Sperm-cell volumetric measurements as parameters in bull semen function evaluation: correlation with nonreturn rate

Sperm-cell volume, measured electronically by cell counter, is a parameter providing information about the state and integrity of the plasma membrane by determining cell osmotic reactivity (swelling level). Electronic volume measurement is a modification of the hypo-osmotic swelling test, based on the increase in sperm volume in response to hypo-osmotic stress. In this study the volumetric method was applied to bull ejaculates, and the relationships of volumetric parameters, osmolality of seminal plasma, and concentration of sodium and potassium ions in seminal plasma, with the nonreturn rate (NRR) were examined. Significant correlations were found between volumetric parameters, conventional spermatological parameters, and NRR. The relative volume shift of the mean volume correlated significantly with motility before and after thawing (P < 0.05). NRR correlated significantly with iso-osmotic cell volume (- 0.49; P < 0.05) and with the relative volume shift (0.51, P < 0.05). The prediction level of regression models was improved when volumetric parameters (iso-osmotic cell volume) were included in the multiple regression model. Therefore, using electronic volume measurement as a component for fast, correct and valid (up to 50,000 cells), recording sperm-cell population may help to evaluate ejaculate quality more precisely.