Inclusion of supplemental antibiotics (amikacin - penicillin) in a commercial extender for stallion semen: Effects on sperm quality, bacterial growth, and fertility following cooled storage

摘要

In this study, the effectiveness of supplementing INRA-96 (R) extender (INRA-Control; original antibiotic formulation: potassium penicillin G = 38 mu g/mL; gentamicin sulfate = 105 mu g/mL; amphotericin B = 0.315 mu g/mL) with amikacin sulfate and potassium penicillin G (AP) was determined. In Exp. 1, two sources of amikacin (INRA-AP-Sigma or INRA-AP-GoldBio) in combination with penicillin G were compared with ticarcillin/clavulanate (INRA-Tim) or no-supplemental antibiotics (INRA-Control) to examine effects on sperm quality and commensal bacterial growth. No differences were detected in semen quality among treatments after 30 min of exposure (Time 30min) or 24 h of cooled storage (Time 24 h; P > 0.05); however, no differences in sperm quality were detected among treatment groups at Time 24 h (P > 0.05). In Exp. 3, a breeding trial was conducted to determine the effect of adding a high dose of AP (AP-5000) to INRA-96 (R) extender on resulting pregnancy rates of mares bred with cool-stored semen (Time 24 h). Numerical, but not statistical differences, were observed in pregnancy rates between the mares bred with INRA-Control (6/11; 55%) or INRA-AP-500 0 (9/11; 82%; P > 0.05). Supplementation of INRA-96 (R) extender with two different concentrations of AP (AP-1000 or AP-5000) was tested in two clinical cases of stallions where semen was moderately to heavily contaminated with Pseudomonas aeruginosa, or both Klebsiella pneumoniae and Pseudomonas aeruginosa. In both cases, addition of AP resulted in a considerable decrease on bacterial growth in cool-stored semen when compared to the use of the original INRA-96 (R) extender without supplemental antibiotics. In conclusion, the addition of amikacin sulfate and potassium penicillin G to INRA-96 (R) extender allowed for effective control of commensal bacteria without affecting sperm quality. Higher doses of amikacin and penicillin can be safely added to INRA-96 (R) extender to improve the antibacterial activity of this extender against commensal, and potentially pathogenic bacteria, while sperm quality and fertility of cooled semen remains unaffected. Based on the results of the present study, we currently recommend that INRA-96 (R) extender can be safely supplemented with amikacin/penicillin by using a conventional dose of 1000 mu g/mL-1000 IU/mL as a prophylactic measure in cases where contamination of the ejaculates with commensal bacteria is evident. Alternatively, a high dose (5000 mu g/mL - 5000 IU/mL) can be used as a control method for potentially pathogenic bacteria. (C) 2020 Elsevier Inc. All rights reserved.