Semen characteristics in Acipenser persicus in relation to sequential stripping

Seminal plasma indices (osmolality and ionic composition), spermatozoa concentrations and sperm motility were studied in the Persian sturgeon, Acipenser persicus in order to use these semen biomarkers to measure performance in terms of sequential stripping effects. Semen samples were collected by hand stripping from nine induced males injected intramuscularly with sturgeon pituitary homogenized extract at dosages of 50-70 mg Kg(-1) body weight, 24h after spawning induction (first stripping), 12h after first stripping (second stripping) and 12h after second stripping (third stripping). The spermatozoa concentration and osmolality of the seminal plasma decreased significantly with subsequent stripping. The Na+, K+ and Cl- ions concentrations were predominate in the seminal plasma at different stripping times. But, there were no significant differences between ions concentrations at different stripping frequencies (P > 0.05). The percentage of motile spermatozoa (after 15-30 sec post-activation) and total of period of sperm motility decreased significantly (P < 0.05) when the stripping frequency increased, where the semen diluted in fresh water (control). Interestingly, the observed effects of stripping times on the sperm motility could overlap by manipulating of sperm activation medium. The results showed that sperm motility parameters significantly were increased in terms of percentage of motile spermatozoa and total periods of sperm motility compared to control (fresh water) after discharge of sperm into a solution with osmolality 50mOsmol Kg(-1) at second and third strippings. Probably, the sequential stripping influences on sperm motility via enzymatic activities. Nevertheless, further studies are needed to understand the physiological relationships.