Preliminary studies on bovine embryo survival following short-term storage at 4°C

A total of 113 non-surgically collected bovine embryos, 5-8 days of age, were stored for 48 hours at 4°C in a modified phosphate-buffered saline solution (PBS). Following storage, embryos were cultured for 8-12 hours at 37°C, and those which were morphologically normal were transferred to synchronized recipients by several methods designed to achieve twin pregnancies. Embryos which were collected and transferred on the same day served as controls. Of 113 embryos stored, 47 (42%) appeared to be transferable after the brief culture period. There was a marked breed effect on viability after refrigeration, with Hereford embryos surviving significantly better than Angus embryos (71% vs. 12%, respectively, p < .001). Post-transfer embryo survival of stored and control embryos, based on actual calvings, was 34 and 48 percent, respectively, a difference which was not significant (p=0.3). A marked difference in pregnancy rate following non-surgical transfer by 2 different technicians was noted (50% vs. 21.7%, respectively).