The aspartate aminotransferase (AspAT) activity in seminal plasma indicates that the spermatozoa cell membrane damage. As a consequence of such defect, AspAT leaks from the spermatozoa to the plasma (CIERESZKO et al., 1992). A comparison of AspAT activity in seminal plasma of the boars in particular groups indicates that an addition of 0.5 mg Se + 60 mg vitamin E per 1 kg of ration prevented cellular membrane damage in spermatozoa.