Submitted to: International Symposium on the Epidemiology and Control of Foodborne Pathogens in Pork
Publication Type: Proceedings
Publication Acceptance Date: 6/17/2009
Publication Date: 9/30/2009
Citation: Bahnson, P.B., Smith, D.J., Anderson, R.C., Borys, K.D. 2009. Chlorate Concentration in the Jejunum and Cecum in Growing Pigs when Supplemented in Drinking Water. In: Proceedings of International Symposium on the Epidemiology and Control of Foodborne Pathogens in Pork, September 30-2 October 2009, Quebec, Ontario, Canada. Interpretive Summary: Each year there are thousands of cases of food poisoning in the United States because of the consumption of Salmonella contaminated meat products. Recent research has shown that administration of chlorate salts to food animals will either eliminate Salmonella or will greatly reduce their concentrations in the gastrointestinal tracts of food animals. Unfortunately the relationship between the dose of chlorate in live animals and its effectiveness is not well known. Therefore, we conducted this study to determine the concentrations of chlorate in the small and large intestines of growing swine after treatment with 3 doses of chlorate. We picked these tissues because they are typical of tissues in which Salmonella colonize and our goal was to learn what oral doses of chlorate are necessary to deliver effective quantities of chlorate to the large intestine. What we found was surprising. Even though chlorate has been shown by several studies to be effective at reducing quantities of Salmonella in large intestines of swine, little chlorate was present in the lower gastrointestinal tract. We believe that chlorate is removed from the GI tract by absorption and also by bacterial metabolism and still do not understand why it is so effective against Salmonella that inhabit the lower intestinal tract.
Technical Abstract: Prior research has demonstrated that oral administration of chlorate and nitrate results in reduced risk and / or concentration of Salmonella enterica fecal shedding of infected pigs, poultry and ruminants. The effect of chlorate is concentration dependent in vitro, but the concentrations of chlorate in the GI tract have not been measured in vivo during treatment, and consequently the optimal dose of chlorate is poorly defined. We administered three dosages of chlorate (0, 40 and 120 mg/kg/day) and nitrate (0, 4 and 8 mg/kg/day) to 18 growing pigs using a 3 x 3 factorial study design. After 1 or 5 days of treatment (9 pigs at each duration) subjects were humanely sacrificed to allow collection of jejunal and cecal content samples. The concentrations of chlorate and nitrate were designed to deliver daily doses at and above levels associated with suppressed Salmonella shedding in a prior study in our lab. Chlorate in GI samples was meaured using LC-MS-MS and nitrate was measured using ion chromatographic methods. Chlorate concentration was higher in jejunum with 120 mg / kg /day dose of chlorate (54 ppm) than with 40 mg / kg / day (17 ppm) or control (0.1 ppm).Chlorate concentration was not dependent on duration of treatment or nitrate dose. Nitrate concentration varied from 1-11 ppm, but was not reliably predicted by any factors studied. The low concentration of chlorate found in the lower GI tract (cecum and colon) are in apparent conflict with reported Salmonella suppression in pigs dosed a similar dose levels. It is possible that low chlorate concentration is more effective in vivo than expected based on in vitro work, or that higher doses may be necessary to achieve optimum effect in vivo.