A total of sixty surgically castrated male pigs (Large White × Landrace) weighing 31·2 (sd 4·3) kg were used in a randomised block experiment to examine the effect of added dietary inulin (0, 20, 40 and 80 g/kg) on the occurrence of swine dysentery (SD) and on fermentation characteristics in the large intestine after experimental challenge with the causative spirochaete Brachyspira hyodysenteriae. The pigs were allowed to adapt to the diets for 2 weeks before each pig was challenged orally four times with a broth culture containing B. hyodysenteriae on consecutive days. Increasing dietary levels of inulin linearly (P = 0·001) reduced the risk of pigs developing SD; however, eight out of fifteen pigs fed the diet with 80 g/kg inulin still developed the disease. The pH values in the caecum (P = 0·072) tended to decrease, and in the upper colon, the pH values did decrease (P = 0·047) linearly with increasing inulin levels in the diets, most probably due to a linear increase in the concentration of total volatile fatty acids in the caecum (P = 0·018), upper colon (P = 0·001) and lower colon (P = 0·013). In addition, there was a linear reduction in the proportion of the branched-chain fatty acids isobutyric acid and isovaleric acid in the caecum (P = 0·015 and 0·026) and upper colon (P = 0·011 and 0·013) with increasing levels of dietary inulin. In conclusion, the present study showed that a diet supplemented with a high level of inulin (80 g/kg) but not lower levels reduced the risk of pigs developing SD, possibly acting through a modification of the microbial fermentation patterns in the large intestine.

The purpose of the present study was to evaluate the effect of fermented liquid food (FLF) and the addition of lactic acid to a diet based on wheat and barley on the development of swine dysentery in pigs experimentally infected with a Danish field isolate of Brachyspira hyodysenteriae. Furthermore, to confirm if low non-starch polysaccharide (NSP)-containing diets reduce swine dysentery the effect of different dietary levels of NSP and resistant starch (RS) was evaluated. These diets were based on cooked rice and animal protein, cooked rice and potato starch, cooked rice and wheat bran, or cooked rice and sugar-beet pulp. The experiment was designed as a randomized-block trial and was performed in triplicate including a total of 192 pigs. After feeding the diets for 2 weeks, six pigs in each group were challenged orally with B. hyodysenteriae and observed for another 4 weeks. After challenge, swine dysentery was observed in all feeding groups. The incidence of disease varied between 94% (rice/wheat bran) and 44% (FLF). The effect of diet on faecal shedding of B. hyodysenteriae was statistically significant (P < 0·05). Feeding a diet based on cooked rice with a low content of NSP and RS, did not prevent the development of swine dysentery upon experimental challenge, and increasing the level of NSP or RS did not result in a higher incidence of disease or faecal shedding of B. hyodysenteriae. The incidence of swine dysentery in the FLF group was significantly lower (P < 0·05) compared with all other feeding groups, except for the lactic acid group. In conclusion, a low level of NSP or RS in the diet did not prevent the development of swine dysentery. Furthermore, the lowest incidence of disease was observed in the FLF group, even though this diet has a high content of NSP. The addition of organic acids to the food was not able to reduce infection with B. hyodysenteriae.

Diets containing soluble NSP (sNSP) and resistant starch (RS) increase hindgut fermentation in pigs, which in turn increases the incidence of swine dysentery (SD) after infection with the intestinal spirochaete Brachyspira hyodysenteriae. In the present study pigs were fed diets based on either wheat or sorghum, fed either raw or treated by extrusion, and/or with the addition of dietary enzymes to reduce RS and/or sNSP content. The aim was to determine the effects of these treatments on pig performance, large intestinal fermentation and expression of SD. Weaned pigs (n 132) were fed experimental diets for 4 weeks, when half the pigs in each treatment group were euthanased and samples collected to assess the influence of the diet on hindgut fermentation. The remaining pigs then were infected with B. hyodysenteriae, and monitored for development of SD. In general, compared with pigs fed raw wheat, fermentation in all parts of the large intestine was reduced either by feeding raw sorghum-based diets, or by feeding diets that were extruded. The addition of enzymes that degrade RS or sNSP reduced fermentation only in the distal parts of the large intestine. The incidence of SD was lower in pigs fed sorghum-based diets, and some of the extruded diets, but none of the dietary treatments offered full protection against SD. Multiple regression analysis of the results from all three experiments showed that colonisation by spirochaetes was highly related to dietary sNSP concentrations, whilst development of SD was similarly influenced by RS content of the diet.