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

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.

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

“…Most of the gram-negative bacteria isolated in our study had a high-level resistance rate of antimicrobials when tested against neomycin, penicillin, lincomycin, and ceftiofur ( Table 1 ). These results are correlated with previous studies [ 13 , 31 , 34 ] reporting that several bacterial genera and species exhibit a certain degree of resistance to gentamycin and aminoglycosides (the most common antibiotics used in semen extenders) leading to a concerning assumption that none of these antibiotics was able to effectively eradicate Gram negative bacteria present in diluted semen samples.…”

“…In a study conducted by Tvrda et col. [ 13 ] in Slovakia, 12 bacterial genera and 16 bacterial species were isolated and identified in boar ejaculates immediately following semen dilution, using MALDI-TOF mass spectrometry, as follows: Proteus vulgaris, E. coli, Pseudomonas aeruginosa, Pseudomonas putida, Klebsiella pneumoniae, Aerococcus viridans, Staphylococcus aureus, Staphylococcus chromogenes, Staphylococcus simulans, Clostridium difficile, Enterococcus hirae, Bacillus cereus, Bacillus licheniformis, Bacillus subtilis, Acinetobacter iwoffii, Rothia nasimurium, and Corynebacterium spp.…”

“…Tvrda et al [ 13 ] reported that 76% of semen samples had been contaminated with relatively high variety of bacterial genera, predominantly well-known uropathogens.…”

“…In their study, Tvrda et al [ 13 ] reported that gentamycin was effective enough to eradicate gram-negative bacteria , E. coli, Klebsiella pneumoniae, Proteus vulgaris strains showed 100% sensitivity to ampicillin. We can according to Maroto Martín et al [ 12 ] Bresciani et al [ 25 ] and Gączarzewicz et al [ 28 ], who pointed out that a significant proportion of the bacteria commonly found in boars ejaculate in Europe may be resistant to gentamicin.…”

Bacteria and Boar Semen Storage: Progress and Challenges

“…Therefore, the use of antibiotics should be specific and should not be added randomly in commercial media. Specific antibiotics for semen extension and hygiene standards should preserve semen quality and reduce the indiscriminate use of antibiotics and the antibiotic resistance crisis in the pig industry [ 47 ].…”