The study aims to assess the embryo development and survivability of bovine embryos cultured in vitro by addition of cysteine. The rates of metaphase II formation are not significantly different among the three groups(73.8% for TCM199, 76.9% for TCM199 with 0.3mM cysteine and 83.8% for TCM199 with 0.5mM cysteine). No differences on cleavage rate(70.6~74.6%) was observed among three culture medium(70.6% for TCM199, 71.3% for CR1aa, and 74.6% for SOF) with 0.5mM cysteine. However, significantly(P<0.05) higher development rate was obtained in the blastocyst stage by adding 0.5mM cysteine in SOF medium(35.6%) than in TCM199(27.6%) or CR1aa(26.6%). No significant differences in the cleavage rates were observed among the three culture. After freezing the blastocysts cultured with 0.5M cysteine, the re-expansion rates ranged from 61.3% to 86.4% among groups, and hatching rates are from 26.3% to 46.9% among groups. The rates of re-expansion and hatching are significantly(P<0.05) higher in SOF medium(86.4% and 46.9%, respectively) than those in TCM199(61.3% and 26.3%) and CR1aa medium(87.1 and 44.4%). After thawing, the blastocyst re-expansion rate become significantly(P<0.05) higher in in vivo (87.1%) and in vitro (70.3%) embryos. In conclusion, our results demonstrate that supplementation of IVM and IVC media with 0.5mM cysteine improved the quality of in vitro production of embryo and post-thawed embryo. Future studies comparing these culture systems in well-designed trials should be performed.

The recovery of epididymal sperm in animals is considered as one of the important tools to preserve high value or endangered species. However, there are no appropriate castrating indicators such as months of age in bull, sperm morphology, and motility, particularly in young Korean native bull (Hanwoo). Therefore, this study aimed to investigate sperm number, morphology, and motility of sperm in the epididymis tail of young Hanwoo bulls at 8 and 15 months of age. After castration, epididymal tails were collected and minced with blades to recover sperm. In experiments 1 and 2, sperm number, morphology, and motility were examined. Total number of sperm and percentage of normal sperm from bulls at 8 months of age was lower than that of bulls at 15 months of age after collection (P<0.05). Percentage of abnormal head, tail, proximal cytoplasmic droplet, dead and damaged acrosome of sperm from bulls at 8 months of age were higher than those of bulls at 15 months of age (P<0.05). In experiment 3, sperm motility from bulls at 8 and 15 months of age were examined before freezing and after thawing. Frozen-thawed sperm at 8 months of age showed low total motility and motile sperm with ≥ 25 μm/sec compared to those at 15 months of age and commercially-used sperm (P<0.05). In conclusion, sperm derived from the epididymal tail of bulls at 8 months of age showed high abnormal morphology and poor motility, which are not adequate for AI and IVF. On the other hand, sperm derived from the epididymal tail of bulls at 15 months of age showed high normal morphology and motility.