Effect of Dietary Fiber Type with Different Viscosity and Fermentability on the Standardized Ileal Digestibility of Amino Acids and Intestinal Digestion of Carbohydrate Component in a Corn-Soybean Meal Diet Fed to Growing Pigs

Two experiments were conducted to determine the effect of 2 dietary fiber with different viscosity and fermentability on the ileal AA digestibility and intestinal digestion and hindgut fermentation of carbohydrate (CHO) component in growing pigs. In Exp. 1, 6 ileal-cannulated gilts (initial BW = 21.4 ± 1.5 kg) were allotted to a replicated 3 × 3 Latin square design with 3 diets and 3 periods. The pigs were provided a corn-soybean meal control diet or a diet with 5% inulin (INU) or carboxymethylcellulose sodium (CMC). The apparent ileal digestibility (AID) of AA was measured. The AID and apparent total tract digestibility (ATTD) of carbohydrate components were also determined in the ileal and fecal samples. In Exp. 2, 6 ileal-cannulated pigs were fed a N-free diet and standardized ileal digestibility (SID) of AA was calculated for 3 diets. The AID and SID of Arg, His, Ile, Leu, Lys, Phe, Thr, and Val were greater (P < 0.05) in the CMC diet than in the control and INU diets. Pigs fed the CMC diet had the greater (P < 0.05) AID and SID of Ala, Asp, Cys, Gly, and Ser compared to the control and INU diets. There was also a tendency (P = 0.09) for the AID of Met to be greater in the CMC diet than in the INU diet. The SID of all AA was not affected by incorporation of 5% INU into the corn-soybean meal diet. Inclusion of 5% CMC in the diet increased (P<0.01) the AID of starch and β-glucan compared to the INU diet. Inclusion of 5% INU (6.3%) in the diet reduced (P<0.01) the AID of soluble non-starch polysaccharides (NSP) compared with the control (20.9%) and CMC (29.7%) group. Addition of 5% CMC in the diet reduced (P<0.01) the ATTD of total CHO, soluble NSP, insoluble NSP, total NSP, and cellulose compared to the control and INU diets. Inclusion of 5% CMC in the diet reduced (P<0.01) the hindgut fermentation of soluble NSP, insoluble NSP, total NSP, β-glucan, and cellulose compared to the control and INU diets. In conclusion, addition of 5% INU into a corn-soybean meal diet had a low digestibility of carbohydrate component in upper gut and high hindgut fermentation for total NSP. In contract, the CMC increased the ileal most AA digestion and reduced total tract digestion and hindgut fermentation of carbohydrate component.