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 t he increase in sperm volume in response to hypo-osmotic stress. In this stu dy the volumetric method was applied to bull ejaculates, and the relationsh ips of volumetric parameters, osmolality of seminal plasma, and concentrati on 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 relativ e volume shift of the mean volume correlated significantly with motility be fore and after thawing (P < 0.05). NRR correlated significantly with iso-os motic cell volume (-0.49; P < 0.05) and with the relative volume shift (0.5 1, P < 0.05). The prediction level of regression models was improved when v olumetric parameters (iso-osmotic cell volume) were included in the multipl e regression model. Therefore, using electronic volume measurement as a com ponent for fast, correct and valid (up to 50000 cells), recording sperm-cel l population may help to evaluate ejaculate quality more precisely.