Nondietary Gut Materials Interfere with the Determination of Dietary Fiber Digestibility in Growing XXXX When Using the Prosky Method.

@entity1707 @entity62 @entity6701
BACKGROUND: Reported negative ileal and total tract dietary fiber (DF) digestibility values are physiologically untenable and suggest the presence of nondietary material in the gut contents that interferes with the DF determination. OBJECTIVE: The objective of this study was to demonstrate the importance of interfering material (IM) when the Prosky method was used to determine DF digestibility. METHODS: Fourteen @entity1707 (41.6    3.0 kg) were surgically implanted with ileal T-cannulas. A semisynthetic fiber-free diet and 2 semisynthetic diets containing kiwifruit as the sole fiber source [25 or 50 g fiber/kg @entity62 ( @entity62 )] were prepared. @entity6701 was used as an indigestible marker. @entity1707 were fed the kiwifruit-containing diets (n=7 per diet) for 44 d, followed by the fiber-free diet (n=14) for 7 d. Ileal digesta and feces were collected over 3 d, starting on days 42 and 49. The flow of IM and the soluble, insoluble, and total DF digestibility were determined. RESULTS: Considerable amounts of IM were present when the Prosky method was applied to ileal digesta (12 g/kg @entity62 intake) and feces (28 g/kg @entity62 intake) collected from @entity1707 fed the fiber-free diet after adaptation to the diet containing 50 g/kg @entity62 of fiber. The @entity1707 adapted to the highest fiber concentration had 0.9- and 0.7-fold greater ileal and fecal IM flows than their counterparts adapted to the lowest concentration. In the ileal digesta, crude mucin was the main IM source in the soluble DF fraction (66%). In the ileal digesta and feces, microbial cells were the main IM source in the insoluble DF fraction. The determined ileal soluble DF and total tract insoluble DF digestibilities increased by 44-54% and 78% respectively after correction for IM (P < 0.001). CONCLUSIONS: Large amounts of IM are present in ileal digesta and feces of @entity1707 when fiber is determined with the Prosky method, leading to a marked underestimation.
