Influence of bacterial products on the motility of stallion spermatozoa.

The research studied the impact of bacterial products on the mobility of stallion sperm, finding a significant reduction in mobility when semen was mixed with filtrates derived from various types of bacteria.

Methodology

• The researchers prepared sterile ‘filtrates’ from eight equine bacterial isolates – Klebsiella pneumoniae (genitalium), Proteus mirabilis, Pseudomonas aeruginosa, Escherichia coli, Streptococcus zooepidemicus, Streptococcus equisimilis, Actinobacillus equuli, and Corynebacterium equi.
• Each of these filtrates was mixed individually with extended stallion semen, with filtrate densities ranging from 0.5 x 10(6) to 4 x 10(6) cells/ml to replicate different bacterial populations.
• The pH value of each filtrate was also recorded.
• Ten semen samples were drawn from five clinically normal stallions and were maintained at a constant temperature of 25 degrees Celsius throughout the experiment.

Observations and Findings

• The researchers tracked the percentage of motile (moving) spermatozoa in each mixture at 30-minute intervals.
• The monitoring continued until the percentage of motile spermatozoa fell to 10% or less for two consecutive observations.
• The major drop in sperm motility compared to the control sample (the semen not mixed with bacterial filtrates) occurred even before the first observation.
• After this initial decrease, the rate of decline in motility matched that of the control sample.

Statistical Significance

• All differences detected between filtrate and control samples in terms of motile sperm cells were statistically significant, with a P-value of less than 0.01. A P-value of less than 0.05 is commonly considered statistically significant in scientific studies, indicating that the results are unlike to have occurred by chance.