Aim: In this study, it was aim to determine the rates of the effect of the lasting time from thawing-transfer until to transfer during transferring of cattle frozen embryos with ethylene glycol by direct transfer method on pregnancy rates.

Materials and Methods: Recipients (n=56) were selected from the cows whose estrus were synchronized with two times injections of 0.150 mg d-cloprostenol 14 days intervals. Embryos were transferred into recipients 7 days after the detection of recipients estrus (estrus= day 0). After embryos were threated 25 seconds within 25oC water bath to thaved then they were transferred to the recipients in minutes as follows; 0-5 (Group 0-5, n=27), 6-10 (Group 6-10, n=16) or 11-25 (Group 11-25, n=13) which all embryos were transferred into the uterine horn ipsilateral to the corpus luteum. Pregnancy diagnosis were done on day 28 used by ultrasound.

Results: Pregnancy rates were determined in 59.3%, 50% and 23.1% within G 0-5, G 6-10 and G 11-25 groups, respectively. Therefore, pregnancy rates were not statistically significant (P>0.05) between G 0-5 & G 6-10 with G 6-10 & G 11-25 while it was lower than the group of G 11-25 compared to the group of G 0-5 (P<0.05).

Conclusions: According to this study, frozen embryos by ethylene glycol should be transferred into recipients in within 10 minutes after thawing is concluded.