Effects of differing gentamicin concentrations in semen extender on spermatozoa motility and velocity in fresh and cooled stallion semen

Ten light-horse stallions (ages 5-16) were used to determine the effects of differing concentrations of gentamicin Sulfate in semen extender on sperm Motility and velocity in both fresh and cooled stallion semen. Semen was collected once from all stallions from October 1997 through March 1998. Immediately after collection, semen was extended with a dried-Skim Milk based extender (pH = 7.0) Containing either 0, 500 or 2000, mug/ml gentamicin sulfate to a final concentration of 10 X 10(6) spermatoza/ml. Average path velocity decreased ( p < .01) in cooled semen (44.2 +/-2.3 mum/sec) when compared with fresh semen (65.1 +/-2.2 mu /sec). However, there was no difference in average path velocity (VAP) between Samples extended with either 0, 500 or 2000 mug/ml of gentamicin sulfate in either fresh or cooled semen. Per cent Motility Significantly,decreased (P < .01) in cooled semen. In addition, high concentrations of gentamicin Sulfate (2000 mug/ml) decreased (p < .01) percent Motility in fresh semen. Mis effect was more pronounced in cooled semen in presence of 500 or 2000,mug/ml of gentamicin sulfate. It is concluded that high concentrations of gentamicin sulfate appear to be detrimental to sperm. motility, but not velocity.