Effects of semen collection practices on the bacterial load of stallion semen

The first aim of the present study was to identify a possible relationship of bacterial load in the semen with the frequency of mounts and the influence on quality parameters. This study is, as far as we know, the first report evaluating the changing of the disposable inner liner after repeated unsuccessful mounts to the dummy and its relation to the resulting bacterial load in the obtained ejaculates. Referring to the aims of the study it could be recorded that the number of mounts is not positively correlated with the bacterial load found in the semen but with the number of contacts with the disposable inner liner. A replacement of the used disposable inner liner after several mounts leads to a decline of CFU. Even if bacterial contamination did not significantly affect the quality of semen, the number of mounts and the bacterial load were negatively correlated to the quality parameters. Bacterial flora was found in every tested ejaculate due to the fact that semen collection was carried out with a closed AV. Besides the normal commensals facultative pathogens could be found. Two facultative pathogenic species (Klebsiella pneumoniae and Streptococcus equi subspecies zooepidemicus) were found in the semen. Even if Klebsiella pneumoniae and Escherichia coli did not have any significant influence on the quality sperm parameters, AM/PM-integrity decreased when Streptococcus equi subspecies zooepidemicus was found. Whereas an increasing number of contacts to the same disposable inner liner show a positive correlation to the number of CFU, it could be noted that the number of CFU had an influence on the sperm parameters, demonstrated by the 3rd mount that showed the poorest quality. The number of CFU was negatively correlated to the values of motility, progressive motility and AM/PM-intact spermatozoa. This could be verified by replacing the disposable inner liner after the 3rd mount with a new one so that an impressive and significant decline of CFUs within the 4th mount could be reported. Organisms commonly found in semen could also represent potential pathogens and could be transmitted from the semen to the mare and cause inflammation. Most of the pathogens were not apparent in the stallion. The present study shows, that changing the disposable inner liner after a certain number of mounts can reduce bacterial load in the semen and avoid a transmission of potential pathogenic bacteria via AI to the mare. This simple sanitary procedure could help improve hygienic standards and decrease the possibility of transmission and spread of diseases. The second objective of this study was to investigate the effects of pre-coital sexual stimulation on the quality and quantity of semen. It could be verified, that the frequency of manipulated blind mounts with lateral deviation of the penis by the collecting technician had no significant influence on quantity parameters like volume, sperm concentration and total sperm count. Instead a decrease of the semen quality could be detected. Summarizing both studies it could be verified that there is a great importance in the preparation of the stallion before the mount in order to obtain high-quality semen with the first mount.