Filtration of bovine semen. II. Factors affecting the recovery rate of spermatozoa

Abstract

Filter and semen related factors were studied to improve the post-filtration recovery rate of bovine spermatozoa using a Sephadex (0.6 g) ion-exchange (diethylaminoethane (DEAE) and carboxy-methyl (CM) celluloses, 0.25 g each) column. Mixing together the components of the column did not improve the recovery rate of spermatozoa compared with layering ( P>0.05). A second post-filtration washing of the column with clean buffer improved the recovery rate by 8–9%, but the quality of spermatozoa was lower than after a first wash ( P<0.01). Higher rates of filtration did not increase the number of spermatozoa recovered in the filtrates ( P>0.05). The recovery rates of spermatozoa were 2.4%, 68.3% and 70.5% at 4°C, 22°C and 37°C ( P<0.01) respectively. The quality of filtrate was significantly less at 37°C than at 22°C in terms of visual motility ( P<0.025), progressive motility ( P<0.0005), progressive velocity ( P<0.025), linear index ( P<0.0005), and percentages of live cells ( P<0.0005) and normal acrosomes ( P<0.025). Motility of spermatozoa seemed to be essential for successful filtration. An inverse relationship was found between the recovery rate and the quality of the semen or spermatozoa. It was concluded that a single wash of the column with extended semen at 22°C with a flow rate of 1.5 ml min −1 yielded the best semen quality with an optimum recovery rate of spermatozoa.