Evaluation of cellulose acetate/nitrate filters for the study of stallion sperm motility.

Stallion semen was diluted in a Hepes-supplemented buffer (CM) (10(6) spermatozoa/ml) and placed in the upper well of a Sykes-Moore chemotaxis chamber. Chambers were incubated in a humidified atmosphere (5% CO2 in air) at 37 degrees C for 1 and 2 h and spermatozoa were allowed to swim through filters with a mean pore size of 3,5 or 8 micron. Spermatozoa entered filters of all three pore sizes. Distance travelled was greater for each increase in pore size (P less than 0.01) but did not differ (P greater than 0.05) between 1 and 2h of incubation. Extended semen from stallions of different fertility was analysed for the minimal concentration of spermatozoa needed to enter filters with a 3 micron pore size. Sperm progression into the filter reflected the motility of the ejaculate. Assuming that sperm motility is a good indicator of fertility, this method may be useful for estimating the fertility of a stallion. Progression of spermatozoa into filters with a pore size of 3 micron was hampered by supernatants from overnight cultures of Streptococcus zooepidemicus and Enterobacter aerogenes. Motility decreased after 2h of incubation in supernatant from S. zooepidemicus diluted 1:5 and E. aerogenes supernatant diluted 1:5 and 1:10 in culture medium. In contrast, the bacterial supernatants were chemokinetic to horse neutrophils and did not affect their viability.