[Effect of long-term freezing preservation on the level of bacterial contamination of the sperm]. / Vliv dlouhodobé konzervace zmrazováním na hladinu bakteriální kontaminace spermatu

Fourty-five ejaculates of breeding bulls were examined at a breeding station in order to study the contamination level of sperm after ejaculation, after thinning, after finished equilibration, after freezing, and after three months after placement in liquid nitrogen at -- 196 degrees C. The amount of germs in sperm was found to increase rapidly in the course of examination and thinning at laboratory temperature. The average number of 4,149 germs increased to 9,729. During equilibration the number of germs dropped to 3,670, after freezing it decreased to 2,442, and after three months of storage in liquid nitrogen the contamination level was 901 germs. All values were converted to the volume of the insemination dose of 0.2 ml. Incubation at 37 degrees C lasted 48 hours. All differences were statistically significant. The freezing of thinned sperm significantly reduced the level of microflora.