Comparing the Effect of Different Antibiotics in Frozen-Thawed Ram Sperm: Is It Possible to Avoid Their Addition?

Luis Anel-Lopez,Ana Carvajal,Jose R Altonaga,Rafael Montes-Garrido,Luis Anel,Paulino De Paz,Marta F Riesco,Cristina Ortega-Ferrusola,Juan C Boixo,Mercedes Alvarez,Marta Neila-Montero,César Chamorro

doi:10.3389/fvets.2021.656937

Luis Anel-Lopez, Ana Carvajal + Show 10 more

Open Access

https://doi.org/10.3389/fvets.2021.656937

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Abstract

It is crucial to perform a deep study about the most extensively used antibiotics in sperm extenders. Most of the protocols and concentrations used in ram are direct extrapolations from other species. It is important to establish species-specific antibiotic treatments to optimize their use and if it is possible to reduce the quantity. Previews studies have assessed some aspects of sperm quality in vitro, but this study aimed to go further and assess the effect of three different antibiotic treatments, which are the most extensively used, not only in sperm quality or assessing the inhibitory effect on bacterial growth but also assessing these important parameters of productivity such as fertility, prolificacy, fecundity, and sex-ratio during a freeze-thaw process. Gentamicyn (G) treatment showed the worst results, not only concerning sperm quality but also in the reproductive trials exhibiting a toxical effect at the experiment concentration, and being the most powerful inhibiting bacterial growth. For its part, Lincomicyn-spectinomycin (LS) showed similar results inhibiting bacterial growth but it did not show a detrimental effect either in sperm quality or in reproductive parameters. Penicillin-streptomycin (PS) showed good results in the sperm quality and in the reproductive in vivo trials, but it showed a very poor effect inhibiting bacterial growth probably due to some kind of antibiotic resistance. According to our results, there is not a significant positive relationship between the higher bacterial inhibitory activity of LS and PS samples, and the sperm quality respect Control samples (without antibiotics). In the case of G, which exhibited the most effective as antibacterial, we observed a toxic effect on sperm quality that could be translated on productivity parameters. Our results suggest that the bacterial contamination control in frozen-thawed semen may be possible without the use of antibiotics, although the effects of longer periods of cooling storage and different temperatures of storage need to be further investigated for animal semen. At this point, a reflection about a drastic reduction in the use of antibiotic treatments in sperm cryopreservation is mandatory, since freezing conditions could keep sperm doses contamination within the levels recommended by regulatory health agencies.

Highlights

Semen collection and sperm manipulation are not sterile processes, and bacterial contamination, especially environmental and non-pathological and pathological species, of sperm samples cannot be avoided [1, 2]
A total of 10 genera and 16 bacterial species (Figure 4) were identified with Pseudomonas (3 isolates) and Staphylococcus (3 isolates) as the most common genera followed by E. coli
Semen is normally colonized by a high variety of microorganisms that may reduce sperm quality

Summary

Introduction

Semen collection and sperm manipulation are not sterile processes, and bacterial contamination, especially environmental and non-pathological and pathological species, of sperm samples cannot be avoided [1, 2]. The final ejaculate collected is usually contaminated at least with bacteria from the technician, artificial vagina, penis, and prepuce In this way, bacterial contamination could affect the sperm quality and the final yield of the production. To prevent disease transmission in most domestic species, the addition of antibiotics to sperm extenders is mandatory in the European Union and so common in other countries outside [9]. Many studies have demonstrated the beneficial effect of antibiotics inhibiting the bacterial proliferation in the sperm samples during their storage [1, 16,17,18] Most of these studies have been carried out in different species than ram, without species specific studies, which could generate unexpected effects on relevant production aspects such as fertility, prolificacy, fecundity, or sex-ratio. To get a deep knowledge about the effects of antibiotics on the sperm quality and in the future production of the sperm doses is very important to optimize protocols and to reduce the use of antibiotics since the antimicrobial resistance supposes a global and serious danger for the human or animal health and for the economics [23]

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