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In the experiment I for maas production of bovine early embryos, 18~20hpi fertilized eggs (756 eggs) and parthenogenic eggs (618 eggs) which were treated by 10% ethanol were cultured in both TGM and CZB. In the experiment II, suppiment effects each in CZB and CRlaa were tested by matured and fertilized oocytes which were after 18~20hpi. In the case of experiment I after 48hr, the cleavage rates of normally fertilized eggs were 66.6% in TCM treatment and 77.7% in CZB treatment, and after 240h the blastocysts were 7.5% in TCM and 14.1% in CZB. In the parthenogenic eggs, the deavage rates at 48hr were 39.6% in TCM and 57.5% in CZB, and at 240h, the blastocysts were 0.9% in TCM and 4.4% in CZB. These results showed that the effects of CZB on developmental ability to parthenogenic eggs as well as nomally fertilized eggs are relatively high. In experiment W, the effect of exposing the cleaved embryos to CZB for 30h on the blastocyst formation was examined. Similar rates of blastocyst formation were obtained both in TCM and CZB, suggesting that CZB exposure. during ealry development is critical. In experiments III ~ V, the effects of supplements were examined. The cleavage rates of CZB treatments at 48h were 83.8% in control, 78.1% in BSA+A.A+SIT, 75% in 5% FCS+A. A+SIT, 88.6% in BSA+A.A+SIT and not co-cultured BSA+A.A+SIT had 85.7% and in the case of 240h blastocysts showed 22.6, 0.0, fl.1, 6.5 and 0%, respectively. As a result, this study showed that CZB was effective culture system for in vitro development, and that CZB and CR₁aa had no significant differences and effects between them. It may be concluded that in the simple media containing supplements could replace the co-culture systems of bovine early embryo development.
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