Comparision of different cryoprotectants on slow freezing of in vivo derived Saanen goats embryos

This study aimed to determine the effects of different cryoprotectants on the viability of Saanen goats embryos which were frozen and thawed with slow freezing method. The study was conducted on 15 Saanen goats and 3 bucks. Fluorogeston acetate (20 mg) impregnated intravaginal sponges were inserted in goats for 12 days regardless of the sexual cycle. Starting on the 9th day of intravaginal sponge administration, follicle stimulating hormone (FSH) was injected intramuscularly, every 12 hours at decreasing doses (50-50; 30-30; 20-20 mg) for 3 days. Goats were mated naturally 24 hours after removal of the sponges. Embryos were recovered by laparotomic uterine flushing on the 7th day after the first mating. Collected embryos were frozen by using 3 different cryoprotectants [ethylene glycol (EG), glycerol, and dimetil sulfoksit DMSO)] with slow freezing technique. Thawed embryos were incubated at 38.5 ºC and 5% CO2. The viability of embryos was evaluated at the 24th, the 48th, the 72nd hours after thawing. Superovulation response (≥4 Cl), embryo recovery rate and transferable embryo rate were found to be 93.3%, 72.3% and 58%, respectively. Viability rates of frozen and thawed embryos at the 24th, the 48th, the 72nd hours were found respectively to be 64.86%; 56.76%; 54.05% in EG group, 54.55%, 45.45%; 36.36% in glycerol group and 46.88%; 40.63%; 28.13% in DMSO group. Viability rates of the frozen embryos with EG were statistically better than embryos frozen with glycerol and DMSO (P<0.05) at 72nd hour. Survival rates of blastocysts frozen were 76%; 64%; 60%; 54.6% in EG group 45.5%; 36.4% in glycerol group, and 42.1%; 36.8%; 21.1% in DMSO group and at 72nd hour the difference between EG and DMSO group was significant (P<0.05). In conclusion, viability of embryos at the 24th, the 48th, the 72nd hours after thawing in EG group was significantly higher than the embryos frozen with other cryoprotectants.