Cryopreservation of local black rabbit spermatozoa in the Mekong delta region of Vietnam: Evaluating cryoprotectant effectiveness.

Abstract

Rabbit production is well developed in the Mekong Delta and Vietnam, with increased consumption of rabbit meat in both urban and rural areas. Consequently, meat rabbit breeds have become popular in almost all provinces in Vietnam, resulting in a decline in the population of Local Black rabbits over the years. To support breeding programs, there is a crucial need to develop a cryopreservation method. The objective of this study was to develop sperm cryopreservation protocols and determine the optimal cryoprotectant for Local Black rabbit spermatozoa. Rabbit spermatozoa were obtained and diluted with TCG-EggYolk freezing medium containing 5%, 8%, and 10% glycerol or DMSO in a 1:1 ratio. Glycerol and DMSO-free mediums served as the controls. Samples were put into 0.5-mL straws, cooled to 15°C and 5°C, then placed on nitrogen vapour for 15 min and directly immersed in liquid nitrogen at -196°C. Samples were thawed at 37°C for 60 s after being frozen for 72 h Sperm quality measures, such as viability, motility, and membrane integrity, were assessed both before and after freezing. The results showed that the average viability, average motility, and average membrane integrity were 61.9%, 53.9%, and 42.9%, respectively, after thawing with 5% glycerol, which was higher than the two higher concentrations of glycerol (8% and 10%) (p < .05). Similarly, with 8% DMSO, the average viability, average motility, and membrane integrity were 59.2%, 51.0%, and 41.8%, respectively, which were higher than the two concentrations of DMSO (5% and 10%) (p < 0.05). Therefore, the cryopreservation of local black rabbit sperm with 5% glycerol or DMSO 8% resulted in high sperm quality, but considering the practical aspect of minimizing the volume of the preservative, a concentration of 5% glycerol may be the best option.