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The aim of this study was to develop a Salmonella Typhimurium (ST) challenge model in weaned pigs suitable to evaluate effects of water and feed interventions on fecal shedding and growth performance. Two studies were performed. In Exp. 1 weaned pigs were fed either a standard diet (CON) or a diet with a high buffer capacity (HB) and challenged for either 3 or 7 consecutive days in a Latin square design with 4 x 8 individually housed pigs. In Exp. 2, the CON 7-d challenge method was chosen for further model development and validation. Thirty-two individually housed weaned pigs were divided over 4 treatments: a nonchallenged control group (NCON), a challenged positive control group (PCON), a challenged intervention group with acidified water (WATER), and a challenged intervention group with acidified feed (FEED). Pigs were orally challenged once daily on d 7 to 9 or d 7 to 13 after weaning (d 0) with 1 x109 cfu ST. From d 0 to 28, rectal temperature and occurrence of diarrhea were recorded daily, and BW and feed intake were measured weekly. Fecal samples were collected on d 0, 2, 7, 9, 13, 16, 20, 23, and 27 in Exp. 1 and d 0, 2, 7, 8, 9, 13, 15, and 27 in Exp. 2 for Salmonella quantification. The results of both experiments showed quantifiable fecal Salmonella shedding (average peak shedding of approximately 3.5 log10 and 5.5 log10 cfu/g, respectively), accompanied by a transient 0.5°C increase in rectal temperature and an increase in occurrence of diarrhea. In Exp. 2 during the week of challenge (i.e., d 7 to 14), a reduction in growth performance (ADG: -157 to 200 g/d and G:F: -0.22 to 0.25 g/d; P < 0.01) in PCON and FEED was observed compared to NCON, with WATER showing an intermediate response. The WATER treatment also showed a numerically lower peak shedding (difference of -1.3 to 1.4 log10 cfu/g) compared to PCON and FEED. To conclude, we repeatedly infected weaned pigs successfully with 1 x 109 cfu of ST for 7 consecutive days, resulting in detectable and quantifiable fecal Salmonella shedding. This ST challenge model may be suitable for evaluation of effects of water and feed interventions on peak fecal shedding and growth performance. [ABSTRACT FROM AUTHOR]

Salmonella enterica serovar Enteritidis is one of the leading causes of food-borne salmonellosis in humans. Poultry is the single largest reservoir, and the consumption of incorrectly processed chicken meat and egg products is the major source of infection. Since 2006, the use of antibiotics as growth promoters has been banned in the European Union, and the dietary inclusion of β-galactomannans (βGM) has become a promising strategy to control and prevent intestinal infections. The aim of this study was to investigate the effect of various βGM-rich products on intestinal morphology in chickens challenged with Salmonella Enteritidis. To assess this effect, a total of 280 male Ross 308 chickens were studied (40 animals per treatment housed in 5 cages). There were 7 treatments, including controls: uninoculated birds fed the basal diet (negative control) and inoculated birds fed the basal diet (positive control) or the basal diet supplemented with Salmosan (1 g/kg), Duraió gum (1 g/kg), Cassia gum (1 g/kg), the cell walls of Saccharomyces cerevisiae (0.5 g/kg), or the antibiotic colistine (0.8 g/kg). The birds were fed these diets from the d 1 to 23, except the animals in the colistine group, which were fed the diet containing the antibiotic only from d 5 to 11. The inoculated animals were orally infected on d 7 with 108 cfu of Salmonella Enteritidis. Bird performance per replicate was determined for the whole study period (23 d), and the distal ileum and cecal tonsil of 5 animals per treatment (1 animal per replicate) were observed at different magnification levels (scanning electron, light, and laser confocal microscopy). In the images corresponding to the treatments containing βGM we observed more mucus, an effect that can be associated with the observation of more goblet cells. Moreover, the images also show fewer M cells, which are characteristic of infected animals. Regarding the morphometric parameters, the animals that received Duraió and Cassia gums show greater (P = 0.001 and P = 0.016, respectively) villus length compared with the animals in the positive control, thus indicating the capacity of these products to increase epithelial surface area. However, no effect (P > 0.05) on microvillus dimensions was detected. In conclusion, the results obtained indicating the beneficial effects of these βGM on intestinal morphology give more evidence of the positive effects of these supplements in poultry nutrition. [ABSTRACT FROM AUTHOR]

Pigs (n = 88) weaned at 19 ± 2 d of age were used in a 14-d study to evaluate the effects of water-delivered direct-fed microbials (DFM) or organic acids on growth, immune status, Salmonella infection and shedding, and intestinal microbial populations after intranasal inoculation of Salmonella Typhimurium (1010 cfu/pig). Pigs were challenged with Salmonella 6 d after commencement of water treatments. Treatments were 1) control diet; 2) control diet + DFM (Enterococcus faecium, Bacillus subtilis, and Bacillus licheniformis) in drinking water at 109 cfu/L for each strain of bacteria; 3) control diet + an organic acid-based blend (predominantly propionic, acetic, and benzoic acid) in drinking water at 2.58 mL/L; and 4) control diet + 55 mg/kg of carbadox. Serum samples were taken on d 6, 8, 10, and 14 for determination of tumor necrosis factor α (TNFα) concentrations. Fecal samples were taken on d 0, 5, 7, and 11 for determination of Salmonella shedding and enumeration of coliforms. Pigs were euthanized on d 6, 8, 10, and 14. Intestinal and cecal tissue and digesta and mesenteric lymph nodes were sampled and analyzed for Salmonella. Duodenal, jejunal, and ileal mucosal scrapings were sampled for measurement of mucosal TNFα concentrations. Water delivery of DFM prevented a decline in ADG on d 2 to 6 postchallenge compared with the negative control (P < 0.05). Coliform counts tended to be greater (P = 0.09) in the cecum of the DFM treatment group on d 2 postinfection compared with the negative control and acid treatment groups. However, Salmonella prevalence in the feces, gastrointestinal tract, or lymph nodes was not affected by water delivery of acids or DFM. Serum and mucosal TNFα concentrations were not affected by treatment throughout the study with the exception of ileal concentrations on d 4 postchallenge, which were greater in the negative control group compared with all other treatments (P < 0.05). The in-feed antibiotic was the only treatment that reduced Salmonella prevalence and this was localized to the cecum on d 8 postinfection. In conclusion, the DFM and organic acid treatments used in this study offered little or no benefits to pigs infected with Salmonella and should not be considered under the constraints of this study as viable alternatives to in-feed antibiotics in a pathogen challenge situation. [ABSTRACT FROM AUTHOR]

Discusses the abstract of the study 'Real-time monitoring of Salmonella in swine: Specificity and sensitivity of bacterial detection through the gastrointestinal tracts of juvenile and market weight pigs,' presented at the American Society of Animal Science's Southern Section conference on January 31-February 4, 2003, in Mobile, Alabama.