• Journal of Embryo Transfer
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• v.23 no.4
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• pp.291-298
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• 2008

We separately cultured follicular oocytes collected from individual ovaries of slaughtered Korean native cows and examined both the embryonic development rate and pregnancy rate after embryo transplantation according to the meat yield and quality grades of the source beef carcass. Oocytes from meat yield grade B cows exhibited a higher fertilization rate and embryonic developmental rate to the eight-cell stage than oocytes from grade A or C animals (p<0.05), but there was no significant difference in rate of development to the blastocyst stage among meat yield grades A, Band C. The oocyte cleavage rate and development rate to the eight-cell stage from meat quality grade 3 cattle was higher than grades 1++, 1+, 1 and 2 (p<0.05). Embryos derived from grade animals displayed a development rate to the blastocyst stage of 19.4%, which was also higher than all other meat quality grades (p<0.05). Transplantation of in vitro-cultured oocytes from meat yield grade A ovaries led to a higher pregnancy rate (64.2%) than in vitro-cultured oocytes from meat yield grade B ovaries (56.5%), but there was no significant difference between the two groups in pregnancy or abortion rates. In conclusion, embryonic development rate and pregnancy rate has a close relation to meat quality grades of the source beef carcass, this results is to give information for the Korean native cows improvement of breed.

• Clinical and Experimental Reproductive Medicine
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• v.40 no.3
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• pp.122-125
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• 2013

Objective: The majority of embryo transfers (ETs) to date have been performed on day 3 to reduce the potential risk of developmental arrest of in vitro cultured embryos before ET. Development of sequential media has significantly improved culture conditions and allowed blastocyst transfer on day 5. While day 5 ET provides higher clinical pregnancy outcomes with reduced risks of multiple pregnancies, it still has potential risks of developmental arrest of IVF embryos. The aim of this study was to evaluate the clinical outcomes of day 4 ETs and compare the efficacy of day 4 ET with day 5 ET. Methods: From 2006 to 2009, a total of 747 fresh IVF-ET cycles were retrospectively analyzed (day 4, n=440 or and day 5, n=307). The cycles with any genetic factors were excluded. The rates of matured oocytes, fertilization, good embryos, and clinical pregnancy of the two groups were compared. The chi-square test and t-test were used for statistical analysis. Results: There were no significant differences between the two groups with respect to the mean age of the females and rates of matured oocytes. The pregnancy outcomes of day 4 ET (40.7%) were similar to those of day 5 ET (44.6%). The implantation rate of day 5 ET (24.2%) was significantly higher than that of day 4 ET (18.4%) (p=0.003). Conclusion: Day 4 ET can be chosen to avoid ET cancellation in day 5 ET resulting from suboptimal circumstances in the IVF laboratory, but the decremented quality of embryos for transfer and the decreased pregnancy rate must be taken into consideration.