[Microfloral study of bull seminal fluid stored at low temperatures].

Hundred twenty three samples of bull semen fluid frozen at 196 degrees C including 83 plastic ampules, 20 granules and 20 plastic straws obtained from the containers of the insemination stations of 10 farms from the Sofia district were investigated. Two hundred twelve strains were isolated and identified as: Escherichia coli--25 strains, Hafnia--16 strains, Citrobacter, Enterobacter and Proteus mirabilis--9 strains of each. The remaining Gram-negative genera and species were more rarely encountered. Gram positive bacteria: Micrococcus--19 strains, Staphylococcus aureus--17 strains, Staph. epidermidis--15 strains, Bacillus cereus--15 strains, B. subtilis--12 strains. Other representatives of Gram-positive bacteria were also found but in lower percentages. Least bacteria were observed in semen fluid frozen in plastic straws and most--in plastic ampules which were mainly used until recently for cow insemination. It was established that the same bacteria isolated by other authors from fresh sperm were encountered in semen fluid stored at minus temperatures. The conclusion is made that semen fluid stored at low temperature is contaminated with bacteria. It is only natural that these bacteria are introduced in cow genitals by insemination.