2.5. Pregnancy diagnosis
Pregnancy diagnosis was performed by ultrasound examination (Aloka Ultrasound Diagnostic Equipment, Model SSD-500; Tokyo, Japan) 30 days after TAI (Day 30) in experiment 1 and 23 days after TET (Day 30) in experiment 2. The 30-day pregnancy rate was calculated as the number of detected pregnancies divided by the total of animals submitted to TAI or TET procedure.