In vitro anaerobic incubation of Salmonella enterica serotype Typhimurium and laying hen cecal bacteria in poultry feed substrates and a fructooligosaccharide prebiotic

The objective of this study was to investigate the effect of combining a prebiotic with poultry feeds on the growth of Salmonella enterica serotype Typhimurium (ST) in an in vitro cecal fermentation system. Cecal contents from three laying hens were pooled and diluted to a 1:3000 concentration in an anaerobic dilution solution. The cecal dilution was added to sterile test tubes filled with alfalfa and layer ration with and without fructooligosaccharide (FOS). Two controls containing cecal dilutions and anaerobic dilution solution were used. The samples were processed in the anaerobic hood and incubated at 37 degrees C. Samples were inoculated with Salmonella at 0 and 24h after in vitro cecal fermentation and plated at 0 and 24h after inoculation with ST. Plates were incubated for 24h and colony forming units (CFU) enumerated. The samples immediately inoculated with ST without prior cecal fermentation did not significantly lower ST counts 24h later. However, samples pre-incubated for 24h with cecal microflora prior to ST inoculation exhibited reduced ST CFU by approximately 2 logarithms, with the most dramatic decreases seen in alfalfa and layer ration combined with FOS. The addition of FOS to feed substrate diets in combination with cecal contents acted in a synergistic manner to decrease ST growth only after ST was introduced to 24h cecal incubations.