Effect of refined corn bran (RCB) on growth rate in rats and its morphological and chemical changes in the gastrointestinal tract

Wet milled corn bran (pericarp) was mechanically refined for use as a new source of dietary fiber. Refined corn bran (RCB) was found to contain 85. 2% of neutral detergent fiber (NDF) as its main component. The effect of RCB on both growth rate and the digestibility of certain nutrients, and the changes in its chemical and morphological properties were examined in rats fed diets containing RCB at 5% or 10% as NDF for 4 weeks. Dietary RCB at either level did not depress the growth of wean ing rats, but showed a tendency to decrease dietary protein efficiency. The dietary addition of RCB at higher levels significantly reduced the food efficiency. In addition, RCB exerted weak inhibitory effects on the intestinal absorption of protein and other components. Apparent digestibility of NDF in RCB was estimated to be 18.5% and 13.8% at lower and higher levels, respectively. Observation of intact and fecal RCBs by scanning electron microscopy indicated that the RCB was made thinner and rough on the inner surface during passage through the digestive tract. The latter finding seems to demonstrate that some noncellulosic substances were removed from the intact RCB in the gut.