CONFIRMATION OF THE ROLE OF RAPIDLY FERMENTABLE CARBOHYDRATES IN THE EXPRESSION OF SWINE-DYSENTERY IN PIGS AFTER EXPERIMENTAL-INFECTION

Two experiments were conducted to test the hypothesis that soluble non -starch polysaccharides (NSP) and resistant starch (RS) cause swine dy sentery (SD) in pigs experimentally infected with the spirochete Serpu lina hyodysenteriae, In Experiment I, a source of soluble NSP (guar gu m; GG), insoluble NSP (oat chaff; OC), resistant starch (retrograde co rnstarch; RS) or a combination of GG and RS (GG + RS) was added to a d iet containing cooked white rice (R), soybean meal (SBM) and animal pr otein (meat and bone meal, bloodmeal, fishmeal), A diet containing onl y cooked white rice, SBM and the sources of animal protein (AP) was al so fed. In Experiment 2, three rice-based diets containing different l evels of RS were fed to pigs. In Experiment 1, the pH of digesta in th e cecum, proximal colon and distal colon of pigs fed diets R-GG, R-RS and R-GG + RS was lower (P < 0.001), and volatile fatty acid concentra tion higher (P < 0.001), than in pigs fed diets R-OC and R-AP. Rigs fe d diets with RS and GG + RS had greater (P < 0.05) concentrations of A TP in the large intestine than pigs fed other diets, There were no sig nificant differences in any fermentation indices measured in Experimen t 2. In Experiment I, pigs fed diets R-GG, R-RS and R-GG + RS were col onized with S, hyodysenteriae after experimental infection. However, o nly pigs consuming diets R-GG (4 of 5) and R-GG + RS (5 of 5) showed c linical signs of SD. Spirochetes were isolated from the feces of all p igs fed diets containing RS in Experiment 2. However, and in contrast to Experiment 1, 80-100% of pigs infected with S. hyodysenteriae displ ayed clinical signs of SD. These data confirm the role of fermentable carbohydrate in the pathogenesis of SD.