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Effects of inclusion rate of fiber-rich ingredients on apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of GE and on the concentration of DE and ME in mixed diets fed to growing pigs were determined. The hypothesis was that increasing the inclusion rate of fiber decreases digestibility of GE, and thus, the contribution of DE and ME from hindgut fermentation because greater concentrations may reduce the ability of microbes to ferment fiber. Twenty ileal-cannulated pigs (BW: 30.64 ± 2.09 kg) were allotted to a replicated 10 × 4 incomplete Latin Square design with 10 diets and four 26-d periods. There were 2 pigs per diet in each period for a total of 8 replications per diet. A basal diet based on corn and soybean meal (SBM) and a corn-SBM diet with 30% corn starch were formulated. Six additional diets were formulated by replacing 15% or 30% corn starch by 15% or 30% corn germ meal, sugar beet pulp, or wheat middlings, and 2 diets were formulated by including 15% or 30% canola meal in a diet containing corn, SBM, and 30% corn starch. Effects of adding 15% or 30% of each fiber source to experimental diets were analyzed using orthogonal contrasts and t-tests were used to compare inclusion rates within each ingredient. The AID and ATTD of GE and concentration of DE and ME in diets decreased (P < 0.05) with the addition of 15% or 30% canola meal, corn germ meal, sugar beet pulp, or wheat middlings compared with the corn starch diet. However, inclusion rate did not affect the calculated DE and ME or AID and ATTD of GE in any of the ingredients indicating that concentration of DE and ME in ingredients was independent of inclusion rate and utilization of energy from test ingredients was equally efficient between diets with 15% and 30% inclusion. Increased inclusion of fiber in the diet did not influence transit time in the small intestine, but reduced the time of first appearance of digesta in the feces indicating that transit time was reduced in the hindgut of pigs fed high-fiber diets. However, this had no impact on DE and ME or ATTD of GE in test ingredients. In conclusion, fiber reduced the DE and ME in the diet. However, inclusion rate of fiber-rich ingredients in diets did not affect calculated values for DE and ME in feed ingredients indicating that microbial capacity for fermentation of fiber in pigs is not overwhelmed by inclusion of 30% high-fiber ingredients in the diets. [ABSTRACT FROM AUTHOR]

An experiment was conducted to quantify nutrient and fiber fractions of feed ingredients and to determine in vitro apparent ileal digestibility (IVAID) and in vitro apparent total tract digestibility (IVATTD) of DM and OM in each ingredient. Ten ingredients that vary in fiber concentration and composition were used: corn, wheat, soybean meal (SBM), canola meal, distillers dried grains with solubles (DDGS), corn germ meal, copra expellers, sugar beet pulp (SBP), synthetic cellulose (SF), and pectin. Correlations between chemical and physical characteristics of ingredients and IVAID and IVATTD of DM and OM were determined. The physical characteristics measured included bulk density, water-binding capacity (WBC), swelling, and viscosity. The analyzed GE was compared with values for GE calculated from all energy-contributing components. Results indicated that the analyzed chemical composition of most ingredients added to 100% or greater, except for DDGS, SBP, and SF, where nutrients added to only 94.29%, 88.90%, and 96.09%, respectively. The difference between the sum of the calculated GE of the analyzed components and the analyzed GE of the ingredients ranged from -2.25 MJ/kg in DDGS to 1.74 MJ/kg in pectin. No correlation was observed between swelling, WBC, or viscosity and IVAID or IVATTD of DM or OM. The concentration of insoluble dietary fiber (IDF) and total dietary fiber (TDF) was negatively correlated (P < 0.05) with IVAID and IVATTD of DM and OM. There was a tendency for NDF (r = -0.60) and ADF (r = -0.61) to be negatively correlated (P < 0.10) with IVAID of DM. However, no correlation was observed between the concentration of CP, GE, acid-hydrolyzed ether extract, lignin, or soluble dietary fiber and IVAID and IVATTD of DM and OM. The stronger correlations between IDF, TDF, and insoluble non-starch polysaccharides and IVAID and IVATTD of DM and OM than between ADF and NDF and IVAID and IVATTD of DM and OM indicate that the concentration of TDF in feed ingredients is a better predictor of the digestibility of DM and OM than values for NDF and ADF. In conclusion, the calculated GE of some feed ingredients was in agreement with the analyzed GE, which gives confidence that energy-contributing components were accounted for, but for DDGS and SBP, it was not possible to account for all analyzed GE. Concentrations of IDF and TDF, but not the physical characteristics of feed ingredients, may be used to estimate IVAID and IVATTD of DM and OM in feed ingredients. [ABSTRACT FROM AUTHOR]

An experiment was conducted to test the hypothesis that an increased inclusion rate of fiber decreases the contribution of DE and ME from hindgut fermentation. Twenty ileal-cannulated pigs (BW: 30.64 ± 2.09 kg) were allotted to a replicated 10 × 4 incomplete Latin Square design with 10 diets and 4 26-d periods. A basal diet based on corn and soybean meal (SBM) and a corn-SBM diet with 30% corn starch were formulated. Six additional diets were formulated by replacing 15 or 30% corn starch by 15 or 30% corn germ meal (CGM), sugar beet pulp (SBP), or wheat middlings (WM), and 2 diets were formulated by including 15 or 30% canola meal (CM) in a diet containing corn, SBM, and 30% corn starch. Effects of adding 15 or 30% of each fiber source to the corn starch diet were analyzed using orthogonal polynomial contrasts. Two-independent-sample t-tests were used to compare inclusion rates within each ingredient. Results indicated that concentration of ME (kcal/kg) linearly decreased (P < 0.001) from 3,420 kcal/kg in the corn starch diet to 3,348 and 3,305, 3,290 and 3,221, 3,316 and 3,125 and 3,310 and 3,213 kcal/kg as 15 or 30% CM, CGM, SBP, or WM was added to the diet. However, inclusion rate did not affect DE and ME of the ingredients (Table 1). This indicates that DE and ME in ingredients were independent of inclusion rates and utilization of energy from test ingredients was equally efficient in diets with 30% inclusion compared with diets with 15% inclusion. In conclusion, fiber had a negative effect on DE and ME in the diet, but inclusion rate does not affect calculated values for DE and ME in feed ingredients with relatively high concentration of fiber indicating that the microbial capacity for fermentation of fiber in pigs is not overwhelmed by inclusion of 30% high-fiber ingredients in the diets. Table 1. Concentration of DE and ME in canola meal, corn germ meal, sugar beet pulp, and wheat middlings Item, kcal/kg DM Inclusion rate SEM P-value 15% 30% Digestible Energy Canola meal 3,257 3,517 198 0.218 Corn germ meal 3,254 3,314 165 0.722 Sugar beet pulp 3,027 2,839 197 0.357 Wheat middlings 3,181 3,319 198 0.495 Metabolizable Energy Canola meal 3,235 3,377 167 0.410 Corn germ meal 3,024 3,290 182 0.165 Sugar beet pulp 3,032 2,729 190 0.136 Wheat middlings 3,197 3,244 198 0.817 [ABSTRACT FROM AUTHOR]

The objective was to determine the apparent ileal digestibility (AID), apparent hindgut disappearance (AHD), and the apparent total tract digestibility (ATTD) of DM, energy, and nutrients by growing pigs fed mixed diets containing increasing concentrations of dietary fiber. Twenty ileal-cannulated pigs (BW: 30.64 ± 2.09 kg) were allotted to a replicated 10 × 4 incomplete Latin Square design with 10 diets and 4 26-d periods. A basal diet based on corn and soybean meal (SBM) and a corn-SBM diet with 30% corn starch were formulated. Six diets were formulated by replacing 15 or 30% corn starch by 15 or 30% corn germ meal (CGM), sugar beet pulp (SBP), or wheat middlings (WM). Two additional diets were formulated by including 15 or 30% canola meal (CM) in a diet containing corn, SBM, and 30% corn starch. Effects of adding 15 or 30% of each fiber source to the corn starch diet were analyzed using orthogonal polynomial contrasts. Results indicated a linear reduction (P < 0.001) of AID of DM from 76.8% in the corn starch diet to 73.7 and 65.6%, 65.9 and 56.0%, 61.4 and 48.6%, and 66.1 and 62.1% in diets containing 15 and 30% CM, CGM, SBP, or WP. The ATTD of DM linearly decreased (P < 0.05) from 93.6% in the corn starch diet to 90.3 and 87.7%, 89.7 and 86.2, 90.7 and 86.8%, and 89.5 and 85.7% as CM, CGM, SBP, or WM were included by 15 or 30% in the diets. The AID of CP was linearly reduced (P < 0.05) by the inclusion of 15 and 30% CM (76.8 and 70.1%), CGM (73.6 and 66.6%), SBP (74.6 and 70.0%), and WM (74.9 and 71.0%) compared with the corn starch diet (79.6%). The ATTD of CP was also reduced (Linear, P < 0.05) with increasing inclusion of test ingredients in the diet. The AHD of DM linearly increased (P < 0.05) from 16.6% in the corn starch diet to 16.5 and 22.2%; 24.0 and 30.1%, 29.2 and 38.1%, and 23.3 and 21.3% as CM, CGM, SBP, or WM were included by 15 or 30% in the diets. In conclusion, increasing concentrations of fiber in the diet may result in increased hindgut fermentation of some nutrients but this may also reduce AID and ATTD of DM and CP. [ABSTRACT FROM AUTHOR]