Cryopreservation of Embryo by Concentration of Ethylene Glycol and Day 6, 7, 8, 9 Embryo in Korean Native Cattle (Hanwoo)

This study was carried out to effects of ethylene glycol concentration, sucrose and culture day of in vitro production embryo on slow-down freezing in Hanwoo. 6, 7, 8 and 9 day embryos produced in vitro were frozen using 1.8M EG+0.1M sucrose, 1.8M EG+0.5% BSA and 1.5M EG+0.1M sucrose media. Survivability was confirmed after frozen-thawed 24 and 48h and ICM, TE cell number were counted by Hoechst 33342 and PI staining after frozen-thawed 24h. As a result, 1.8M EG+0.1M sucrose group was most significantly (p<0.05) higher compared with the other treatment groups on survivability, TE and total cell number after frozen-thawed 24h ($94.2{\pm}2.6%$, $94.67{\pm}3.4$ and $129.67{\pm}5.5$). ICM number did not found significant (p<0.05) differences between the three treatment groups. in 6, 7, 8 and 9 day of embryos using three types of freezing media, frozen-thawed, 1.8M EG+0.1M sucrose groups with embryos cultured 8 day was significantly (p<0.05) highest survivability to $98.3{\pm}1.7%$ after frozen-thawed 24h. 1.5M EG+0.1 sucrose group with embryos cultured 9 day was significantly higher survivability than group of embryos cultured 8 day after frozen-thawed 24 and 48h. In conclusion, 1.8M EG+0.1M sucrose media is considered to be effective to cryopreservation of embryos cultured 8 and 9 day.