Quality of inseminating dose of boar semen and its correlation with seminal bacterial population

It is known that the bacterial contamination of the boar semen may reduce the seminal quality and to cause uterine disorders in the sow. Therefore, the understanding of the bacterial contamination of the semen and its outcome on sperm cell function is necessary to obtain high fertility rates. Thus, the objective was to identify the main bacteria present in the fresh and cooled boar semen and to correlate them with the seminal quality parameters. Twenty six ejaculates were collected from different boars and, immediately, samples were sending for microbiological analysis for bacterial isolation. Thereafter, the ejaculates were diluted in non-supplemented antibiotic media to obtain inseminating doses of 3x109 cells/mL, which were stored at 15 o C for 72 hours. Another microbiological analysis was performed 72 hours later. Each microorganism identified was correlated with each sperm quality parameters by Pearson´s correlation test. It was observed that the UFC/mL values obtained from the cooled semen were numerically greater than those from fresh semen. Sthaphylococcus spp. (77% of ejaculates) and Proteus mirabillis (77%), Burkholderia cepacia (35%) and Morganella morganii (31%) were the most frequent bacteria found in fresh semen. In the cooled semen, there was an increase in P. mirabilis (96% of ejaculates) and reduction of M. morganii (31%) and Staphylococcus spp. (27%). In general, bacterial contamination has negative correlation with seminal parameters. The most harmful bacteria to affect the semen quality was P. mirabillis that showed negative correlation with spermatic motility and positive correlation with total morphological changes, sperm viability and percentage of whole acrosomes. By other hand, B. cepacia and M. morganii seem to be beneficial effect on the quality of the semen, since they affected positively the acrosome integrity and velocity of the fresh semen and sperm viability in the cooled semen. In conclusion, bacterial population affect the quality of inseminating doses stored at 15 o C for 72 hours. P. mirabillis is the most harmful bacterial for the boar ejaculates while B. cepacia and M. morganii seem to bring positive effects on the semen quality.