Boar Semen Bacterial Contamination in Italy and Antibiotic Efficacy in a Modified Extender

Antimicrobial peptides and proteins as alternative antibiotics for porcine semen preservation

BACKGROUND

Antimicrobial resistance (AMR) is nowadays a major emerging challenge for public health worldwide. The over- and misuse of antibiotics, including those for cell culture, are promoting AMR while also encouraging the research and employment of alternative drugs. The addition of antibiotics to the cell media is strongly recommended in sperm preservation, being gentamicin the most used for boar semen. Because of its continued use, several bacterial strains present in boar semen have developed resistance to this antibiotic. Antimicrobial peptides and proteins (AMPPs) are promising candidates as alternative antibiotics because their mechanism of action is less likely to promote AMR. In the present study, we tested two AMPPs (lysozyme and nisin; 50 and 500 µg/mL) as possible substitutes of gentamicin for boar semen preservation up to 48 h of storage.

RESULTS

We found that both AMPPs improved sperm plasma membrane and acrosome integrity during semen storage. The highest concentration tested for lysozyme also kept the remaining sperm parameters unaltered, at 48 h of semen storage, and reduced the bacterial load at comparable levels of the samples supplemented with gentamicin (p > 0.05). On the other hand, while nisin (500 µg/mL) reduced the total Enterobacteriaceae counts, it also decreased the rapid and progressive sperm population and the seminal oxidation-reduction potential (p < 0.05).

CONCLUSIONS

The protective effect of lysozyme on sperm function together with its antimicrobial activity and inborn presence in body fluids, including semen and cervical mucus, makes this enzyme a promising antimicrobial agent for boar semen preservation.

Antibiotics in semen extenders - a multiplicity of paradoxes

Addition of antibiotics to semen extenders was taken for granted for many years, from the time that commercial artificial insemination in livestock first began many decades ago. However, there is now a growing realisation that this non-therapeutic utilisation of antibacterial agents is contrary to current recommendations for prudent use that medical and veterinary professionals are advised to follow. Furthermore, antibiotics are not benign, having negative effects on sperm samples, the inseminated female, personnel and potentially the environment. The purpose of this review is three-fold: to highlight the fact that antibiotics are used in semen extenders, with the result that considerable amounts are used globally in animal breeding, to review recent studies on the negative aspects of using antibiotics for this purpose, and to look at possible alternatives. Recent changes in the legislation regarding semen extenders occurred in some, but not all, countries, leaving question marks for semen producers as to whether antibiotics should be added to semen extenders or not.

Strategies for Bacterial Eradication from Human and Animal Semen Samples: Current Options and Future Alternatives

The primary role of semen processing and preservation is to maintain a high proportion of structurally and functionally competent and mature spermatozoa, that may be used for the purposes of artificial reproduction when needed, whilst minimizing any potential causes of sperm deterioration during ex vivo semen handling. Out of a multitude of variables determining the success of sperm preservation, bacterial contamination has been acknowledged with an increased interest because of its often unpredictable and complex effects on semen quality. Whilst antibiotics are usually the most straight-forward option to prevent the bacterial contamination of semen, antimicrobial resistance has become a serious threat requiring widespread attention. As such, besides discussing the consequences of bacteriospermia on the sperm vitality and the risks of antibiotic overuse in andrology, this paper summarizes the currently available evidence on alternative strategies to prevent bacterial contamination of semen prior to, during, and following sperm processing, selection, and preservation. Alternative antibacterial supplements are reviewed, and emphasis is given to modern methods of sperm selection that may be combined by the physical removal of bacteria prior to sperm preservation or by use in assisted reproductive technologies.

Bacteriospermia and its antimicrobial resistance in relation to boar sperm quality during short-term storage with or without antibiotics in a tropical environment

BACKGROUND

In tropical environments, boar semen is prepared either from a boar on the same farm as the sow herd or collected in semen collection centers and then transported to other farms. Thus, the semen doses can be used for artificial insemination either immediately or preserved for 2-3 days. The present study investigated the bacteriospermia and its antimicrobial resistance in relation to boar sperm quality during short-term storage in semen extender with or without antibiotics in Thailand. M&M: In total, 20 Duroc ejaculates were collected. Each ejaculate was diluted in Beltsville Thawing Solution extender either with 0.25 g of gentamicin per liter (ANTIBIOTIC) or without gentamicin (NO-ANITIBIOTIC) to create semen doses containing 3,000 × 10⁶ sperm/100 mL. These were stored at 17 °C for 4 days. Semen characteristics and total bacterial count (CFU per mL, log₁₀) were measured after collection and during storage.

RESULTS

Sperm viability was decreased by 6.4% for every 1.0 log₁₀ increase in total bacterial count (p = 0.026) and Staphylococcus spp. were the most frequently isolated across ejaculates. Throughout the 4 days of storage, sperm motility, viability and acrosome integrity in the ANTIBIOTIC group were higher than those in the NO-ANTIBIOTIC group (p < 0.05), while the total bacterial count was lower (1.9 ± 0.1 versus 3.9 ± 0.1 log₁₀, respectively; p < 0.001). Without antibiotic supplementation, the total numbers of bacteria counted on days 2 and 3 of storage were higher than those determined on days 0 and 1 (p < 0.001). Differences in semen quality were detected on days 2 and 3 between the NO-ANTIBIOTIC and ANTIBIOTIC groups in high-viability semen (p < 0.05). However, no differences in sperm quality between the NO-ANTIBIOTIC and ANTIBIOTIC groups were detected in the low-viability semen on each storage day (p > 0.05). On the last day of preservation, Globicatella sanguinis (57.2%), Delftia acidovorans (18.9%) and Micrococcus spp. (5.9%) remained as the top three most abundant contaminants in the semen with antibiotic.

CONCLUSION

Our findings contribute new insights toward reducing antibiotics as well as rational antibiotic use in the boar AI industry. The growth of bacteria was significantly greater only after 2 days of preservation in the semen without antibiotic. For semen doses diluted from highly viable ejaculates, it is possible to store for 2 days without any antibiotic supplementation. Moreover, bacterial counts increased at the end of storage in the presence of gentamycin, suggesting the loss of bacteriostatic properties of gentamicin to the growth of bacteria during storage.

Single layer centrifugation (SLC) for bacterial removal with Porcicoll positively modifies chromatin structure in boar spermatozoa

The storage of boar semen samples at 17 °C for artificial insemination (AI) doses enables the proliferation of the bacteria, making antibiotics necessary. This can contribute to the development of antimicrobial resistance (AMR). This study tested bacterial presence and sperm chromatin structure after using a low-density colloid (Porcicoll) as an antibiotic alternative to eliminate bacteria. Ejaculates (8 boars, 3 ejaculates each) were split as control and low-density colloid centrifugation (single layer centrifugation, SLC, 20%, and 30% Porcicoll) into 500 ml tubes. Analyses were carried out at days 0, 3, and 7 (17 °C) for microbial presence and sperm chromatin structure analysis: %DFI (DNA fragmentation) and %HDS (chromatin immaturity), monobromobimane (mBBr; free thiols and disulfide bridges), and chromomycin A3 (CMA3; chromatin compaction). Besides comparing bacterial presence (7 species identified) and chromatin variables between treatments, the associations between these sets of variables were described by canonical correlation analysis (CCA). Results showed a significant decrease of some bacteria or a complete removal after SLC (especially for P30). SLC also caused a decrease of %HDS and an increase of disulfide bridges and low and medium mBBr populations, suggesting the removal of immature sperm (poor chromatin compaction). CCA showed an association pattern compatible with the degradation of sperm chromatin parameters with bacterial contamination, especially Enterobacteria, P. aeuriginosa, and K. variicola. In conclusion, bacterial contamination affects sperm chromatin beyond DNA fragmentation; SLC with low-density colloid not only removes bacteria from boar semen, but also chromatin structure is enhanced after selection.

Antimicrobial activity of cell free supernatants from probiotics inhibits against pathogenic bacteria isolated from fresh boar semen

The use of antibiotics with semen extender appears to be a practical solution to minimise bacterial growth in fresh boar semen preservation. Unfortunately, the excessive use of antibiotics promotes antimicrobial resistance (AMR). This becomes a worldwide concern due to the antimicrobial resistance genes transmitted to animals, environment, and humans. Probiotics are one of the alternative methods to reduce antibiotic use. They could inhibit pathogenic bacteria by producing antimicrobial substances in cell free supernatants (CFS). Nevertheless, there is no comprehensive study undertaken on inhibitory activity against pathogenic bacteria isolated from boar semen origin. Our study investigated the efficacy of CFS produced from selected probiotics: Bacillus spp., Enterococcus spp., Weissella spp., Lactobacillus spp., and Pediococcus spp. inhibiting pathogenic bacteria isolated from fresh boar semen. Besides, the semen-origin pathogenic bacteria are subjected to identification, antimicrobial resistance genes detection, and antibiotic susceptibility test (AST). Pseudomonas aeruginosa, Escherichia coli, and Proteus mirabilis are the most common pathogens identified in boar semen with resistance to numerous antibiotics used in pig industry. The CFS with its antimicrobial peptides and/or bacteriocin constituent derived from selected probiotics could inhibit the growth of pathogenic bacteria carrying antimicrobial resistance genes (mcr-3 and int1 genes). The inhibition zones for Pseudomonas aeruginosa, Escherichia coli, and Proteus mirabilis provided more efficient results in the CFS derived from Lactobacillus spp. and Pediococcus spp. than those of the CFS produced from Enterococcus spp., Weissella spp. and Bacillus spp., respectively. It is worth noted that as the incubation time increased, the antibacterial activity decreased conversely. Our results on CFS with its antimicrobial peptides and/or bacteriocin constituent inhibits semen-origin pathogenic bacteria guide the direction as a promising alternative method used in the semen extender preservation of the pig industry.

Low-density colloid centrifugation removes bacteria from boar semen doses after spiking with selected species

Single-layer centrifugation (SLC) with a low-density colloid is an efficient method for removing contaminating microorganisms from boar semen while recovering most spermatozoa from the original sample. This study tested the performance of this technique, using 50-ml tubes, by spiking commercial semen doses prepared without antibiotics with selected bacterial species followed by storage at 17 °C. The doses were spiked up to 10²/ml CFU (colony forming units) of the bacteria Burkholderia ambifaria, Pseudomonas aeruginosa, and Staphylococcus simulans. The semen was processed by SLC (15 ml of sample and 15 ml of colloid) with the colloid Porcicoll at 20% (P20) and 30% (P30), with a spiked control (CTL) and an unspiked control (CTL0), analyzing microbiology and sperm quality on days 0, 3 and 7. SLC completely removed B. ambifaria and S. simulans, considerably reducing P. aeruginosa and overall contamination (especially P30, ∼10⁴ CFU/ml of total contamination on day 7, median). Sperm viability was lower in P20 and P30 samples at day 0, with higher cytoplasmic ROS. Still, results were similar in all groups on day 3 and reversed on day 7, indicating a protective effect of SLC (possibly directly by removal of damaged sperm and indirectly because of lower bacterial contamination). Sperm chromatin was affected by the treatment (lower DNA fragmentation and chromatin decondensation) and storage (higher overall condensation on day 7 as per chromomycin A3 and monobromobimane staining). In conclusion, SLC with low-density colloids can remove most bacteria in a controlled contamination design while potentially improving sperm quality and long-term storage at practical temperatures.

Antimicrobials in a rabbit semen extender: effects on reproduction

The use of fluoroquinolone antibiotics was legally restricted by the European Commission in March 2019. Since the extender for rabbit semen Galap® contained this antibiotic, it became necessary to modify it. The purpose of this study was to search for another  molecule, based on its antimicrobial activity and also on the conservation, motility and fertility of semen diluted with the new extender. Several bacterial strains were isolated from 10 poor-quality ejaculates, including Enterococcus spp., Staphylococcus aureus and Proteus spp. They were then tested for antimicrobial susceptibility. Out of 15 antibiotics evaluated, gentamicin was the one targeting such bacteria. In vivo tests were then carried out to assess the effects of this antibiotic change on sperm parameters. Up to 26 pools of good quality semen (total motility >70%) were diluted in original Galap® or in this extender with gentamicin. Ejaculates were analysed on the day (D) of collection and up to 6 d of storage at +17°C. After 24 h storage, the motility in the new extender was reduced by 7.7% compared to the original; this decrease did not worsen by storing. After 6 d of storage, no difference between the two media was detected. A total of 360 females were then inseminated with pools of 4 to 5 good quality semen diluted 1:10 in both extenders, following the routine protocol of rabbit semen processing centres. There was no difference in female fertility or prolificacy between both formulations. In conclusion, these preliminary results suggest that the addition of gentamicin to this extender is useful andalso has no adverse effect on fertility or prolificacy.

Curcumin Attenuates Damage to Rooster Spermatozoa Exposed to Selected Uropathogens

Artificial insemination, as an essential pillar of the modern poultry industry, primarily depends on the quality of semen collected from stud roosters. Since the collection and storage of ejaculates is not a sterile process, antimicrobial agents have become essential supplements to semen extenders. While the use of traditional antibiotics has been challenged because of rising bacterial resistance, natural biomolecules represent an appealing alternative because of their antibacterial and antioxidant properties. As such, this study strived to compare the effects of 50 μmol/L curcumin (CUR) with 31.2 µg/mL kanamycin (KAN) as a conventional antibiotic on rooster sperm quality in the presence of Salmonella enterica, Escherichia coli and Pseudomonas aeruginosa. Changes in sperm structural integrity and functional activity were monitored at 2 and 24 h of culture. Computer-assisted semen analysis revealed significant sperm motility preservation following treatment with KAN, particularly in the case of Salmonella enterica and Pseudomonas aeruginosa (p < 0.001) after 24 h. On the other hand, CUR was more effective in opposing ROS overproduction by all bacteria (p < 0.05), as determined by luminol-based luminometry, and maintained sperm mitochondrial activity (p < 0.001 in the case of Salmonella enterica; p < 0.05 with respect to Escherichia coli and Pseudomonas aeruginosa), as assessed by the fluorometric JC-1 assay. The TUNEL assay revealed that CUR readily preserved the DNA integrity of rooster sperm exposed to Salmonella enterica (p < 0.01) and Escherichia coli (p < 0.001). The bacteriological analysis showed higher efficiency of KAN in preventing the growth of all selected bacterial species (p < 0.0001) as opposed to CUR. In conclusion, CUR provided protection to rooster spermatozoa against alterations caused by uropathogens, most likely through its antioxidant activity. Hence, CUR supplementation to poultry semen extenders in combination with properly selected antibacterial substances may become an interesting strategy in the management of bacterial contamination during semen storage.

Bacteriospermia - A formidable player in male subfertility

Bacterial colonization of male reproductive tissues, cells, and fluids, and the subsequent impact of bacteria on the sperm architecture, activity, and fertilizing potential, has recently gained increased attention from the medical and scientific community. Current evidence strongly emphasizes the fact that the presence of bacteria in semen may have dire consequences on the resulting male fertility. Nevertheless, the molecular basis underlying bacteriospermia-associated suboptimal semen quality is sophisticated, multifactorial, and still needs further understanding. Bacterial adhesion and subsequent sperm agglutination and immobilization represent the most direct pathway of sperm-bacterial interactions. Furthermore, the release of bacterial toxins and leukocytic infiltration, associated with a massive outburst of reactive oxygen species, have been repeatedly associated with sperm dysfunction in bacteria-infested semen. This review serves as a summary of the present knowledge on bacteriospermia-associated male subfertility. Furthermore, we strived to outline the currently available methods for assessing bacterial profiles in semen and to outline the most promising strategies for the prevention and/or management of bacteriospermia in practice.

Boar Semen Contamination: Identification of Gram-Negative Bacteria and Antimicrobial Resistance Profile

Simple Summary

Boar semen can contain many bacterial species, some of which can have a negative impact upon the quality of the semen, as well as on the sows’ reproductive capacity. Semen contamination may occur at time of collection or during semen processing. The aim of this study was to identify gram-negative bacteria that appear in boar semen and to establish models of antimicrobial resistance of isolated gram-negative bacteria. Semen doses examined contained bacterial species with a known negative effect on sows’ reproductive tracts (Pseudomonas, Enterobacter, Klebsiella, E. coli), and more than half of these isolates were resistance to gentamycin (56.52%) and penicillin (58.69%) antimicrobials commonly used in boar semen extenders. This work proved the presence of pathogenic multiple resistant bacteria in semen, and therefore, we highly recommend periodic microbiological screening of bacteriospermia in boars to avoid the use of low-quality semen in the pig industry.

Abstract

Bacterial contamination of boar semen occurs with some frequency in artificial insemination centers and may have a negative effect on the quality of the semen as well as on the sows’ reproductive capacity. Normally, the source of bacterial contamination in pig seminal doses is the own boar. However, distilled water or laboratory equipment used to elaborate the seminal doses can be an important source of bacterial contamination. This study focused on the identification of gram-negative bacteria in boar semen, and impact on the quality of ejaculates obtained from boar, as well as on the establishment of antimicrobial resistance patterns of isolated gram-negative bacteria. Semen samples were collected from 96 boars, ranging in age from 12–36 month, from three artificial insemination centers from the North-West of Romania. Bacterial species were identified by two methods: matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry and API 20 E (BioMerieux, France). The main bacteria isolated from the doses diluted semen were gram-negative bacteria (47.91%), with a majority of the contaminant bacteria belonging to the family Enterobacteriaceae: Seratia marcescens 19.56%, Proteus mirabilis 15.21% and Escherichia coli 10.86% and to the family Pseudomonaceae: Ralstonia picketii 17.39%, Burkholderia cepacia 10.86%, Pseudomonas aeruginosa 8.69%, and Pseudomonas fluorescens 4.34%, respectively. More than half of these isolates (56.52%) were resistant to gentamycin and 58.69% were resistant to penicillin. These antibiotics are very frequently added in sperm diluent in the centers for the processing of sperm from boars in Romania. Regular monitoring for bacterial contamination is an important aspect of a control program.

Core Microbiome of Slovak Holstein Friesian Breeding Bulls' Semen

Simple Summary

The aim of this study was to characterize the bacterial profile of semen collected from Holstein Friesian breeding bulls via a high-throughput sequencing approach for a 16S rRNA gene variability analysis. A total of 55 fresh semen samples of sexually mature breeding bulls were used in the study. They were gathered from Holstein Friesian breeding bulls at Slovak Biological Services in Nitra, Slovak Republic. To amplify the V4 region of the 16S rRNA bacterial gene, universal primers 515F and 806R enhanced by a 6 bp barcode identification sequence were used. The 16S rRNA high-throughput sequencing strategy was used. Two microbial clusters were identified among the analyzed samples—the first cluster was based on Actinobacteria and Firmicutes, while the second cluster contained a high prevalence of Fusobacteria.

Abstract

Bacterial contamination of semen is an important factor connected to the health status of bulls that may significantly affect semen quality for artificial insemination. Moreover, some important bovine diseases may be transmitted through semen. Up to now, only a very limited number of complex studies describing the semen microbiome of bulls have been published, as many bacteria are hard to cultivate using traditional techniques. The 16S rRNA high-throughput sequencing strategy allows for the reliable identification of bacterial profiles of bovine semen together with the detection of noncultivable bacterial species. Fresh samples from Holstein Friesian breeding bulls (n = 55) were examined for the natural variability in the present bacteria. Semen doses were selected randomly from Slovak Biological Services in Nitra, Slovak Republic. The most predominant phyla within the whole dataset were Firmicutes (31%), Proteobacteria (22%), Fusobacteria (18%), Actinobacteria (13%) and Bacteroidetes (12%). Samples of semen were divided into two separate clusters according to their microbiome compositions using a cording partition around a medoids analysis. Microbiomes of the first cluster (CL1) of samples (n = 20) were based on Actinobacteria (CL1 average = 25%; CL = 28%) and Firmicutes (CL1 = 38%; CL2 = 27%), while the second cluster (CL2; n = 35) contained samples characterized by a high prevalence of Fusobacteria (CL1 = 4%; CL2 = 26%). Some important indicator microbial groups were differentially distributed between the clusters.

The Efficiency of Selected Extenders against Bacterial Contamination of Boar Semen in a Swine Breeding Facility in Western Slovakia

Simple Summary

This study evaluated the efficiency of selected semen extenders to prevent bacterial overgrowth in boar ejaculates stored for 72 h. Among the identified bacterial isolates, Escherichia coli and Pseudomonas aeruginosa were the most prevailing species. While all extenders supplemented with antibiotics ensured a satisfactory sperm vitality during the storage period, neither of them was able to achieve a complete elimination of bacteria from extended semen. Furthermore, a number of bacterial isolates exhibited resistance to several antibiotics chosen for the microbial susceptibility test (e.g., tigecyklin and ciprofloxacin).

Abstract

Bacteriospermia has become a serious factor affecting sperm quality in swine breeding, this is why antibiotics (ATBs) are a critical component of semen extenders. Due to ever-increasing antimicrobial resistance, the aim of this study was to assess the efficiency of selected commercially available semen extenders to prevent a possible bacterial contamination of boar ejaculates. Three Androstar Plus extenders containing different combinations of antibiotics were used to process ejaculates from 30 healthy Duroc breeding boars. Androstar Plus without antibiotics was used as a control. The extended samples were stored at 17 °C for 72 h. Sperm motility, viability, mitochondrial activity, DNA integrity and oxidative profile of each extended sample were assessed following 24 h, 48 h and 72 h. Furthermore, selective media were used to quantify the bacterial load and specific bacterial species were identified with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. The results indicate that semen extenders enriched with ATBs ensured a significantly higher preservation of the sperm quality in comparison to the ATB-free control. The total bacterial count was significantly decreased in the extenders supplemented with ATBs (p < 0.001), however gentamycin alone was not effective enough against Gram-positive bacteria, while a few colonies of Enterococcus hirae, Bacillus subtilis and Corynebacterium spp. were present in the samples extended in the presence of a triple combination of ATBs. In conclusion, we may suggest that semen extenders enriched in antibiotics were not able to fully eliminate the bacteria present in the studied samples. Furthermore, selection of suitable antibiotics for semen extension should be accompanied by adequate hygiene standards during the collection and handling of boar ejaculates.

Plant Extracts as Alternative Additives for Sperm Preservation

Sperm preservation is a crucial factor for the success of assisted reproductive technology (ART) in humans, livestock, and wildlife. Irrespective of the extender and the storage conditions used, semen handling and preservation negatively affect sperm quality. Moreover, oxidative stress, which often arises during semen storage, significantly reduces sperm function and compromises the sperm fertilizing ability by inducing oxidative damage to proteins, lipids, and nucleic acids. Plant extracts have recently emerged as a cheap and natural source of additives to preserve and enhance sperm function during semen storage. The present work provides an update on the use of these natural compounds as alternative additives for sperm preservation in 13 animal species, including humans. A detailed description of the effects of 45 plant species, belonging to 28 families, on sperm function during semen storage is presented. The plant material and extraction method employed, dosage, possible toxic effects, and antimicrobial properties are provided.

Semen quality and total microbial load: An association study in important Indian Goat breeds during different seasons

The invasion of the male urogenital tract by microorganisms, and its subsequent effects on sperm fertilising ability, has not been well discussed in bucks. The present study was conducted to assess the bacterial load in fresh semen of the 2-6 years old bucks. For conducting the experiment, semen ejaculates from 18 bucks (6 from each breed namely Jakhrana, Jamunapari and Barbari) were used. We collected 5 ejaculates from each buck in each season (Summer-April to June, Rainy-July to Sept and Winter-November to January). Semen was collected with the artificial vagina (AV) method, and separate AV was used for each buck every time. The semen collection frequency was once in a week. Immediately after initial evaluation, collected semen samples were transferred to the microbiology laboratory of the institute. Thereafter, the semen samples were subjected to bacteriological examination to assess the microbial load. The results of the current study indicate that the microbial load in the semen was significantly (p < 0.05) higher in the Jamunapari bucks and in aged bucks. Bacteriospermia in different seasons was not significantly varied; however, nonsignificant increase in microbial load during the rainy season was observed. Overall, the average bacterial load in the semen of Jamunapari, Barbari and Jakhrana bucks was found 540.50 ± 55.88 CFU/ml, 391.81 ± 46.33CFU/ml and 388.93 ± 44.71 CFU/ml respectively. No significant difference in bacterial counts in the subsequent ejaculates among bucks was observed. Moreover, correlation analysis revealed that the proportions of motility, viability, plasma membrane integrity and acrosomal integrity were negatively influenced by the increased bacterial contamination of buck semen.

Low density Porcicoll separates spermatozoa from bacteria and retains sperm quality

Antibiotics are added to semen extenders to control the growth of bacteria contaminating semen during collection but may contribute to the development of antibiotic resistance. An alternative would be physical separation of spermatozoa from bacteria. The objective of the present study was to evaluate two low densities of Porcicoll for removal of bacteria, and for their effect on sperm recovery and sperm quality. Semen was collected from boars at a commercial station. Aliquots of 8 extended ejaculates were subjected to colloid centrifugation through 20% Porcicoll (P20) and 30% Porcicoll (P30) in 500 mL tubes and then stored at 17 °C. Microbiological examination and sperm quality evaluation (computer assisted sperm analysis and flow cytometry) were carried out on controls and all colloid-selected samples immediately after preparation and again after storage for 3 and 7 days. The microorganisms found were mainly bacteria from the environment, gut or skin. There was a considerable reduction or complete removal of some bacteria by both colloids. Recovery rates were 86% for P20 and 81% for P30. Sperm quality was not adversely affected by colloid centrifugation on day 0, and thereafter showed a more gradual deterioration in colloid centrifuged samples than in controls, possibly due to lower bacterial contamination. There were no differences in sperm quality between the two colloid treatments. Thus, these results show that contaminating bacteria in semen can be controlled by centrifugation through low density colloids.

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

In this study, the effectiveness of supplementing INRA-96® extender (INRA-Control; original antibiotic formulation: potassium penicillin G = 38 μg/mL; gentamicin sulfate = 105 μg/mL; amphotericin B = 0.315 μg/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). At both time periods, commensal bacterial growth was significantly lower in Groups INRA-AP-GoldBio and INRA-AP-Sigma than in INRA-Tim or INRA-Control (P < 0.05). In Exp. 2, increasing doses of amikacin sulfate (GoldBio) plus potassium penicillin G (Sigma) - AP (AP-1000, 2000, 3000, 4000 or 5000 μg-IU/mL, respectively) were added to INRA-96® extender and their effects on sperm quality and commensal bacterial growth were evaluated at Time 30min and Time 24 h. Slight reductions in progressive motility and viability were observed at Time 30min in Groups AP-4000 and AP-5000 as compared to other treatment groups (P < 0.05); however, no differences in sperm quality were detected among treatment groups at Time 24 h (P > 0.05). At both time periods, commensal bacterial growth was significantly lower in Groups AP-3000, AP-4000 and AP-5000 than in AP-1000 and AP-2000 (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® 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-5000 (9/11; 82%; P > 0.05). Supplementation of INRA-96® 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® extender without supplemental antibiotics. In conclusion, the addition of amikacin sulfate and potassium penicillin G to INRA-96® 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® 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® extender can be safely supplemented with amikacin/penicillin by using a conventional dose of 1000 μg/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 μg/mL - 5000 IU/mL) can be used as a control method for potentially pathogenic bacteria.

Antimicrobial Resistance as a Problem for the Quality of Boar Semen

The aim of the study was to determine whether the bacteria from the environment and from the mucous membrane of the boar prepuce have antimicrobial resistance and whether the result obtained is similar/same to the bacteria that can be found in native boar semen. The study addresses the problem of the presence of primarily resistant bacterial strains in the boar sperm, which, due to their reduced sensitivity, cannot be suppressed by antibiotics used in the semen dilution agent, as well as to emphasize the importance of microbiological monitoring of the boar mucous membranes and ambient surfaces before and during their exploitation. Such an examination could contribute to the interchangeable design of the dilution agent for the boar semen relative to the antibiotic content.Resistant strains of bacteria from prepuce swabs and swabs taken from the facility, as well as from native boar semen were isolated. The presence of these bacteria affected the quality of the semen. In conclusion, it should be pointed out that bacterial monitoring of the prepuce and surface of the facility can indicate possible problems related to the quality of semen, and that the design of the dilution agent for boar semen should be adjusted to the established resistance of isolated bacteria.

Pharmacological Activity of Honeybush (Cyclopia intermedia) in Boar Spermatozoa during Semen Storage and under Oxidative Stress

Simple Summary

Nowadays, pig breeding is mostly conducted by artificial insemination using diluted semen stored for 1 to 5 days. During semen handling and storage, sperm quality usually declines, mainly because of oxidative stress and bacterial contamination. As cheap and natural sources of antioxidants, medicinal plants have become an alternative to the most common additives used in semen extenders. In this regard, several indigenous plants from Southern Africa have shown pharmacological activity in different animal cell types, although their effects on sperm cells have not been explored extensively. In the present study, we tested the effects of honeybush (Cyclopia intermedia) aqueous extract as a preservative of boar semen during 5 days of storage and under induced oxidative stress. Overall, this plant extract enhanced several sperm quality parameters and did not show any toxic effects. Supplementation with honeybush extract was able to improve the preservative properties of a long-term semen extender, thus confirming the beneficial use of plant extracts as natural additives for boar sperm.

Abstract

In recent decades, an increasing number of ethnopharmacological studies have been dedicated to medicinal plants from South African fynbos. Among these plants, honeybush (Cyclopia spp.) has become a popular tea, mainly due to its healthy properties and caffeine-free status. The antioxidant, antimutagenic, and antimicrobial properties of this plant have been reported in several cell types, but its effects on reproductive function are still unknown. Here, we assessed the effects of honeybush (Cyclopia intermedia) on boar sperm parameters under induced oxidative stress (Fe²⁺/ascorbate) and during five days of semen storage at 17 °C without oxidative stress. In both experiments, four concentrations (200, 50, 12.5, and 3.125 µg/mL) of fermented honeybush were tested. Our results show that honeybush enhances sperm parameters, and no toxic effects were observed at any of the tested extract concentrations. Interestingly, honeybush (12.5 µg/mL) improved the sperm motility and kinetic parameters, preserved the plasma membrane integrity, and reduced the lipid peroxidation in the samples exposed to Fe²⁺/ascorbate (p < 0.05). In the stored samples, positive effects of honeybush on sperm parameters (motility, kinetics, acrosome, and mitochondria) were observed from 48 h until 120 h of semen storage (p < 0.05). Our results clearly show the protective effects of honeybush on sperm samples, thus promoting its use as a natural source of antioxidants for boar semen.

Bacteriospermia and Sperm Quality of Cryopreserved Bull Semen Used in Artificial Insemination of Cows in South Wollo Zone, Ethiopia

The objectives of this trial were to estimate prevalence of bacteriospermia, to determine the bacterial load, and to isolate the types of bacteria as well as to assess the association between bacterial load and sperm quality traits in cryopreserved bull semen in field conditions in the South Wollo Zone. A total of 309 cryopreserved straws of semen from the Holstein Friesian (HF)-cross bull (n = 180 straws) and pure Jersey bull (n = 129 straws) were investigated. Bacteriological assessments of the presence of aerobic bacteria, estimation of bacterial count and bacterial isolation, as well as semen quality were performed. Aerobic bacterial contamination was prevalent in 38.8% of the semen straws. No significant difference in the prevalence of bacteriospermia was observed among bulls although the HF-cross bull had a higher prevalence (40.0%). But, significant difference in prevalence of bacteriospermia was found among semen ejaculates of the same bull. The risk of bacteriospermia in the HF-cross bull was higher (Odds ratio = 1.86, 95% CI = 0.168–20.26) compared to Jersey although not significant. Overall average bacterial load of 50.38 ± 16.29 colony-forming units (CFU)/ml (from nil to 1318.20 CFU/ml) was found. No significant difference in bacterial count among bulls and their ejaculates was observed. Moreover, correlation analysis revealed that the proportions of motility, live, and normal morphology were negatively influenced by an increase in the bacterial contamination of semen. In this study, three isolates of coagualse-negative Staphylococcus species and one isolate of Corynebacterium species were found. Average percentages of sperm motility (48.35 ± 1.23), live (66.08 ± 1.0), and normal morphology (80.62 ± 1.24) were observed. It was concluded that cryopreservation does not guarantee the quality of semen from bacterial contamination. Hence, meticulous care should be adopted to prevent contamination of semen by bacteria during collection, transportation, processing, and storage times.

Antibiotics Versus Natural Biomolecules: The Case of In Vitro Induced Bacteriospermia by Enterococcus Faecalis in Rabbit Semen

Male subfertility is a global issue in human reproduction as well as in animal reproduction. Bacterial infection and semen contamination are still widely overlooked. As the collection of ejaculates is not a sterile process, it is necessary to add antimicrobial agents to avoid a possible depreciation of semen samples. As traditionally used antibiotics have been questioned because of an ever-increasing bacterial resistance, natural bioactive molecules could offer an alternative because of their antibacterial and antioxidant properties. As such, we decided to compare the effects of selected natural biomolecules (resveratrol-RES, quercetin-QUE and curcumin-CUR) with routinely used antibiotics in animal biotechnologies (penicillin-PEN, gentamicin-GEN and kanamycin-KAN) on the rabbit sperm vitality in the presence of Enterococcus faecalis. Changes in the sperm structural integrity and functional activity were monitored at 0, 2, 4 and 6 h. Computer-assisted sperm analysis (CASA) was used for the assessment of spermatozoa motility. Production of reactive oxygen species (ROS) was evaluated using chemiluminiscence, while the mitochondrial membrane potential (ΔΨm) was examined using the JC-1 dye. Finally, the sperm chromatin dispersion (SCD) test was used to assess DNA fragmentation, and changes to the membrane integrity were evaluated with the help of annexin V/propidium iodide. The motility assessment revealed a significant sperm motility preservation following treatment with GEN (p < 0.001), followed by PEN and CUR (p < 0.01). QUE was the most capable substance to scavenge excessive ROS (p < 0.001) and to maintain ΔΨm (p < 0.01). The SCD assay revealed that the presence of bacteria and antibiotics significantly (p < 0.05) increased the DNA fragmentation. On the other hand, all bioactive compounds readily preserved the DNA integrity (p < 0.05). In contrast to the antibiotics, the natural biomolecules significantly maintained the sperm membrane integrity (p < 0.05). The microbiological analysis showed that GEN (p < 0.001), KAN (p < 0.001), PEN (p < 0.01) and CUR (p < 0.01) exhibited the strongest antibacterial activity against E. faecalis. In conclusion, all selected biomolecules provided protection to rabbit spermatozoa against deleterious changes to their structure and function as a result of Enterococcus faecalis contamination. Therefore, administration of RES, QUE and/or CUR to rabbit semen extenders in combination with a carefully selected antibacterial substance may be desirable.

Effects of sulfanilamide on boar sperm quality, bacterial composition, and fertility during liquid storage at 17°C

Sulfanilamide (SA) is an effective broad-spectrum antibacterial agent in human and veterinary medicine. The purpose of this study was to evaluate the effects of SA on boar sperm quality during liquid storage at 17°C and determine the optimal concentration of SA and its effects on bacterial growth, microbial composition, and maternal fertility. Boar ejaculates were diluted with a basic extender, containing different concentrations of SA, and stored in a 17°C incubator for 6 days. The sperm motility, plasma membrane integrity, and acrosome integrity were measured daily. The results showed that when the concentration of SA was 0.02 g/L, the sperm quality parameters were significantly higher than those of all other treatment groups (p < .05). We also monitored the bacterial growth and compared the differences in the microbial species between the 0.02 g/L SA group and the control by 16S rDNA sequencing. The results revealed that some bacteria, such as Staphylococcus and Pseudomonas, were considerably lower in the 0.02 g/L SA group than in the control group (p < .05). In addition, preserved semen was used for artificial insemination, and results showed that 0.02 g/L SA group had a higher litter size, and its pregnancy rate was 92.5%.

Effect of colloid centrifugation on boar sperm quality during storage and function in in vitro fertilization

Ejaculates contain a heterogeneous population of spermatozoa with differing ability to fertilize. It may be possible to reduce the numbers of spermatozoa required for artificial insemination or in vitro fertilization by selecting the sperm sub-population that possesses certain desired characteristics. This review describes what is meant by sperm quality, mentions different methods of sperm selection and then describes the effect of sperm selection by colloid centrifugation on boar sperm quality, both quality during storage and functionality in in vitro fertilization. Several versions of the technique known as Single Layer Centrifugation are available depending on the volume of ejaculate to be processed. Semen can be processed in volumes ranging from 0.25 to 150 mL, in suitably sized tubes. Processing small volumes of semen (0.25 mL on 1 mL colloid) is best done in a 15 mL tube, since the area of the interface between the semen and colloid is greater than in a 1.5 mL microcentrifuge tube. Potential uses of this processing technique are described, such as conservation breeding of rare breeds and removal of pathogens. Reducing the bacterial load in semen by single layer centrifugation though a low density colloid could provide an alternative to the use of antibiotics in semen extenders, and is an interesting development.

Removal of bacteria from boar semen using a low-density colloid

Antibiotics are added to semen extenders when preparing commercial semen doses for artificial insemination according to national and international guidelines. However, this addition of antibiotics represents non-therapeutic usage and could be contributing to the development of antibiotic resistance. Colloid centrifugation was shown to reduce the load of bacteria present in boar semen and was capable of removing all bacteria if performed directly after semen collection, albeit with some loss of spermatozoa. The present experiment was conducted with a low density colloid to investigate whether it was possible to separate all of the spermatozoa from seminal plasma i.e. without selection for robust spermatozoa, or whether this would have a detrimental effect on sperm quality. Ejaculates from nine boars were extended in Beltsville Thawing Solution without antibiotics and were transported to the laboratory for Single Layer Centrifugation (SLC) on modified Porcicoll i.e. at a low density (S). A further modification was that a sterile inner tube was included inside some of the 50 mL centrifuge tubes to facilitate harvesting of the sperm pellet (M). Aliquots of all samples (control, S and M) were cultured for bacterial quantification and identification using standard microbiological methods. Sperm quality was evaluated daily. Three of the C and M samples and five of the S samples did not contain any bacteria. Mean bacterial counts for the remaining samples (colony forming units/mL) were as follows: C 259 ± 216; S 30 ± 22; M 33 ± 15 (P < 0.01). Citrobacter spp., Staphylococcus simulans, Klebsiella variicola, Escherichia coli, Myroides odoratimimus, Proteus spp. and Enterococcus faecalis were identified in the control samples. There were marginal differences in sperm quality among treatments, with sperm velocity and linearity being higher in S and M samples than in C at all time points. However, sperm viability, capacitation and acrosome status were marginally better in controls than in S or M on day 0, but these differences disappeared during storage. Conclusions: centrifugation through a low density colloid can remove or reduce bacterial contamination in boar ejaculates without using antibiotics. Furthermore, it is possible to collect boar ejaculates without bacterial contamination by paying strict attention to hygiene.

Bacterial Contamination of Boar Semen and its Relationship to Sperm Quality Preserved in Commercial Extender Containing Gentamicin Sulfate

This study was designed to determine the degree and type of bacterial contamination in boar semen (79 ejaculates from Large White and Landrace boars) and its consequences for sperm quality during storage (27 extended semen samples, 16°C for five days) under practical conditions of artificial insemination (AI). The results revealed the presence of aerobic bacteria in 99% of the ejaculates (from 80 to 370 ×106 colony-forming units/mL). Most of the ejaculates contained two or three bacterial contaminants, while the Staphylococcus, Streptococcus, and Pseudomonas bacterial genera were most frequently isolated. Also detected were Enterobacter spp., Bacillus spp., Proteus spp., Escherichia coli, P. fluorescens, and P. aeruginosa. In general, the growth of certain bacterial types isolated prior to semen processing (Enterobacter spp., E. coli, P. fluorescens, and P. aeruginosa) was not discovered on different days of storage, but fluctuations (with a tendency towards increases) were found in the frequencies of Bacillus spp., Pseudomonas spp., and Staphylococcus spp. isolates up to the end of storage. Semen preserved for five days exhibited decreases in sperm motility and increases in the average number of total aerobic bacteria; this was associated with sperm agglutination, plasma membrane disruption, and acrosome damage. We inferred that, due to the different degrees and types of bacterial contaminants in the boar ejaculates, the inhibitory activity of some antimicrobial agents used in swine extenders (such as gentamicin sulfate) may be limited. Because such agents can contribute to the overgrowth of certain aerobic bacteria and a reduction in the quality of stored semen, procedures with high standards of hygiene and microbiological control should be used when processing boar semen.

Effect of Pseudomonas aeruginosa on sperm capacitation and protein phosphorylation of boar spermatozoa

Several studies have reported the detrimental effects that bacteriospermia causes on boar sperm quality, but little is known about its effects on IVC. Considering that, the present study sought to evaluate the effects of different concentrations of Pseudomonas aeruginosa on different indicators of capacitation status (sperm viability, membrane lipid disorder, sperm motility kinematics, and protein phosphorylation of boar spermatozoa) after IVC. Flow cytometry and computer assisted sperm analysis (CASA) revealed that the presence of P aeruginosa in boar sperm samples, mostly at concentrations greater than 10(6) CFU/mL, is associated with a significant (P < 0.05) decrease in the percentages of both sperm membrane integrity and sperm with low membrane lipid disorder, and also with a reduction in sperm motility kinetic parameters when compared with results obtained from the control sample, which presented the typical motility pattern of capacitated-like boar spermatozoa. Moreover, Western blot results also showed significant (P < 0.05) changes in the levels of tyrosine, serine, and threonine protein phosphorylation because of bacterial contamination, the decrease in phosphotyrosine levels of p32, a well-known marker of IVC achievement in boar sperm, being the most relevant. Indeed, after 3 hours of IVC, phosphotyrosine levels of p32 in the control sample were 3.13 ± 0.81, whereas in the tubes with 10(6) and 10(8) CFU/mL were 1.05 ± 0.20 and 0.36 ± 0.07, respectively. Therefore, the present study provides novel data regarding the effects of bacterial contamination on boar sperm, suggesting that the presence of P aeruginosa affects the fertilizing ability of boar sperm by altering its ability to accomplish IVC.

Quality and fertilizing capacity of boar spermatozoa during liquid storage in extender supplemented with different antibiotics

The aim of the study was to determine the effect of antibiotics on quality parameters and fertilizing capacity of boar sperm during liquid preservation. In the first experiment, semen was diluted in an extender containing 200 μg/mL of gentamicin as a control and diluted in a modified extenders: Ext I (contained 200 μg/mL florfenicol), Ext II (contained 200 μg/mL polymyxin B), Ext III (contained 100 μg/mL gentamicin and 100 μg/mL florfenicol) and Ext IV (contained 100 μg/mL gentamicin and 100 μg/mL polymyxin B). The semen was stored for ten days. Sperm quality was evaluated based on the motility (CASA; TM: total motility; PM: progressive motility), membrane integrity (YO-PRO-1/PI assay), mitochondrial activity (JC-1) and DNA integrity (TUNEL). The highest PM% (62.5 ± 9.6) was observed in Ext III at Day 6 of storage. The highest sperm viability and mitochondrial transmembrane potential was noticed at the end of the storage period in Ext III. Long-term storage did not induce DNA fragmentation in the extenders analyzed. In the second experiment, semen diluted in the control extender and in the extender providing the highest quality spermatozoa on Day 10 (Ext III) was used for artificial insemination (AI) of synchronized gilts. Our studies showed that the highest reproductive performance of inseminated gilts (pregnant gilts: 97.0%, litter size: 11.4 ± 1.2) occurred with Ext III semen dilution. The combination of 100 μg/mL gentamicin and 100 μg/mL florfenicol in the extender maintained sperm motility, membrane integrity and mitochondrial activity and enhanced the higher reproduction success.

Effects of different concentrations of Pseudomonas aeruginosa on boar sperm quality

Bacteriospermia in boar ejaculates is a frequent finding that compromises the sperm quality and, consequently, causes economic losses in swine industry. The present study sought to evaluate the effect of different concentrations of Pseudomonas aeruginosa on boar sperm quality over a storing period of 11 days at 15-17 ° C. Ten commercial seminal doses coming from post-pubertal and healthy boars were artificially inoculated with different infective concentrations of P. aeruginosa, ranging from 2 × 10(8) to 2 × 10(4)cfu/mL. Negative controls were non-inoculated doses. Sperm quality, assessed as sperm motility (CASA), sperm viability, acrosome integrity and pH, as well as the bacterial growth, were checked after 0, 1, 2, 4, 7, 9 and 11 days of storage at 15-17 ° C. Results obtained showed significant decreases in the percentages of total and progressive sperm motility, sperm viability and acrosome integrity in the greatest infective concentrations (2 × 10(7) and 2 × 10(8)cfu/mL), when compared to the negative control. In contrast, there was no effect on seminal pH throughout the experiment. Results indicate the presence of P. aeruginosa in boar semen, apart from being a potential source for the spread of infectious diseases and harmful impact on sows, negatively affects the longevity and fertilizing ability of boar sperm when present in high concentrations. Thus, P. aeruginosa causes deleterious effects on boar sperm quality during liquid storage at 15-17 ° C, thus strict hygienic measures must be implemented in boar studs to minimize bacterial concentration of semen doses.