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

Area of Science:

• Reproductive Biology
• Microbiology
• Animal Science

Background:

• Antibiotics are routinely added to boar semen extenders for artificial insemination (AI) per national and international guidelines.
• This non-therapeutic use of antibiotics contributes to the development of antibiotic resistance.
• Colloid centrifugation has demonstrated potential in reducing bacterial load in boar semen.

Purpose of the Study:

• To investigate the efficacy of low-density colloid centrifugation in removing bacteria from boar ejaculates without compromising sperm quality.
• To assess if this method can eliminate bacterial contamination without antibiotic use.
• To evaluate the impact of centrifugation on sperm parameters during storage.

Main Methods:

• Boar ejaculates were extended in antibiotic-free Beltsville Thawing Solution.
• Single Layer Centrifugation (SLC) was performed using a low-density modified Porcicoll (S) and a modified technique with an inner tube (M).
• Bacterial quantification and identification were conducted using standard microbiological methods; sperm quality was assessed daily.

Main Results:

• Centrifugation significantly reduced bacterial counts (P < 0.01), with S and M samples showing mean counts of 30 ± 22 and 33 ± 15 CFU/mL, respectively, compared to 259 ± 216 CFU/mL in controls.
• Three (M) and five (S) samples were rendered bacteria-free.
• Sperm velocity and linearity were higher in S and M samples, with no significant differences in viability, capacitation, or acrosome status during storage.

Conclusions:

• Low-density colloid centrifugation effectively removes or reduces bacterial contamination in boar ejaculates without the need for antibiotics.
• Strict adherence to hygiene during semen collection can achieve bacteria-free ejaculates.
• This method presents a viable antibiotic-free alternative for preparing semen doses for artificial insemination.