Vitrification of in vitro mature alpaca oocyte: Effect of ethylene glycol concentration and time of exposure in the equilibration and vitrification solutions

The effect of different ethylene glycol concentrations, times of exposure and vitrification procedure on viability, cleavage and blastocyst rate of in vitro matured alpaca oocytes chemically activated after vitrification was analyzed. In Experiment 1, oocytes were incubated for 12–15 min with different concentrations of ethylene glycol (EG) in the equilibration solution (ES) followed by chemical activation and in vitro cultured for 8 days to determine oocyte viability, cleavage and blastocyst rates. In Experiment 2, oocytes were incubated in the equilibration solution containing 4% of EG for 12–15 min and then randomly assigned to vitrification solutions containing 25, 35 or 45% of EG for 30 s, vitrified and stored at −196 °C. In Experiment 3, oocytes were incubated in the equilibration solution containing 4% of EG for 12–15 min and then randomly assigned to the vitrification solution containing 35% of EG for 15, 30 or 45 s, vitrified and stored at −196 °C.For Experiments 2 and 3, non-vitrified and vitrified oocytes were activated and cultured in vitro. In Experiment 1, oocyte viability was lowest at concentrations of 6 or 8%, intermediate at 2 or 4% and highest at 0% of EG. Oocyte viability and cleavage rate were affected by EG concentration, time of exposure in the vitrification solution or vitrification procedure in Experiment 2 and 3. Alpaca oocytes were viable after vitrification, given that oocyte viability, cleavage and blastocyst rate were affected by the vitrification procedure, EG concentration and time of exposure in the equilibration and vitrification solutions.