Effects of Nondigestible Oligosaccharides on 'Salmonella enterica' Serovar Typhimurium and Nonpathogenic 'Escherichia coli' in the Pig Small Intestine In Vitro

An in vitro intestinal tissue model was developed for the investigation of bacterial association in the pig small intestine under different dietary regimes. In preliminary experiments, jejunal and ileal tissue was taken from Danish Land race pigs fed standard diet and inoculated with either 'Salmonella' or non pathogenic 'Escherichia coli' strains. Higher numbers of salmonellae associated with the ileal tissues, but the numbers did not reach significance. Hence, jejunal sections were inoculated with nonpathogenic 'E. coli' and ileal sections were inoculated with salmonellae in the presence of mannose or commercial non digestible oligosaccharides (NDO) at 2.5%. There was a significant decrease in 'E. coli' associated with the jejunum in the presence of mannose (P < 0.05). Furthermore, in pigs fed a diet supplemented with commercial NDO at 4% there was a significant reduction in the numbers of 'E. coli' in jejunal organ cultures of pigs fed the FOS diet (P < 0.05). There was a reduction, though not a significant one, in the association of 'Salmonella' sp. to the ileal sections of pigs fed the commercial FOS diet. The feeding of commercial GOS or its addition to organ cultures did not affect 'E. coli' or 'Salmonella' numbers.