Addition of pearl barley to a rice-based diet for newly weaned piglets increases the viscosity of the intestinal contents, reduces starch digestibility and exacerbates post-weaning colibacillosis

The purposes of the present study were to investigate the effects of feeding a cereal grain containing NSP on body growth and the intestinal microenvironment of recently weaned pigs, and to examine resultant associations with pathogenic Escherichia coli in the intestinal tract. In Expt 1, pearl barley, a grain rich in soluble NSP, was incorporated (250, 500 or 750 g/kg diet) into a low-fibre control diet based on cooked white rice and fed for 7-10 d following weaning. Consumption of pearl barley did not significantly alter piglet live-weight gain compared with the control cooked rice diet, but it accelerated large intestinal growth and fermentation, decreased ileal starch digestibility and increased intestinal viscosity. Expt 2 was conducted to determine whether these differences would favour proliferation of enterotoxigenic E. coli, the bacterium causing post-weaning colibacillosis (PWC). Three groups of pigs were weaned onto diets based on cooked white rice, rice with 500 pearl barley/kg, or rice with 500 g pearl barley/kg supplemented with exogenous enzymes (Porzyme(TM) 100; Danisco, Marlborough, Wilts., UK). Pigs were inoculated orally with haemolytic E. coli serovar O8;K87;K88 after weaning. Animals eating the pearl barley had increased viscosity of the intestinal contents, greater intestinal colonisation with the E. coli strain and more diarrhoea than pigs fed the rice-only diet. The enzymes did not reduce viscosity or protect from PWC. The results suggest that pearl barley alters the intestinal microenvironment and predisposes to PWC, whilst a low-viscosity, highly digestible diet based on cooked white rice is protective.