Seminal plasma composition and its relationship with physical spermatological parameters of Grass carp ( Ctenopharyngodon idella ) semen: with emphasis on sperm motility

In this research, the mineral and organic composition of the seminal plasma, physical spermatological parameters and their physiological relationships were investigated in grass carp ( Ctenopharyngodon idella ). The seminal plasma contained 98.14±5.23 mM L −1 (Na + ), 380.85±25.95 mM L −1 (K + ), 30.25±4.96 mg dL −1 (Ca 2+ ), 19.16±1.70 mEq L −1 (Mg 2+ ), 1.36±0.11 mg dL −1 glucose, 0.37±0.08 g dL −1 total protein, 12.02±1.18 mg dL −1 cholesterol, 14.85±1.50 mg dL −1 triglyceride and 43.5±9.56 mg dL −1 urea. The following spermatological parameters were found: sperm volume 14.44±1.16 mL, sperm motility 80.60±1.55%, movement duration 67.68±4.32 s, density 15.43±0.72 × 10 9  mL −1 , total density 337.43+45.86 × 10 9 and pH 7.24±0.17. The Na + and Ca 2+ ions correlated negatively with spermatozoa motility ( r =−0.453, P >0.05 and r =−0.192, P >0.05) respectively. The K + ion correlated positively with spermatozoa motility ( r =0.545, P >0.05). But a statistically significant correlation was not observed between sperm motility and seminal plasma parameters. The following correlations were observed between mineral and organic components. The Mg 2+ was positively correlated with glucose and cholesterol ( r =0.692, P <0.05 and r =0.680, P <0.05) respectively. A highly significant positive relationship was also found between Mg 2+ and total protein ( r =0.837, P <0.01). On the other hand, a significantly negative relationship was found between Ca 2+ and triglyceride ( r =−0.639, P <0.05). These parameters should be considered when developing procedures for either artificial fertilization or for cryopreservation of grass carp sperm.