OxyFile #423

Bactericidal effects of ozone at nonspermicidal concentrations.

Gradil C; Eaglesome MD; Stewart B; Garcia MM; Quimby F

Agriculture and Agri-Food Canada, Animal Diseases Research 
Institute, Nepean, Ontario.

Can J Vet Res, 59: 3, 1995 Jul, 183-6

Abstract

A study was conducted to assess the use of ozone (O3) to control 
pathogens or contaminants of concern to animal breeders and 
regulatory officials. In separate experiments, samples of fresh 
bovine semen and Pseudomonas aeruginosa, Escherichia coli, or 
Campylobacter fetus subsp. venerealis were diluted with 
antibiotic-free milk (10(6) sperm and 10(6) organisms/mL of 
diluted semen), exposed in the previous day to a constantly 
monitored level of 5, 10, 15, or 20 micrograms/mL of O3 for 3-5 
min. After 10 min at 30 degrees C, sperm motility was assessed and 
the samples cooled to 5 degrees C. Two and 18 h after the 
beginning of cooling, aliquots of each semen sample were evaluated 
for motility and cultured for organisms. Reductions were observed 
in P. aeruginosa and E. coli colony counts of 2 logs, and in C. 
fetus of 5 logs, after exposure for 2 h to O3 at a concentration 
of 5 micrograms/mL that had a moderate effect on sperm motility 
(reduction of 20%). Fewer than 100 colonies, i.e., a 4 logs 
reduction of all bacteria, were counted after dilution with 
ozonized-treated milk at 20 micrograms/mL of O3. However, this 
concentration of O3 reduced sperm motility by 50% 10 min after 
dilution. The results of these experiments indicate that a 
concentration and exposure time to O3 can be selected to reduce P. 
aeruginosa, E. coli, and C. fetus in contaminated bull semen 
diluted with milk while having only minimal effects on sperm 
motility.