Abstract
Simple SummaryThis 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).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.
Highlights
The evolution of contemporary swine industry is closely associated with the implementation of modern reproductive technologies which have significantly contributed to a remarkable rise in the production of high-quality protein foodstuffs [1]
Our objectives were to: (a) investigate the bacteriological profiles of extended boar semen using a molecular approach based on the matrix assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry; (b) to assess the sensitivity of isolated bacteria to antibiotics, and (c) to assess the ability of selected commercially available boar semen extenders supplemented with different antibiotics to eliminate bacteria during semen storage, and to offer protection to the sperm structural integrity and functional activity
Four varieties of the Androstar Plus boar semen extender (Minitüb, Tiefenbach, Germany) were used for the study: Androstar Plus without antibiotics served as the control (Ctrl), while the experimental groups consisted of Androstar Plus containing gentamycin exclusively (Experimental group 1; Exp 1), Androstar Plus supplemented with gentamicin, aminoglycosid and cephalosporin (Experimental group 2; Exp 2) and Androstar Plus with
Summary
The evolution of contemporary swine industry is closely associated with the implementation of modern reproductive technologies which have significantly contributed to a remarkable rise in the production of high-quality protein foodstuffs [1]. Artificial insemination (AI) has become a popular choice for an intensive pig production, since approximately 90% of sows are being fertilized artificially in the leading pork producing countries [1,2]. Amongst numerous endogenous and exogenous factors that may contribute to a decreased fertility in animal breeding, bacterial contamination of semen may be responsible for a reduced shelf life of extended semen, conception rates and litter size [2,4–6]. Contaminated water and feed, air ventilation, bedding or poor hygiene conditions of the breeding facility may lead to bacterial infestation of semen [7]
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