Department of Clinical Studies - New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Pennsylvania, Kennett, USA.
Select Breeders Service, Chesapeake, Maryland, USA.
Reprod Domest Anim. 2023 Feb;58(2):349-357. doi: 10.1111/rda.14294. Epub 2022 Nov 25.
Neat stallion semen can contain a variety of microorganisms, some of which may impair sperm quality and/or cause infection of the mares' reproductive tract. For this reason, antibiotics are commonly added to semen extenders. A combination of gentamicin, tylosin, lincomycin and spectinomycin (GTLS) has been recommended for use, but there are no reports on the use of this mixture in equine semen extender. Penicillin and amikacin (PA) are safe for preserving sperm quality while effectively controlling bacterial growth in equine cooled stored semen, but data on frozen semen are scarce. Therefore, a bioequivalence study was performed to assess the bactericidal activity of GTLS and PA in equine frozen semen. Nine mature, healthy stallions were used in the study. Split ejaculates were processed using media without antibiotics (Control) or with different antibiotics. For the GTLS group, centrifugation medium and freezing extender were prepared with gentamicin 250 μg/ml, tylosin 50 μg/ml, lincomycin 150 μg/ml and spectinomycin 300 μg/ml. For the PA group, the centrifugation medium was prepared with potassium penicillin G (PPG) 1200 units/ml and the freezing extender was prepared with PPG 1200 units/ml and amikacin 500 μg/ml. Semen processed in extenders without antibiotics had higher (p < .005) bacterial loads throughout all cryopreservation processing steps than semen samples processed using antibiotics. There were no differences in semen bacterial load after centrifugation, 15 and 30 min after final extension, and after thawing between GTLS and PA groups, but PA had faster (p < .05) kill-time kinetics than GTLS. Only minor differences in sperm kinetic parameters were observed among groups. In conclusion, this study demonstrated bioequivalence between GTLS and PA in mitigating end-point bacterial loads. Prudent concentrations of the antibiotic mixtures evaluated in this study can be considered both effective and sperm-safe for equine frozen semen.
健康的种马精液中可能含有多种微生物，其中一些可能会降低精子质量和/或导致母马生殖道感染。出于这个原因，通常会在精液稀释液中添加抗生素。已推荐使用庆大霉素、泰乐菌素、林可霉素和壮观霉素（GTLS）的组合，但没有关于该混合物在马属动物精液稀释液中使用的报道。青霉素和阿米卡星（PA）在保存精子质量的同时有效控制马属动物冷藏保存精液中的细菌生长，但关于冷冻精液的数据很少。因此，进行了一项生物等效性研究，以评估 GTLS 和 PA 在马属动物冷冻精液中的杀菌活性。研究中使用了 9 头成熟、健康的种马。将分离的精液用不含抗生素的培养基（对照）或不同抗生素处理。对于 GTLS 组，离心介质和冷冻稀释液用庆大霉素 250μg/ml、泰乐菌素 50μg/ml、林可霉素 150μg/ml 和壮观霉素 300μg/ml 制备。对于 PA 组，离心介质用青霉素钾（PPG）1200 单位/ml 制备，冷冻稀释液用 PPG 1200 单位/ml 和阿米卡星 500μg/ml 制备。在所有冷冻保存处理步骤中，不含抗生素的稀释液处理的精液的细菌负荷均高于（p<0.005）使用抗生素处理的精液样本。GTLS 和 PA 组在离心后、最终扩展后 15 和 30 分钟以及解冻后，精液的细菌负荷没有差异，但 PA 的杀灭时间动力学比 GTLS 更快（p<0.05）。各组间精子动力学参数仅有细微差异。综上所述，本研究证明了 GTLS 和 PA 在减轻终点细菌负荷方面具有生物等效性。在本研究中评估的抗生素混合物的谨慎浓度可被认为对马属动物冷冻精液既有效又安全。
