Reduction of Salmonella Typhimurium in experimentally challenged broilers by nitrate adaptation and chlorate supplementation in drinking water.
ABSTRACT The effects of two feed supplements on Salmonella Typhimurium in the ceca of market-age broilers were determined. Broilers orally challenged 6 days before slaughter with a novobiocin- and nalidixic acid-resistant strain of Salmonella Typhimurium were divided into one of four groups (20 birds each). The first group (the control group) received no treatment, the second group received sodium nitrate (SN) treatment (574 mg of NaNO3 per kg of feed), the third group received experimental chlorate product (ECP) treatment (15 mM NaClO3 equivalents), and the fourth group received ECP treatment in combination with SN treatment. The SN treatment was administered via feed for 5 days immediately before slaughter, and ECP was provided via ad libitum access to drinking water for the last 2 days before slaughter. Cecal contents were subjected to bacterial analysis. Significant (P < 0.05) Salmonella Typhimurium reductions (ca. 2 log units) relative to levels for untreated control broilers were observed for broilers receiving ECP in combination with SN. The ECP-only treatment resulted in significant (P < 0.05) reductions (ca. 0.8 log) of Salmonella Typhimurium in trial 2. We hypothesize that increasing Salmonella Typhimurium nitrate reductase activity resulted in increased enzymatic reduction of chlorate to chlorite, with a concomitant decrease in cecal Salmonella Typhimurium levels. On the basis of these results, preadaptation with SN followed by ECP supplementation immediately preharvest could be a potential strategy for the reduction of Salmonella Typhimurium in broilers.
SourceAvailable from: Jamie BartramEdited by Al Dufour, Jamie Bartram, Robert Bos and Victor Gannon, 01/2012; IWA Publishing.
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ABSTRACT: Eating inappropriately prepared poultry meat is a major cause of foodborne salmonellosis. Our objectives were to determine the efficacy of feed and water additives (other than competitive exclusion and antimicrobials) on reducing Salmonella prevalence or concentration in broiler chickens using systematic review-meta-analysis and to explore sources of heterogeneity found in the meta-analysis through meta-regression. Six electronic databases were searched (Current Contents (1999-2009), Agricola (1924-2009), MEDLINE (1860-2009), Scopus (1960-2009), Centre for Agricultural Bioscience (CAB) (1913-2009), and CAB Global Health (1971-2009)), five topic experts were contacted, and the bibliographies of review articles and a topic-relevant textbook were manually searched to identify all relevant research. Study inclusion criteria comprised: English-language primary research investigating the effects of feed and water additives on the Salmonella prevalence or concentration in broiler chickens. Data extraction and study methodological assessment were conducted by two reviewers independently using pretested forms. Seventy challenge studies (n=910 unique treatment-control comparisons), seven controlled studies (n=154), and one quasi-experiment (n=1) met the inclusion criteria. Compared to an assumed control group prevalence of 44 of 1000 broilers, random-effects meta-analysis indicated that the Salmonella cecal colonization in groups with prebiotics (fructooligosaccharide, lactose, whey, dried milk, lactulose, lactosucrose, sucrose, maltose, mannanoligosaccharide) added to feed or water was 15 out of 1000 broilers; with lactose added to feed or water it was 10 out of 1000 broilers; with experimental chlorate product (ECP) added to feed or water it was 21 out of 1000. For ECP the concentration of Salmonella in the ceca was decreased by 0.61 log(10)cfu/g in the treated group compared to the control group. Significant heterogeneity (Cochran's Q-statistic p≤0.10) was observed among studies examining all organic acids (controlled or challenge experiments), butyric acid, formic acid, a formic/propionic acid mixture, fermented liquid feed, and D-mannose. Meta-regressions were conducted to examine the source of heterogeneity among studies. For prevalence outcomes, 36% and 60% of the total variance was within and between studies, respectively. For concentration outcomes, 39% and 33% of the total variance was within and between studies, respectively. Inadequate blinding and randomization was common, and no studies undergoing meta-analysis or meta-regression were conducted on a commercial farm. The strength of evidence of the effect of these additives was very low. Studies conducted under commercial conditions are needed to understand the potential benefit of these interventions for the poultry industry and to improve the strength of evidence of the effectiveness of these additives.Preventive Veterinary Medicine 08/2012; 106(3-4):197-213. DOI:10.1016/j.prevetmed.2012.07.007 · 2.51 Impact Factor