Effect of Embryo Transfer following Artificial Insemination (ETFAI) on Reproductive Performance in Dairy Cows in South-Western Japan

In order to improve the reproductive performance during the summer period, embryo transfer (ET; Japanese black embryo) following artificial insemination (AI; Holstein semen: ETFAI) was conducted in dairy cows in south-western Japan (n=56). The conception rate was improved in cows with ETFAI compared with conventional AI, which served as the control (n=195; 30.4% vs. 13.8%, P<0.01). However, higher fetal loss was observed in ETFAI compared with the controls (38.1% vs. 7.4%, P<0.05). Four cases of twin pregnancy resulted in 2 singletons and a set of twins. There was no difference in the plasma progesterone level on d0 or d7 (d0=AI), but rather lower rectal temperature was observed on d7 or d8 (38.7°C vs. 39.4°C and 38.8°C vs. 39.1 °C, P<0.05) in pregnant cows compared with those that were open. ETFAI could improve reproductive performance in dairy cows during the summer period in south-western Japan.