vs. 8.23±6.07, P＜0.05). The rates of unfertilized embryos from superovulation using sexed semen were significantly higher than KPN semen (50% vs. 15%, P＜0.05). The rate of degenerated 2-cell embryos from sexed and KPN semen was 60.87% and 11.11%, respectively (p＜0.05). In conclusion, these results indicate that superovulation using sexed semen was useful, but efficient embryo production was important to reducing the damage caused by the Flowcytometer-based sperm sorting procedure.

This study was conducted for SNPs in the 5'-regions of estrogen receptor-α(ESR-α), and association with calving interval (CI), service per conception (SPC) and 305 days milk yield in Hanwoo and Holstein dairy cattle. The genet-ic improvement was incurred low reproduction performance. The objective of this study was to investigate connec-tions between single nucleotide polymorphisms (SNP) of Estrogen receptor-α (ESR-α) with reproduction performance (calving interval, service per conception, and 305 d milk yield) in Hanwoo and Holstein dairy cattle. Hanwoo and Holstein blood samples were collected from 183 and 124 dam of breeding farms and DNA was extracted. Primer design was based on NCBI GenBank (Accession No. AY340579). The PCR-RFLP method with Bgl I was used to ge-notype the cattle. The result showed two variants of the ESR-α gene. The Bgl I cut the 492 bp amplification pro- duct into 322 bp and 170 bp fragments for allele G, while allele A remained uncut, resulting in two restriction frag-ments for homozygote G/G and three fragments for heterozygote A/G. We found two of different genotypes in the-se breeds, A/G and G/G. In Hanwoo, the A/G genotype frequency was 0.13, and G/G was 0.87. The CI of A/G was 382.18±10.03 days, and G/G was 381.69±5.22 days. The SPC of A/G was 1.62±0.16, and G/G was 1.32±0.04. While CI showed no significance difference, SPC exhibited significant difference (p<0.05). In Holstein cattle, the frequency of genotype A/G was 0.02 and G/G was 0.98. The 305 days milk yield of A/G was 7,253.00±936.00 kg and of G/G was 8,747.51±204.88 kg, showing no significant difference.