Increasing viscosity of the intestinal contents alters small intestinal structure and intestinal growth, and stimulates proliferation of enterotoxigenic Escherichia coli in newly-weaned pigs

Sources of viscous soluble fibre, such as barley and oats, have often been included in the weaning diet of the pig to accelerate development of the la rge intestine. Inclusion of a non-fermentable, viscous compound, sodium car boxymethylcellulose (CMC), in a low-fibre weaning diet was tested to assess the influence of digesta viscosity on the gut in the absence of increased fermentation. Two CMC sources, of low and high viscosity, were added to coo ked rice-based diet at 40 g/kg total diet. A third control rice diet did no t contain any CMC. Diets were fed for 13 d following weaning at 3 weeks of age. Addition of CMC to the diet significantly increased the intestinal vis cosity of digesta within the small (P <0.001) and large (P <0.05) intestine . No simple association was found between increases in intestinal viscosity and effects on intestinal morphology and whole-body growth. The average em pty-body-weight gain and the small intestinal villus height increased with low-viscosity CMC, but decreased with the high-viscosity CMC group. The ful l large intestinal weight increased in all pigs fed CMC. Dietary CMC (both low- and high-viscosity) increased the percentage moisture of digesta and f aeces, and was associated with increased faecal shedding of enterotoxigenic haemolytic Escherichia coli. Feed ingredients in weaning diets that excess ively increase the viscosity of the intestinal digesta may be detrimental t o pig health and production.