EFFECT OF FILTRATION ON POSTTHAW QUALITY OF BULL SEMEN

Semen from 4 Holstein bulls was diluted in 4 different extenders, filt ered with Sephadex ion-exchange column, and frozen in liquid nitrogen. Sperm motility, progressive motility, path velocity, progressive velo city and the percentage of normal acrosomes of filtered and nonfiltere d semen were recorded before and after freezing. Semen characteristics were significantly influenced by extender, filtration and freezing. B efore and after freezing, motility measurements and the percentage of normal acrosomes were higher (P<0.001) in filtered than in nonfiltered spermatozoa. Post-thaw recovery rate of:motile spermatozoa was higher in filtered semen than nonfiltered (68 vs 39%, P<0.0001). The reducti on in motility, progressive motility and the percentage of normal acro somes during freezing and thawing processes were significantly lower ( P<0.0001) in filtered semen (34, 34 and 4%, respectively) than nonfilt ered (59, 54 and 15%, respectively). Post-thaw viability of spermatozo a was significantly affected by extender, filtration and time (P<0.000 1). Immediate (0 h) post-thaw motility of nonfiltered semen (29%) was similar to 4-h post-thaw motility of filtered semen (25%; P>0.05). In conclusion, bull spermatozoa recovered by Sephadex ion-exchange filtra tion showed better post-thaw viability.