Abstract:

This study aimed to investigate the effect of cyanidin-3-rutinoside added to the diluent on the cryopreservation of dairy sheep semen and to explore its mechanism of action. Fresh semen was collected from 6 East Friensian rams aged 2.5 to 3 years old and in good physical condition. After undergoing microscopic examination, the semen was mixed and divided into 6 groups. One group served as the pre-freezing group, which was diluted with a diluent without C3R. The remaining 5 groups were diluted and cryopreserved using diluents containing varying concentrations of C3R (0, 20, 40, 60, and 80 μg·mL^-1). Each group consisted of 3 replicates. The effect of C3R on the cryopreservation of dairy sheep semen was studied by evaluating related indicators of sperm quality, antioxidant capacity, and adenosine metabolism after thawing. The results indicated that the addition of C3R significantly improved sperm quality. The treatment group receiving 40 μg·mL^-1 of C3R exhibited the highest proportion of sperm forward movement and acrosome integrity, both of which were significantly higher than those in the control group (P < 0.05); The plasma membrane integrity rate in the 60 μg·mL^-1 C3R treatment group was the highest among all groups and was significantly higher than that of the control group (P < 0.05). The addition of C3R significantly enhanced the antioxidant capacity of sperm. The superoxide dismutase activity of sperm in the 40 μg·mL^-1 C3R treatment group was significantly higher than that in the other groups (P < 0.05), while the malondialdehyde content was significantly lower than that in the other groups. (P < 0.05); The total antioxidant capacity and catalase activity in the 60 μg·mL^-1 C3R treatment group were significantly higher than those in the other groups (P < 0.05); The active oxygen content in the 20 and 40 μg·mL^-1 treatment groups was significantly lower than that in the control group (P < 0.05). Therefore, under the conditions of this experiment, 40 μg·mL^-1 C3R demonstrated the best protective effect on dairy sheep sperm. Regarding adenosine metabolism, the activity of adenosine deaminase in the frozen group was significantly higher than that in the pre-frozen group (P < 0.05). Furthermore, the addition of 40 μg·mL^-1 C3R significantly inhibited the activity of adenosine deaminase and reduced the contents of adenosine and inosine (P < 0.05). Therefore, incorporating C3R into the freezing diluent can enhance the preservation efficacy of frozen semen from dairy sheep. When C3R is added at a concentration of 40 μg·mL^-1, it significantly boosts the antioxidant capacity of the sperm and decreases adenosine deaminase activity, thereby improving the quality of frozen semen from dairy sheep.

Key words: dairy sheep, semen, cryopreservation, C3R, antioxidant, adenosine deaminase