It is known that, non-starch polysaccharides (NSP) modify intestinal microbiota by changing digesta viscosity, transit time, and substrate availability for bacterial hindgut fermentation. Some NSP promote the intestinal abundance of pathogenic Escherichia coli in pigs. However, their impact on pathogenic clostridia in the porcine intestinal tract is unknown. The present study aimed to determine the abundance of pathogens belonging to Clostridium clusters I and XI in faeces of growing pigs fed four semi-purified diets containing 5% of purified NSP differing in viscosity and fermentability [low-fermentable low-viscous cellulose (CEL); low-fermentable high-viscous carboxymethylcellulose (CMC); high-fermentable low-viscous oat β-glucan (LG); and high-fermentable high-viscous oat β-glucan (HG)]. The NSP concentrates were included at levels of 5.20, 6.25, 8.95 and 9.25% for CEL, CMC, LG and HG, respectively, to reach 5% of the pure NSP in the diet. Eight crossbred pigs (22Kg, 7-8 weeks of age) were assigned to one of four diets in a double 4x4 Latin Square design resulting in 8 observations per diet. The four experimental periods consisted of a 10 d adaptation period followed by 3 d collection faeces. For quantification of clostridial pathogens, toxin genes were determined using quantitative PCR.
Clostridium perfringens α-toxin was detected in faeces of pigs fed low-fermentable cellulose and carboxymethylcellulose diets but was generally below detection limit for the two high-fermentable oat β-glucans. Clostridium botulinum toxin C2 was higher (P<0.05) by 0.7 to 0.9 log units in faeces of pigs fed the low-fermentable low-viscous cellulose diet than of pigs fed the other three diets. Clostridium difficile toxin B and Clostridium sordellii phospholipase C were not detected in pig faeces indicating that pigs were not colonized by these clostridial species belonging to Clostridium cluster XI.
In conclusion, the present results indicate that high-fermentable NSP, i.e. LG and HG, may lower the faecal abundance of C. perfringens and to get her with low-fermentable high-viscous CMC that of C. botulinum in growing pigs when compared to low-fermentable low-viscous CEL. Overall, the potential of a NSP to support or reduce clostridial enteric pathogens appeared not to solely depend on direct effects of viscosity and fermentability of the NSP but may be also related to their structural characteristics and indirect effects of NSP on nutrient flow in the intestinal tract of pigs.
Metzler-Zebeli, B.U., Lange, J.C., Zijlstra, R.T. and Gänzle, M.G. (2013). Dietary non-starchpolysaccharides alter the abundance of pathogenic clostridia in pigs. Livestock Science 152; 31–35. http://dx.doi.org/10.1016/j.livsci.2012.12.004