Differences in Hormone Levels Around Parturition in Hanwoo (Bos Taurus Coreanae) Following Artificial Insemination and Embryo Transfer

Abstract Hanwoo (Bos taurus coreanae) are well adapted to the environment of Korea and exhibit unique genetic traits; however, the perinatal mortality rate of Hanwoo is 2–3%, which imposes an economic burden. The timing of parturition is often predicted subjectively due to insufficient data on hormonal changes around parturition, and few studies have examined hormones in Hanwoo. Therefore, we measured the changes in various hormones around parturition in Hanwoo to seek an objective predictor of parturition time. We measured progesterone, prolactin, and cortisol concentrations daily in jugular vein blood samples beginning 6 days before parturition until 7 days after parturition in 14 female Hanwoo. Five were induced to conceive with artificial insemination and nine were induced to conceive via embryo transfer. Progesterone concentration decreased significantly during parturition in the embryo transfer (n = 9) and total (n = 14) groups, but did not change significantly in the artificial insemination (n = 5) ​​group. Prolactin concentration increased on the day of parturition, but did not differ significantly among the groups. Cortisol remained constant throughout. We concluded that the parturition time can be predicted in Hanwoo using progesterone concentration. This knowledge can reduce perinatal mortality, which will help to improve farm income and animal welfare.