The use of ethyl lauroyl arginate encapsulated in organic nanoparticles within boar semen extenders to control bacterial growth and preserve sperm quality during short-term storage without antibiotics

The aim of the present study was to investigate the effect of adding ethyl lauroyl arginate (ELA), encapsulated in organic nanoparticles, to a semen extender without antibiotics on sperm quality and bacterial load during short-term storage. Three ejaculates from Duroc boars were divided into four equal portions and diluted with Beltsville Thawing Solution to produce semen doses containing 3 billion spermatozoa in 80 ml. The extended semen did not include antibiotics but instead incorporated different concentrations of ELA nanoparticles into the extenders: 0 ppm, 5 ppm, 10 ppm, and 15 ppm. The semen doses were stored for 4 days, with daily evaluations of semen quality and bacterial counts conducted on days 0, 1, 2, and 3. During storage, sperm motility, viability, acrosome integrity, sperm membrane integrity, mitochondrial activity, and total bacterial count (CFU/ml, log10) were evaluated. Total sperm motility and motion parameters, including straight-line velocity (VSL, µm/sec), curvilinear velocity (VCL, µm/sec), and average path velocity (VAP, µm/sec), were assessed using a computer-assisted sperm analyzer (CASA). During the 3 days of semen preservation, the bacterial load in extended boar semen without ELA (0 ppm group) tended to be higher than in semen extended with 5 ppm ELA (3.9 vs. 3.4 CFU/ml, P = 0.096) and was significantly higher than in semen extended with 10 ppm (3.3 CFU/ml, P = 0.045) or 15 ppm ELA (3.2 CFU/ml, P = 0.010). No significant differences were observed in total sperm motility, VSL, sperm viability, or sperm membrane integrity between the 0 ppm and 5 ppm ELA groups (P > 0.05). However, total sperm motility in boar semen without ELA supplementation (69.6 ± 6.7%) was higher than in semen extended with 10 ppm (58.6 ± 6.7%, P = 0.031) or 15 ppm ELA (55.1 ± 6.7%, P = 0.006). In addition, sperm plasma membrane integrity in the 0 or 5 ppm ELA treatments was higher than in semen supplemented with either 10 ppm or 15 ppm ELA (P < 0.05). No differences in sperm acrosome integrity were found across the four groups (P > 0.05). In conclusion, our findings suggest an alternative antimicrobial agent for reducing antibiotic use in the boar artificial insemination industry. Encapsulated in organic nanoparticles at concentrations of 10 to 15 ppm, ELA effectively controlled bacterial growth during short-term storage without the need for antibiotics but negatively affected some sperm quality parameters. Therefore, using 5 ppm of ELA encapsulated in organic nanoparticles