Abstract
In order to improve the reproductive performance during 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). Conception rate was improved in cows with ETFAI compared to conventional AI as control (n=195) (30.4% vs. 13.8%; P<0.01). However, higher fetal loss was observed in ETFAI compared to controls (38.1% vs. 7.4%; P<0.05). Four cases of twin pregnancy resulted in 2 singleton and a twins. There was no difference in plasma progesterone level on d0 or d7 (d0=AI), but rather lower body temperature was observed on d7 or d8 (38.7 C vs. 39.4 C, 38.8 C vs. 39.1 C; P<0.05) in pregnant cows compared to opens. ETFAI could improve reproductive performance in dairy cows during summer period in south western Japan.
