The Effect of Different Recipient Synchronisation Protocols on Pregnancy Rates in Cryopreserved Embryo Transferred Cows

The aim of this study was to compare the effect of different oestrus synchronisation protocols on pregnancy rates in cryopreserved-thawed embryo transferred cows. For this purpose, the recipient animals’ oestruses (n=50) were synchronised with two different synchronisation protocols. In the first group (Prostaglandin F2 alpha (PG) group, n=24), two intramuscular administrations of 500 μg of cloprostenol were performed at 11-day interval. In the second group (implant group, n=14), an ear implant containing 3 mg norgestomet was inserted subcutaneously in the ear of each cow for 10 days. In addition, intramuscular form of 3 mg norgestomet+5 mg oestradiol valerate was admistrated at the same time. On d 9, 500 μg of cloprostenol (PG) was administered intramuscularly. In the third group (Control, n=12), cows exhibiting spontaneous oestrus were included in the study. After synchronisation, embryos were transferred into the uterine horn ipsilateral to the corpus luteum by epidural anesthesia on d 7 (oestrus= d 0). Pregnancy detection was performed on d 30, 60 and 90 after oestrus. Pregnancy rates were 66.6%, 64.3% and 33.3% on d 30 in groups PG, Implant and control, respectively. Embryonic losses were detected only between d 30 and 60 in PG group (n=4) and Implant group (n=2). There was no significant difference for pregnancy rates between groups. In conclusion, higher pregnancy rates were obtained in synchronised cows than in controls, and there was no significant difference between synchronisation groups.