Effect of marbofloxacin on mycoplasma carrier state and sperm quality in goat bucks

The presence of goat males carriers of the main causal agents of contagious agalactia, Mycoplasma agalactiae (Ma) and Mycoplasma mycoides subsp. capri (Mmc), is a high risk factor for the spread of the infection in artificial insemination centres. The present study was designed to assess the efficacy of a 5 day course of marbofloxacin given intramuscularly (2 mg kg−1 day−1) in terms of its capacity to reverse the carrier state of goat buck populations naturally infected with one or both mycoplasmas (Mmc, n = 25; Mmc + Ma, n = 2). Before and after treatment, ear swabs and semen samples were culture- and PCR-checked for both mycoplasmas. We also evaluated the impact of this treatment on semen quality (sperm count, motility and daily sperm production) by monitoring these variables of 594 semen samples collected during pre- and post-treatment periods of 48 days each. All bucks examined tested positive for the presence of Ma and Mmc before and after treatment though Mycoplasma spp. never was identified in semen. Sperm motility was significantly reduced in response to treatment (from 72.9% to 56.9%), although some recovery was observed at the end of the study (40 days after treatment). Ejaculate volume and concentration remained unchanged throughout the study. Our findings indicate that systemic marbofloxacin therapy is unable to eliminate mycoplasmas from the external auditory canal of male goats, and that it also causes a transient detrimental effect on sperm motility. Other strategies to control the presence of mycoplasma carriers in goat artificial insemination centres need to be assessed.