The effects of trehalose and sucrose on frozen spermatozoa of Yunnan semi-fine wool sheep during a non-mating season.

To improve the quality of frozen spermatozoa of Yunnan semi-fine wool sheep, the protective effect of trehalose and sucrose on frozen ram spermatozoa during a non-mating season was evaluated and compared in this study. Briefly, following collection by electric stimulation, equilibration at degree C following dilution with the freezing extender, and pre-freezing in liquid nitrogen vapor, the ram spermatozoa were frozen in liquid nitrogen. After thawing, viability, motility, acrosome status, membrane integrity, and phosphatidylserine (PS) distribution was determined using a computer-assisted spermatozoa analysis system and flow cytometry. The data indicated disaccharide can improve the quality of frozen ram spermatozoa. With a trehalose concentration of 100mM, the post-thaw viability and motility (80.56 +/- 6.89% and 46.07 +/- 5.84 %) of ram spermatozoa were significantly more than those of ram spermatozoa frozen with no disaccharide (65.46 +/- 18.96 % and 34.62 +/- 9.32%, P<0.05). However, the effect of sucrose on the viability, motility, and moving velocity of ram spermatozoa was similar to that of the control group (p > 0.05). Compared with sucrose, trehalose can significantly increase the motility of frozen ram spermatozoa (p<0.05). In addition, addition of trehalose or sucrose can efficiently protect the acrosome of frozen spermatozoa. Moreover, when the concentration of trehalose or sucrose was 100mM, the protective effect of trehalose or sucrose on the membrane integrity and PS distribution was significantly higher than that of the control group (p>0.05). However, the protective effect of trehalose on viability, moving velocity, acrosome status, membrane integrity, and PS distribution of frozen ram spermatozoa was similar to that of sucrose (p>0.05). In conclusion, the protective effect of trehalose on frozen sheep spermatozoa is superior to that of sucrose. Addition of 100mM of trehalose in the freezing extenders can improve the post-thaw quality of ram spermatozoa with respect to viability, motility, and linear velocity. Moreover, presence of disaccharide can protect acrosome and membrane of frozen sheep spermatozoa.