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 co llected once from all stallions from October 1997 through March 1998. Immed iately after collection, semen was extended with a dried-Skim Milk based ex tender (pH = 7.0) Containing either 0, 500 or 2000, mug/ml gentamicin sulfa te to a final concentration of 10 X 10(6) spermatoza/ml. Average path veloc ity decreased ( p < .01) in cooled semen (44.2 +/-2.3 mum/sec) when compare d 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 c ent Motility Significantly,decreased (P < .01) in cooled semen. In addition , high concentrations of gentamicin Sulfate (2000 mug/ml) decreased (p < .0 1) percent Motility in fresh semen. Mis effect was more pronounced in coole d semen in presence of 500 or 2000,mug/ml of gentamicin sulfate. It is conc luded that high concentrations of gentamicin sulfate appear to be detriment al to sperm. motility, but not velocity.