Effects of amikacin sulfate on the motility of stallion and bull spermatozoa at different temperatures and intervals of storage.

Because microfloral content of stallion semen tends to be high, and strains may be resistant to commonly used antibiotics, amikacin was tested with stallion semen and compared with bull semen. Nine ejaculates to stallion semen were incubated at 37 C in egg yolk-tris extender for 0, 2, 4, 6, 8 and 10 h in the presence of amikacin concentrations of 0, 50, 100, 250, 500, 1,000 and 10,000 microgram/ml, with penicillin and penicillin-streptomycin as controls. Averaged over all incubations, spermatozoal motility was 44, 48, 49, 46, 45, 45 and 19%, for increasing concentrations of amikacin, compared with 52 and 47% for penicillin and penicillin-streptomycin controls. The 10,000 microgram/ml concentration of amikacin was the only treatment that suppressed sperm motility (P less than .01). Amikacin (0, 50, 100, 250, 500, 1,000 2,500, 5,000 and 10,000 microgram/ml) and 1,000 IU of penicillin G plus 1,000 microgram of streptomycin/ml or 10,000 IU of penicillin G/ml were added to nine ejaculates of bull semen stored at 4 C in egg yolk-tris extender, and evaluated after 0, 1, 3, 5 and 7 d. The percentage of motile spermatozoa, with increasing levels of amikacin, was 66, 67, 66, 64, 67, 68, 74, 68 and 53%, respectively. Amikacin, at 2,500 microgram/ml, resulted in the highest (P less than .01) motility compared to the other levels of antibiotics after 7 d storage. Both 10,000 microgram of amikacin and 10,000 IU of penicillin G/ml depressed (P less than .01) the mean percentage of motile bull spermatozoa. These studies demonstrate that high concentrations of amikacin can be added to stallion and bull semen without depressing motility of spermatozoa.