Intestinal degradation in pigs of rye dietary fibre with different structural characteristics

in order to investigate the effects of dietary fibre (DF) characteristics o n carbohydrate degradation and the metabolism in the large intestine, pigs were fed on four rye-bread diets (based on whole rye, pericarp/testa, aleur one or endosperm) with differences in characteristics and amount of DF. The degradability-of DF in the large intestine varied greatly between diets. T he pericarp/testa DF was hardly degraded in the large intestine, whereas en dosperm DF was extensively and rapidly degraded in the caecum. Caecal degra dation of aleurone DF was also limited, leaving more material to be degrade d in the colon. The undegradable pericarp/testa DF was characterized by hig h contents of lignin, cellulose, ferulic acids and highly substituted arabi noxylans (the major DF component in rye). Ingestion of this diet resulted i n increased faecal bulk and reduced transit time, but with low colonic pH a nd the lowest concentrations of short-chain fatty acids (SCFA). The aleuron e diet, on the other hand, led to a fermentation pattern which may be consi dered more optimal, with lower colonic pH and higher concentrations of SCFA , in particular butyric acid. Despite the large differences in carbohydrate fermentation only minor significant effects on the presence of protein deg radation products and on histological measurements (height and diameter of colonic crypts and thickness of the muscularis externa) were observed.