Comparison of four antibiotics for inactivating leptospires in bull semen diluted in egg yolk extender and experimentally inoculated with Leptospira santarosai serovar guaricura

Abstract

Inactivation of leptospires in pools of semen from three Holstein Friesian bulls, collected in an artificial vagina, was investigated. Spermatic concentration was adjusted in egg yolk citrate extender, submitted to the following treatments: A (control; without antibiotics); B (penicillin, 1,000 UI/mL - streptomycin, 1,000 µg/mL); C (amoxicillin, 1,000 µg/mL); D (ceptiofur sodium, 1,000 µg/mL); E (amoxicillin 1,000 µg/mL - ceptiofur sodium 1,000 µg/mL). Leptospires (2.0 x 106 leptospires/mL) were added into the diluted semen. Recovery of leptospires was obtained in modified EMJH semi-solid medium with and without antibiotics. The antibiotics in the concentrations used did not affect means of percentage of progressive motility and individual progressive motility of spermatozoids. Penicillin-streptomycin presented the best results in leptospire inactivation (97.1%). Amoxicillin, ceptiofur sodium and their combination at the concentrations studied presented poor results: 59.29%; 32.5% and 60.36% of inactivation, being less effective in leptospire inactivation than penicillin-streptomycin.