Coarse brown rice increases fecal and large bowel short-chain fatty acids and starch but lowers calcium in the large bowel of pigs

Young male pigs were fed a diet formulated from human foods including eithe r boiled white rice plus rice bran or heat-stabilized brown rice at equival ent levels of fiber for 3 wk, Stool and starch excretion were low in pigs f ed white rice during the first 2 wk of the experiment. In pigs fed brown ri ce, their excretion was high during wk 1 but declined in wk 2 while short-c hain fatty acid (SCFA) excretion was higher at both times. Large bowel dige sta mass, measured during wk 3, was higher in pigs fed brown rice but only in the proximal colon. Large bowel and fecal starch concentrations were hig her in pigs fed brown rice but the difference was insufficient to explain t he increase in large bowel digesta mass. In pigs with a cecal cannula, dige sta starch concentrations were equally higher when white or brown rice was fed compared with the corresponding rice which had been finely milled, indi cating that particle size was a determinant of ileal digestibility. Concent rations and pools of total and individual SCFA were higher in all regions o f the colon but not the cecum of pigs fed brown rice. Large bowel Ca2+ conc entrations were lower in pigs fed brown rice, suggesting greater absorption . The data confirm earlier findings that brown rice raises large bowel dige sta mass and SCFA through greater fermentation of starch but show that star ch itself makes a relatively small contribution to digesta and stool mass. Apparently, the rate of passage of digesta is a determinant of the concentr ations and pools of SCFA in the distal colon and in feces.