This study was conducted to investigate optimal time of artificial insemination (AI) to Hanwoo female after natural estrus. AI was occurred 12 and 24 hours after natural estrus in both heifer and multiparous recipient then pregnancy and parturition rates were estimated. Results indicated that AI performed at 24 hours after natural estrus showed significant (p<0.05) higher pregnancy rate in both heifer and multiparous recipient groups with significantly (p<0.05) higher abortion rate. However, there are no significant differences of parturition rate, twin birth and sex ratio in both heifer and multiparous recipient groups. Therefore, our results may suggest that performance of AI at 24 hours after natural estrus promise higher pregnancy rate than AI at 12 hours after natural estrus in both heifer and multiparous recipient.

ABSTRACT   INTRODUCTION   MATERIALS AND METHODS    Artificial Insemination and Recipients    Pregnant Confirmation    Statistic Analysis   RESULTS AND DISCUSSION   REFERENCES

• Jung Seok Yang(Department of Animal Science and Biotechnology, Sangji Youngseo College)
• Young-Tae Heo(Department of Animal Sciences, Chungbuk National University)
• Sang Jun Uhm(Department of Animal Science and Biotechnology, Sangji Youngseo College) Corresponding author
• Dae Hwan Ko(Department of Animal Science and Biotechnology, Sangji Youngseo College) Corresponding author