The effect of bacterial contamination on the biological integrity of sperm in boars

The productive longevity of sows leads to an increase in production of marketable products. However, more than half are discarded after the first farrowing due to impaired reproductive qualities under the influence of various factors including infectious diseases. The seminal material of boars can be a source of infection for sows. There is evidence of the relationship between the influence of infectious agents on the reproductive tract of producers and on inflammatory processes in the generative organs of females, which leads to a decrease in reproduction rates. In males, contamination of the sperm-­carrying ducts by microorganisms directly affects the quality of sperm production and the function of spermatozoa, which in turn leads to the production of antibodies, reactive oxygen species and DNA fragmentation. To study the effect of bacterial contamination on the biological integrity of sperm in breeding boars, three groups of animals were formed depending on the activity of spermatozoa. For the study, ejaculates of Large White, Landrace and Duroc breeding boars (n = 46) were taken. The age of the producers ranged from 18 to 40 months; ejaculates were collected in January — December. To determine qualitative and quantitative parameters of spermatozoa, Argus CASA program (ArgusSoft, St. Petersburg, Russia) was used based on CASA technology, using single-­factor analysis methods. A comprehensive assessment of the ejaculates of boar producers showed the presence of yeast and yeast-like fungi (mold) in 44% of the studied samples, in which the total number of colony-­forming microorganisms was 4895 ± 37.5 CFU/cm³, which is 8.1 times more than in samples without contamination, and the proportion of progressive motile spermatozoa was lower by 10%. In the group with high microbial contamination (4895 CFU/cm³), activity was 1.2 times lower (p < 0.001), the proportion of abnormal spermatozoa was 1.7 times higher (p < 0.001) and the level of DNA fragmentation was 3.1 times higher (p < 0.001). Correlation analysis between microbial contamination and progressively motile spermatozoa showed a negative bilateral correlation r = –0.51 (p < 0.01) and a positive correlation with abnormal morphology r = 0.42 (p < 0.05) and DNA fragmentation r = 0.56 (p < 0.01). Reproductive indicators of boars-­producers in the group with high bacterial contamination were established: fertilizing ability was 23% lower, and the number of abortions was 2.3 times higher, and the frequency of stillbirths and mummified piglets in the litter was 3 times and 2.5 times higher, respectively.