Submitted to: American Society of Animal Science Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: February 17, 2005
Publication Date: July 27, 2005
Citation: Wells, J., Varel, V.H. 2005. Viability of Salmonella enterica Typhimurium and Escherichia coli O157:H7 in finishing swine manure slurries with and without a urease inhibitor and a plant essential oil [abstract]. Journal of Animal Science. 83(Supplement 1):301-302. Technical Abstract: Pathogens are commonly found in animal waste and their viabilities in manures are a concern for the environment and food safety. To determine the effects of urine and feces content, and treatments with a urease inhibitor and/or an odor-reducing compound, selected strains of Salmonella enterica Typhimurium and Escherichia coli O157:H7 were inoculated into swine manure slurries. Fresh (overnight) feces were collected from pens of swine fed a finishing ration, blended with urine and manure additives, and inoculated with S. enterica Typhimurium strain 14028 (nalidixic acid-resistant) and E. coli O157:H7 strain 43895 (streptomycin-resistant). On d 0, a 1 g sample of the inoculated slurry was diluted and viable counts were determined by plating onto agar medium with either nalidixic acid or streptomycin. Viable counts were determined daily until no longer detectable. In slurries containing approximately 1:1 or 2:1 of urine and feces, the decrease in viability of Salmonella and E. coli were similar and few viable cells were found after 14 d. When the urine content of the slurry was increased to 5:1, both Salmonella and E. coli died off faster (5.7- to 6.0-fold, P < 0.01) than the 1:1 slurries and few viable cells were detectable after 2 d. When the urease inhibitor, N-(n-butyl) thiophosphoric triamide (NBPT), was added to the slurries, pathogen viability was not affected in the 1:1 manure slurry where urea content was low. However, in the 2:1 and 5:1 slurries where urea content was higher, NBPT addition prolonged the viability of Salmonella and E. coli up to 10 d (P < 0.05). Thymol addition, regardless of NBPT treatment or the urine to feces ratio, dramatically decreased (P < 0.01) pathogens and few viable counts of Salmonella or E. coli O157:H7 were observed after d 1. These experiments suggest that urea hydrolysis in swine waste may control pathogen levels and the inhibition of this biological process may promote pathogen viability unless antimicrobial compounds are also utilized.