Microbial quality of equine frozen semen.

The research study focuses on the microbial quality of equine frozen semen, highlighting the importance of monitoring bacterial contamination in the semen samples stored over a long duration in liquid nitrogen. The study emphasizes the significance of such surveillance to prevent the potential transmission of diseases in the Artificial Insemination (AI) process.

Study Approach & Methodology

• The researchers conducted a qualitative and quantitative analysis to evaluate bacterial contamination in equine frozen semen samples that were stored in liquid nitrogen for a duration between 3 to 17 years.
• The semen samples under observation, both formulated in Italy and another European country, were cryopreserved in sealed plastic straws.
• The study examined a total of one hundred and ten such straws for any signs of pathogenic or non-pathogenic bacteria, aerobic or anaerobic organisms, as well as moulds and yeasts.

Results and Observations

• The Total Microbial Charge (the sum of all the different types of microbes present) showed a significant variation, with an average count of about 1.4 x 10^5 Colony Forming Units (CFU)/ml.
• The common microbial agents detected were fungi (17.5%), Enterobacter-coccus spp. (15%), Pseudomonas spp. (6.25%), Stenothophomonas maltophila (6.25%), and the anaerobic bacteria, Propionibacterium granulosum (7.5%) and Clostridium spp. (3.75%). In addition, 3.75% were observed as unidentified Gram-negative rod and cocci.
• However, certain organisms such as Streptococcus spp., Staph. aureus, E. coli, Th. equigenitalis, and Mycoplasma spp. were not detected in any samples.
• The most abundantly represented species were Enterobacter-coccus spp. (1.1 x 10^5 CFU/ml), St. maltophila (8 x 10^4 CFU/ml) and Pr. granulosum (7 x 10^4 CFU/ml), whereas yeast and moulds were found to be less prevalent (4.7 x 10^4 and 3.4 x 10^4 CFU/ml respectively).

Significance of the Study

• Understanding the microbial quality of equine frozen semen is critical to preventing the transmission of venereal diseases and to improve the overall quality of cryopreserved germplasm.
• The findings provide an important basis for the use of bacteriological surveillance in managing equine frozen semen, and thereby enhancing the success rate of artificial insemination and reducing health risks.