The purpose of this experiment is to compare the pregnancy rate (PR) according to the state of the ovaries and uterus, according to the number of embryos transferred from cows and heifers and to investigate the method of artificial twin induction with Hanwoo in vitro fertilized (IVF) embryos by embryo transfer (ET). Looking at the PR according to the condition of the ovaries and uterus, the result was not influenced by the condition of the ovaries, but was significantly influenced by the state of the uterus. The PR according to the number of embryos transferred from cows was 36.8%, 53.0%, 50.5% for 1, 2, and 3 embryos respectively, and although there was a higher frequency of twin calves with 3 embryos than with 2, the calving rate was the highest with 2 embryos. In case of heifers, the transfer of 1 embryo showed the best pregnancy and calving rate, and although the PR was similar with 2 embryos (67.7 versus 66.4), in case of 2 embryos transferred there was high frequency of embryonic loss( 6.1%) occurred when a cow was diagnosed at 28 and 53 d after ET, total loss (21.3%; sum of fetal death, abortion and stillbirth after pregnant diagnosis at 60 day).

ABSTRAC   INTRODUCTION   MATERIALS AND METHOD    In Vitro Embryo Production    Artificial Estrus Induction    Embryo Transfer    Pregnancy Diagnosis    Comparison of PR according to the State of Uterus and Ovaries    Comparison of PR according to the Number of TransferredEmbryos    Artificial Induction of Twining in Hanwoo Cows    Statistics   RESULTS AND DISCUSSION    The Effects following the States of Ovary and Uterus    Impact of the Number of Transferred Embryos    Artificial Production of Twin Calves in Hanwoo Cows   REFERENCES

• Duk-Jung Kim(Department of Animal Science, Chungbuk National University, Cheong-ju 361-763, Korea, Hankook Life Science Institute, Seoul 110-521, Korea)
• Nam-Hyung Kim(Department of Animal Science, Chungbuk National University, Cheong-ju 361-763, Korea)
• Jong-Wan Lee(Department of Animal Resources Community, KongJu National University, Kong-ju 314-701, Korea)
• Kon-Joong Kim(Department of Animal Resources Community, KongJu National University, Kong-ju 314-701, Korea)
• Gye-Woong Kim(Department of Animal Resources Community, KongJu National University, Kong-ju 314-701, Korea)
• Do-Joong Yoon(Department of Animal Science, Chungbuk National University, Cheong-ju 361-763, Korea, Department of Animal Resources Community, KongJu National University, Kong-ju 314-701, Korea) Corresponding author