Increasing the viscosity of the intestinal contents stimulates proliferation of enterotoxigenicEscherichia coliandBrachyspira pilosicoliin weaner pigs

Abstract

The present study was designed to evaluate the effect of increased viscosity of the intestinal digesta on proliferation of enterotoxigenicEscherichia coliand the intestinal spirochaeteBrachyspira pilosicoliin weaned pigs. Pigs were fed an experimental diet based on cooked white rice (R), which was supplemented with carboxymethylcellulose (CMC; 40 g/kg diet) to increase digesta viscosity. Thirty-six piglets weaned at 21 d of age were divided into six groups, three of which were fed R and three R+CMC. Addition of CMC increased digesta viscosity in the ileum (P=0·01), caecum (P=0·0007) and colon (P=0·0035), without increasing indices of large intestinal fermentation. Pigs fed R+CMC developed a natural infection with enterotoxigenicE. coliafter weaning and had more (P<0·0001) diarrhoea than pigs fed R. Subsequent experimental infection of two groups of pigs withB. pilosicoliresulted in more (P<0·0001) colonisation in pigs fed R+CMC than R. At this time, all pigs fed R+CMC had wetter (P<0·0001) faeces than those fed R, irrespective of whether they were infected withB. pilosicoli, but infected pigs also had an increased (P=0·025) number of days with diarrhoea post-infection irrespective of diet. In pigs fed R+CMC, it was not clear to what extent the increased viscosity associated with CMC, or the concurrent infection with enterotoxigenicE. coli, was responsible for the increased proliferation ofB. pilosicoli. In a second experiment, five pigs that were weaned onto an R diet were transferred onto R+CMC 3 weeks later. These pigs did not develop a natural infection with enterotoxigenicE. coliafter the diet change, confirming the particular susceptibility of pigs to enterotoxigenicE. coliproliferation immediately post-weaning.