Effects of inclusion rate of high fiber dietary ingredients on apparent ileal, hindgut, and total tract digestibility of dry matter and nutrients in ingredients fed to growing pigs

Animal Feed Science and Technology 248 (2019) 1–9

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Effects of inclusion rate of high fiber dietary ingredients on apparent ileal, hindgut, and total tract digestibility of dry matter and nutrients in ingredients fed to growing pigs

T

D.M.D.L. Navarroa, E.M.A.M. Bruininxb,c, L. de Jongc, H.H. Steina,d,

⁎

a

Department of Animal Sciences, University of Illinois, Urbana, 61801, United States Animal Nutrition Group, Wageningen University, the Netherlands c Agrifirm Innovation Center, Royal Dutch Agrifirm, Apeldoorn, the Netherlands d Division of Nutritional Sciences, University of Illinois, Urbana, 61801, United States b

ARTICLE INFO

ABSTRACT

Keywords: Digestibility Fiber Pigs

An experiment was conducted to determine if values for the coefficient of ileal apparent digestibility (CIAD), the coefficient of hindgut apparent disappearance (CHAD), and the coefficient of total tract apparent digestibility (CTTAD) of dry matter (DM) and nutrients in high-fiber ingredients measured at 150 g/kg inclusion are also accurate if measured at 300 g/kg inclusion in diets fed to pigs. The second objective was to confirm that most of the insoluble dietary fiber (IDF) is not fermented by growing pigs. 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 corn and soybean meal (SBM) basal diet and a corn-SBM diet with 300 g/kg corn starch were formulated. Six diets were formulated by replacing 150 or 300 g/kg corn starch by 150 or 300 g/kg corn germ meal (CGM), sugar beet pulp (SBP), or wheat middlings (WM). Two additional diets were formulated by adding 150 or 300 g/kg canola meal (CM) to the diet containing corn, SBM, and 300 g/kg corn starch at the expense of corn and SBM. Effects of inclusion rate of each fiber source in the diet on CIAD, CHAD, and CTTAD of DM and nutrients were analyzed using orthogonal contrasts. Independent t-tests were used to compare inclusion rates within each ingredient. Results indicated that CIAD and CHAD of CP, acid hydrolyzed ether extract (AEE), and most fiber fractions in CM decreased (P < 0.05) as inclusion level increased from 150 to 300 g/kg, but that was not the case for CGM, SBP, or WM. The CTTAD of DM, organic matter (OM), AEE, and soluble dietary fiber (SDF) in CGM increased (P < 0.05) if 300 g/kg rather than 150 g/kg was included in the diet and CTTAD of DM, OM, acid detergent fiber, and SDF in WM increased (P < 0.05) as inclusion level increased. No differences in CTTAD of DM and nutrients in CM and SBP were observed between inclusion rates. The CTTAD of IDF ranged from 0.529 in WM included at 150 g/kg to 0.862 in SBP included at 300 g/kg in the diet. In conclusion, CIAD, CHAD,

Abbreviations: ADF, acid detergent fiber; AEE, acid-hydrolyzed ether extract; CGM, corn germ meal; CHAD, coefficient of hindgut apparent disappearance; CIAD, coefficient of ileal apparent digestibility; CM, canola meal; CP, crude protein; CTTAD, coefficient of total tract apparent digestibility; DE, digestible energy; DM, dry matter; IDF, insoluble dietary fiber; ME, metabolizable energy; NDF, neutral detergent fiber; NSP, nonstarch polysaccharides; OM, organic matter; SBM, soybean meal; SBP, sugar beet pulp; SDF, soluble dietary fiber; SEM, standard error of the mean; TDF, total dietary fiber; WM, wheat middlings ⁎ Corresponding author at: Department of Animal Sciences, University of Illinois, Urbana, 61801, United States. E-mail address: [email protected] (H.H. Stein). https://doi.org/10.1016/j.anifeedsci.2018.12.001 Received 29 April 2018; Received in revised form 26 July 2018; Accepted 5 December 2018 0377-8401/ © 2018 Elsevier B.V. All rights reserved.

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and CTTAD of most nutrients in test ingredients is not different between 150 and 300 g/kg inclusion rate. Under the conditions of this experiment, there was relatively high digestibility of IDF.

1. Introduction Dietary fiber is generally not well utilized by pigs, but soluble dietary fiber (SDF) can easily be fermented to synthesize volatile fatty acids that contribute to the energy status of the animal (Urriola et al., 2013). However, results of some studies have indicated that the digestibility of insoluble dietary fiber (IDF) is greater than previously thought (Jaworski and Stein, 2017; Navarro et al., 2018a), which indicates that digestibility of fiber may have traditionally been underestimated. Increased concentration of dietary fiber in the diet may negatively affect digestibility of dry matter (DM) and nutrients (Urriola et al., 2013). It is possible that dietary fiber reduces digestibility of DM and nutrients by reducing transit time of digesta in the gastrointestinal tract of the pig (Wilfart et al., 2007; Navarro et al., 2018b). However, the concentration of digestible energy (DE) and metabolizable energy (ME) in canola meal, corn germ meal, sugar beet pulp, and wheat middlings was not different between 150 and 300 g/kg inclusion rate in the diet (Navarro et al., 2018b). It is not known if the coefficient of ileal apparent digestibility (CIAD), the coefficient of hindgut apparent disappearance (CHAD), and the coefficient of total tract apparent digestibility (CTTAD) of DM and nutrients in high fiber dietary ingredients are also not affected by inclusion rate in the diet. Therefore, the first objective of this experiment was to determine if values for the CIAD, CHAD, and CTTAD of DM and nutrients in 4 high-fiber ingredients measured at Table 1 Composition of experimental diets, g/kg unless otherwise indicated, as-fed basis. Ingredient

Ground corn Soybean meal Corn starch Test ingredient Ground limestone Monocalcium phosphate Sodium chloride Vitamin-mineral premixb Titanium dioxide Analyzed values Gross energy, MJ/kg Dry matter Ash Organic matter Crude protein AEEc Neutral detergent fiber Acid detergent fiber Acid detergent lignin Total dietary fiber Insoluble dietary fiber Soluble dietary fiber Cellulosed Insoluble hemicellulosese NSPf Insoluble NSPg Non-cellulosic NSPh

Canola meal

Corn germ meal

Sugar beet pulp

Wheat middlings

Basal

CSa

150

300

150

300

150

300

150

300

570.0 402.0 – – 9.0 8.0 4.0 3.0 4.0

394.0 278.0 300.0 – 10.0 7.0 4.0 3.0 4.0

307.5 216.5 300.0 150.0 8.0 7.0 4.0 3.0 4.0

221.0 156.0 300.0 300.0 7.0 5.0 4.0 3.0 4.0

394.0 278.0 150.0 150.0 10.0 7.0 4.0 3.0 4.0

394.0 278.0 – 300.0 10.0 7.0 4.0 3.0 4.0

396.0 279.0 150.0 150.0 7.0 7.0 4.0 3.0 4.0

396.0 279.0 – 300.0 7.0 7.0 4.0 3.0 4.0

394.0 278.0 150.0 150.0 12.0 5.0 4.0 3.0 4.0

394.0 278.0 – 300.0 12.0 5.0 4.0 3.0 4.0

16.2 871.9 54.2 817.7 228.4 24.1 68.7 34.1 5.4 111.4 105.5 5.9 28.7 34.5 106.0 100.1 77.3

15.9 877.0 44.9 832.1 156.5 18.3 44.6 21.5 3.0 82.5 76.4 6.0 18.5 23.1 79.5 73.5 61.0

16.0 874.9 49.2 825.6 179.7 20.6 73.9 43.8 14.2 113.4 109.2 4.2 29.6 30.1 99.2 95.0 69.6

16.2 877.4 52.8 824.6 217.2 22.0 94.5 62.9 23.2 127.4 120.7 6.7 39.7 31.6 104.2 97.5 64.5

16.2 879.1 52.7 826.4 204.7 17.6 101.9 43.8 9.8 131.7 125.6 6.1 34.0 58.0 121.9 115.8 87.9

16.4 876.3 52.2 824.1 227.9 24.0 156.2 64.3 17.6 192.9 176.4 16.4 46.7 91.9 175.2 158.8 128.6

16.0 880.3 53.0 827.3 168.3 17.5 97.6 59.5 9.3 157.7 135.4 22.3 50.2 38.1 148.5 126.1 98.2

15.9 878.4 63.9 814.5 179.0 19.2 151.6 97.1 15.4 267.0 216.2 50.8 81.8 54.5 251.7 200.9 169.9

16.0 875.8 54.2 821.6 175.1 20.3 98.8 33.8 7.7 133.6 130.3 3.2 26.1 65.0 125.9 122.6 99.8

16.2 872.9 58.6 814.3 197.4 25.9 145.7 47.9 12.0 197.9 188.0 9.9 35.9 97.7 185.8 176.0 149.9

a

CS = corn starch diet. The vitamin-micromineral premix provided the following quantities of vitamins and micro minerals per kilogram of complete diet: Vitamin A as retinyl acetate, 11,136 IU; vitamin D3 as cholecalciferol, 2208 IU; vitamin E as DL-alpha tocopheryl acetate, 66 IU; vitamin K as menadione dimethylprimidinol bisulfite, 1.42 mg; thiamin as thiamine mononitrate, 0.24 mg; riboflavin, 6.59 mg; pyridoxine as pyridoxine hydrochloride, 0.24 mg; vitamin B12, 0.03 mg; D-pantothenic acid as D-calcium pantothenate, 23.5 mg; niacin, 44.1 mg; folic acid, 1.59 mg; biotin, 0.44 mg; Cu, 20 mg as copper sulfate and copper chloride; Fe, 126 mg as ferrous sulfate; I, 1.26 mg as ethylenediamine dihydriodide; Mn, 60.2 mg as manganese sulfate; Se, 0.3 mg as sodium selenite and selenium yeast; and Zn, 125.1 mg as zinc sulfate. c AEE = acid hydrolyzed ether extract. d Cellulose = acid detergent fiber – acid detergent lignin. e Insoluble hemicelluloses = neutral detergent fiber – acid detergent fiber. f NSP = non-starch polysaccharides, total dietary fiber – acid detergent lignin. g Insoluble NSP = NSP – soluble dietary fiber. h Non-cellulosic NSP = NSP – Cellulose. b

2

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150 g/kg inclusion are also accurate if 300 g/kg of that ingredient is included. The hypothesis was that increasing concentrations of high fiber dietary ingredients results in a linear reduction in digestibility of DM and nutrients in mixed diets, but that the CIAD, CHAD, and CTTAD of DM and nutrients in ingredients is not different between 150 and 300 g/kg inclusion rates. The second objective was to determine the location and extent of fiber fermentation in growing pigs. The hypothesis was that fermentation of dietary fiber occurs mainly in the hindgut and that most of the SDF is fermented, whereas most of the IDF is not. 2. Materials and methods The Institutional Animal Care and Use Committee at the University of Illinois reviewed and approved the protocol for this experiment. Pigs were the offspring of Line 359 boars mated to Camborough females (Pig Improvement Company, Hendersonville, TN). 2.1. Animals and experimental design Twenty ileal-cannulated pigs (initial 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. Experimental diets, feeding, data recording, and sample collection were discussed in detail by Navarro et al. (2018b). All diets were fed in a mash form. 2.2. Chemical analysis Diets, ingredients, ileal digesta, and fecal samples were analyzed for DM, ash, gross energy, crude protein (CP), acid hydrolyzed ether extract (AEE), acid detergent fiber (ADF), neutral detergent fiber (NDF), acid detergent lignin, IDF, and SDF using standard procedures described by (Navarro et al., 2018b; Tables 1 and 2). Total dietary fiber (TDF) in all samples was determined as the sum of IDF and SDF analyses using the AnkomTDF Dietary Fiber Analyzer (AOAC 991.43, AOAC International, 2007; Ankom Technology, Macedon, NY). The concentration of titanium in diets and ileal digesta samples were measured following the procedure of Myers et al. (2004). 2.3. Calculations and statistical analysis By analyzing for the 5 fiber components in diets, ingredients, ileal digesta, and fecal samples (i.e., NDF, ADF, acid detergent lignin, IDF, and SDF) it was possible to calculate the concentrations of TDF, cellulose, insoluble hemicellulose, non-starch polysaccharides (NSP), insoluble NSP, and non-cellulosic NSP (Table 3). Apparent ileal digestibility of TDF in the diets was calculated as described by Stein et al. (2007) using Eq. (1): Table 2 Analyzed nutrient composition and particle size of corn, soybean meal, canola meal, corn germ meal, sugar beet pulp, and wheat middlings, g/kg unless otherwise indicated, as-fed basis. Item

Corn

Soybean meal

Canola meal

Corn germ meal

Sugar beet pulp

Wheat middlings

Particle size, μm Gross energy, MJ/kg Dry matter Ash Organic matter Starch Crude protein AEEa Neutral detergent fiber Acid detergent fiber Acid detergent lignin Total dietary fiber Insoluble dietary fiber Soluble dietary fiber Celluloseb Insoluble hemicellulosesc NSPd Insoluble NSPe Non-cellulosic NSPf

412 15.7 845.2 10.3 834.9 622.9 47.8 33.5 62.0 19.2 3.9 82.7 78.6 4.1 15.3 42.7 78.8 74.7 63.4

602 17.9 901.9 64.1 837.9 15.4 493.3 16.8 88.0 57.6 2.1 143.8 129.8 14.0 55.5 30.5 141.7 127.7 86.2

512 17.9 889.0 71.4 817.6 18.7 405.2 40.6 236.3 173.3 73.9 264.2 254.4 9.8 99.4 63.0 190.3 180.5 90.9

466 17.3 882.4 32.9 849.5 186.3 237.0 31.2 373.7 143.1 45.0 358.9 334.1 24.8 98.1 230.6 313.9 289.1 215.8

442 15.7 924.8 69.6 855.2 38.8 72.7 20.0 454.7 215.4 24.6 485.4 445.7 39.7 190.8 239.3 460.8 421.1 270.0

513 16.9 875.3 49.0 826.3 228.0 143.0 44.4 351.8 102.6 33.9 346.5 336.8 9.6 68.7 249.3 312.6 303.0 243.9

a b c d e f

AEE = acid hydrolyzed ether extract. Cellulose = acid detergent fiber – acid detergent lignin. Insoluble hemicelluloses = neutral detergent fiber – acid detergent fiber. NSP = non-starch polysaccharides, total dietary fiber – acid detergent lignin. Insoluble NSP = NSP – soluble dietary fiber. Non-cellulosic NSP = NSP – Cellulose. 3

Animal Feed Science and Technology 248 (2019) 1–9

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Table 3 Quantification of fiber fractions in feed ingredients. Component

Procedure

Insoluble dietary fiber Soluble dietary fiber Total dietary fiber Acid detergent lignin Acid detergent fiber Neutral detergent fiber Cellulose Insoluble hemicelluloses Soluble hemicelluloses Non-starch polysaccharides Soluble NSP Insoluble NSP Non-cellulosic NSP

Analyzed Analyzed Calculated Analyzed Analyzed Analyzed Calculated Calculated Calculated Calculated Calculated Calculated Calculated

(insoluble + soluble dietary fiber)

(acid detergent fiber – acid detergent lignin) (neutral detergent fiber – acid detergent fiber) (soluble hemicellulose = soluble dietary fiber) (total dietary fiber – acid detergent lignin) (soluble NSP = soluble dietary fiber) (NSP – soluble NSP) (NSP – cellulose)

CIAD = [1 – {(TDFd/TDFf) × (TiO2f/ TiO2d)}] × 100

(1)

where CIAD is the apparent ileal digestibility value of total dietary fiber (%), TDFd is the analyzed TDF of the ileal digesta DM, TDFf is the analyzed TDF of feed DM, TiO2f is the concentration of titanium in the feed DM, and TiO2d is the concentration of titanium in the ileal digesta DM. The CIAD of DM and all other nutrients in each diet was also calculated using this equation. The CTTAD of DM and nutrients in each diet were also calculated (Adeola, 2001). The CIAD and CTTAD of nutrients in ingredients were calculated using the difference procedure (Widmer et al., 2007) with the exception that CIAD and CTTAD of DM and OM were calculated as described by Navarro et al. (2018b). The digestibility of DM and nutrients in the corn-soybean meal diet was used to calculate the contribution of corn and soybean meal to the digestibility of DM and nutrients in all other diets and the digestibility of DM and nutrients in test ingredients for each inclusion level was calculated by difference (Widmer et al., 2007). Apparent hindgut disappearance was calculated as the difference between CTTAD and CIAD. Data were analyzed using SAS with pig as the experimental unit (SAS Institute Inc., Cary, NC). Homogeneity of the variances was confirmed using the UNIVARIATE procedure in PROC MIXED. The BOXPLOT procedure of SAS was used to check for outliers. Analysis of variance was used with the MIXED procedure. Diet was the fixed effect and period, replicate, and pig within replicate were random effects. Least squares means were calculated using a Least Significant Difference test and effects of adding 150 or 300 g/ Table 4 Coefficient of ileal apparent digestibility of dry matter and nutrients in experimental dietsa. Itemb

d

DM OMd CPd AEEe NDFf ADF TDFg IDFg SDFg Cellulose Ins. Hemih NSPg Ins. NSPi NC NSPi

Canola meal c

Corn germ meal

Sugar beet pulp

Wheat middlings

Pooled

Basal

CS

150

300

150

300

150

300

150

300

SEM

0.641 0.671 0.770 0.273 −0.010 0.020 0.041 0.139 −1.622 −0.020 −0.036 0.031 0.136 0.053

0.768 0.793 0.796 0.439 0.007 −0.011 0.228 0.282 −0.427 −0.021 0.021 0.243 0.300 0.321

0.737 0.763 0.768 0.550 0.159 0.048 0.253 0.322 −1.545 0.027 0.319 0.277 0.355 0.382

0.656 0.692 0.701 0.442 0.015 −0.109 0.062 0.134 −1.200 −0.118 0.266 0.096 0.190 0.230

0.659 0.687 0.736 0.196 0.171 0.098 0.126 0.181 −0.905 0.042 0.230 0.111 0.174 0.140

0.560 0.594 0.666 0.229 0.237 0.087 0.177 0.173 −0.112 −0.007 0.348 0.132 0.156 0.183

0.614 0.657 0.746 0.235 0.054 0.009 0.069 0.203 −0.688 −0.022 0.121 0.062 0.201 0.103

0.486 0.545 0.700 0.217 0.139 0.083 0.164 0.272 −0.277 0.057 0.240 0.160 0.276 0.211

0.661 0.689 0.749 0.222 0.166 −0.067 0.159 0.245 −3.339 −0.078 0.283 0.170 0.261 0.235

0.621 0.653 0.710 0.362 0.291 0.093 0.289 0.352 −0.886 0.076 0.392 0.299 0.369 0.353

0.0268 0.0253 0.0220 0.0902 0.0927 0.0810 0.0689 0.0698 0.2145 0.0822 0.1123 0.0694 0.0704 0.0691

a

Data are means of 8 observations per treatment except for the diet with 150 g/kg sugar beet pulp where only 7 observations were used. DM = dry matter; OM = organic matter; CP = crude protein; AEE = acid hydrolyzed ether extract; NDF = neutral detergent fiber; ADF = acid detergent fiber; TDF = total dietary fiber; IDF = insoluble dietary fiber; SDF = soluble dietary fiber; Ins. Hemi = insoluble hemicelluloses; NSP = non-starch polysaccharides; Ins. NSP = insoluble non-starch polysaccharides; NC NSP = non-cellulosic non-starch polysaccharides. c CS = corn starch diet. d Linear reduction (P < 0.001) for inclusion of 150 or 300 g/kg canola meal, corn germ meal, sugar beet pulp, or wheat middlings. e Linear reduction (P < 0.05) for inclusion of 150 or 300 g/kg corn germ meal or sugar beet pulp. f Linear increase (P < 0.05) for inclusion of 150 or 300 g/kg corn germ meal or wheat middlings. g Linear reduction (P < 0.05) for inclusion of 150 or 300 g/kg canola meal. h Linear increase (P < 0.05) for inclusion of 150 or 300 g/kg canola meal, corn germ meal, sugar beet pulp, or wheat middlings. i Linear reduction (P < 0.05) for inclusion of 150 or 300 g/kg corn germ meal. b

4

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kg of each fiber source to the corn-soybean meal-corn starch basal diet were analyzed using orthogonal contrasts. Two-independentsample t-tests were conducted using the TTEST procedure to compare response variables between 150 and 300 g/kg inclusion rates within each ingredient. Results were considered significant at P < 0.05. 3. Results 3.1. CIAD of DM and nutrients in diets and ingredients The CIAD of DM, OM, and CP decreased (linear, P < 0.05) and the CIAD of insoluble hemicelluloses increased (linear, P < 0.05) with addition of 150 or 300 g/kg canola meal, corn germ meal, sugar beet pulp, or wheat middlings to the corn starch diet (Table 4). Addition of 150 or 300 g/kg corn germ meal or sugar beet pulp reduced (linear, P < 0.05) the CIAD of AEE compared with the corn starch diet. The CIAD of NDF increased (linear, P < 0.05) with addition of 150 or 300 g/kg corn germ meal or wheat middlings compared with the corn starch diet. The CIAD of TDF, IDF, SDF, and NSP decreased (linear, P < 0.05) with addition of canola meal and the CIAD of insoluble NSP and non-cellulosic NSP decreased (linear, P < 0.05) with inclusion of corn germ meal in the corn starch diet. The CIAD of CP, AEE, TDF, IDF, NSP, insoluble NSP, and non-cellulosic NSP in canola meal decreased (P < 0.05) as inclusion level increased from 150 to 300 g/kg, but not in corn germ meal, sugar beet pulp, or wheat middlings (Table 5). The CIAD of SDF in wheat middlings increased (P < 0.05) as inclusion level increased from 150 to 300 g/kg, but that was not the case in canola meal, corn germ meal, or sugar beet pulp. No differences in CIAD of DM, OM, NDF, ADF, cellulose, or insoluble hemicelluloses were observed in any of the test ingredients as inclusion level increased from 150 to 300 g/kg. 3.2. CHAD of DM and nutrients in diets and ingredients The CHAD of DM and OM increased (linear, P < 0.05) with addition of canola meal, corn germ meal, sugar beet pulp, or wheat middlings to the corn starch diet (Table 6) and the CHAD of CP increased (linear, P < 0.05) with addition of canola meal to the corn starch diet. The CHAD of non-cellulosic NSP increased (linear, P < 0.05) with addition of canola meal, corn germ meal, or sugar beet pulp to the corn starch diet. The CHAD of NSP increased (linear, P < 0.05) with addition of sugar beet pulp but decreased (linear, P < 0.05) with addition of wheat middlings to the corn starch diet. The CHAD of NDF and ADF decreased (linear, P < 0.05) with addition of canola meal or wheat middlings to the corn starch diet and inclusion of wheat middlings reduced (linear, P < 0.01) the CHAD of TDF, IDF, cellulose, insoluble hemicelluloses, NSP, and insoluble NSP. The CHAD of CP, AEE, TDF, IDF, insoluble hemicelluloses, NSP, insoluble NSP, and non-cellulosic NSP in canola meal increased (P < 0.05) as inclusion level increased from 150 to 300 g/kg, but no changes in the CHAD of these nutrients were observed in corn germ meal, sugar beet pulp, or wheat middlings (Table 7). The CHAD of SDF in wheat middlings decreased (P < 0.05) as inclusion rate increased from 150 to 300 g/kg, but no change in CHAD of SDF was calculated for canola meal, corn germ meal, or sugar beet pulp. No differences in CHAD of DM, OM, NDF, ADF, or cellulose were observed in any of the test ingredients as inclusion level increased from 150 to 300 g/kg. Table 5 Coefficient of ileal apparent digestibility of dry matter and nutrients in ingredients at 150 or 300 g/kg inclusion ratea. Itemb

DM OM CP AEE NDF ADF TDF IDF SDF Cellulose Ins. Hemi. NSP Ins. NSP NC NSP

Canola meal

Corn germ meal

Sugar beet pulp

Wheat middlings

150

300

SEM

150

300

SEM

150

300

SEM

150

300

SEM

0.410 0.444 0.763 1.256 0.341 0.069 0.575 0.605 −1.410 0.079 1.048 0.768 0.815 1.396

0.233 0.284 0.644 0.616 0.016 −0.146 0.067 0.120 −0.771 −0.160 0.458 0.136 0.212 0.415

0.121 0.117 0.048* 0.177* 0.177 0.143 0.153* 0.139* 0.940 0.174 0.292 0.177* 0.159* 0.199*

0.304 0.339 0.537 0.010 0.312 0.179 0.239 0.232 −0.178 0.110 0.392 0.227 0.217 0.277

0.508 0.547 0.430 0.209 0.341 0.126 0.283 0.202 0.763 0.002 0.471 0.211 0.175 0.292

0.098 0.096 0.093 0.345 0.115 0.108 0.134 0.141 0.750 0.134 0.131 0.150 0.159 0.168

0.139 0.251 0.427 0.326 0.127 0.018 0.116 0.310 −0.061 −0.002 0.277 0.115 0.323 0.196

0.383 0.460 0.171 0.165 0.190 0.107 0.229 0.346 0.168 0.084 0.329 0.229 0.355 0.316

0.106 0.106 0.246 0.438 0.079 0.078 0.104 0.103 0.131 0.081 0.098 0.107 0.111 0.139

0.371 0.404 0.409 0.180 0.329 −0.197 0.334 0.407 −8.255 −0.188 0.501 0.388 0.467 0.505

0.602 0.666 0.473 0.549 0.422 0.145 0.467 0.498 0.228 0.163 0.520 0.501 0.535 0.565

0.170 0.177 0.288 0.392 0.143 0.184 0.158 0.166 0.635* 0.226 0.130 0.167 0.175 0.157

* 150 g/kg and 300 g/kg values differ (P < 0.05). a Data are means of 8 observations per treatment except for the diet with 150 g/kg sugar beet pulp where only 7 observations were used. b DM = dry matter; OM = organic matter; CP = crude protein; AEE = acid hydrolyzed ether extract; NDF = neutral detergent fiber; ADF = acid detergent fiber; TDF = total dietary fiber; IDF = insoluble dietary fiber; SDF = soluble dietary fiber; Ins. Hemi = insoluble hemicelluloses; NSP = non-starch polysaccharides; Ins. NSP = insoluble non-starch polysaccharides;NC NSP = non-cellulosic non-starch polysaccharides. 5

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Table 6 Coefficient of hindgut apparent disappearance of dry matter and nutrients in experimental dietsa. Itemb

DMd OMd CPe AEE NDFf ADFf TDFg IDFg SDF Celluloseg Ins. Hemi.g NSPh Ins. NSPg NC NSPi

Canola meal

Corn germ meal

Sugar beet pulp

Wheat middlings

Pooled

Basal

CSc

150

300

150

300

150

300

150

300

SEM

0.278 0.263 0.145 0.163 0.759 0.790 0.756 0.670 2.237 0.871 0.723 0.775 0.685 0.737

0.166 0.155 0.115 −0.019 0.679 0.752 0.554 0.505 1.153 0.850 0.611 0.560 0.510 0.475

0.165 0.158 0.109 −0.064 0.404 0.460 0.449 0.387 2.046 0.646 0.324 0.503 0.435 0.442

0.222 0.210 0.168 0.115 0.479 0.508 0.574 0.510 1.720 0.720 0.422 0.669 0.596 0.637

0.240 0.230 0.143 −0.006 0.572 0.650 0.640 0.598 1.455 0.774 0.510 0.673 0.629 0.632

0.301 0.285 0.155 0.062 0.518 0.658 0.630 0.604 0.904 0.805 0.414 0.666 0.642 0.616

0.292 0.266 0.136 −0.031 0.719 0.810 0.753 0.608 1.563 0.914 0.580 0.785 0.637 0.724

0.381 0.345 0.131 −0.115 0.644 0.744 0.689 0.571 1.180 0.839 0.463 0.716 0.596 0.657

0.233 0.223 0.169 0.215 0.440 0.576 0.522 0.448 3.544 0.693 0.374 0.544 0.465 0.505

0.213 0.202 0.142 0.095 0.265 0.329 0.341 0.278 1.524 0.454 0.232 0.366 0.299 0.344

0.028 0.027 0.025 0.111 0.106 0.089 0.077 0.076 0.226 0.091 0.135 0.078 0.077 0.077

a

Data are means of 8 observations per treatment except for the diet with 150 g/kg sugar beet pulp where only 7 observations were used. DM = dry matter; OM = organic matter; CP = crude protein; AEE = acid hydrolyzed ether extract; NDF = neutral detergent fiber; ADF = acid detergent fiber; TDF = total dietary fiber; IDF = insoluble dietary fiber; SDF = soluble dietary fiber; Ins. Hemi = insoluble hemicelluloses; NSP = non-starch polysaccharides; Ins. NSP = insoluble non-starch polysaccharides; NC NSP = non-cellulosic non-starch polysaccharides. c CS = corn starch diet. d Linear increase (P < 0.05) for inclusion of 150 or 300 g/kg canola meal, corn germ meal, sugar beet pulp, or wheat middlings. e Linear increase (P < 0.05) for inclusion of 150 or 300 g/kg canola meal. f Linear decrease (P < 0.05) for inclusion of 150 or 300 g/kg canola meal or wheat middlings. g Linear decrease (P < 0.01) for inclusion of 150 or 300 g/kg wheat middlings. h Linear increase (P < 0.05) for sugar beet pulp but linear decrease (P < 0.01) for wheat middlings with inclusion of 150 or 300 g/kg of ingredient. i Linear increase (P < 0.05) for inclusion of 150 or 300 g/kg canola meal, corn germ meal, or sugar beet pulp. b

Table 7 Coefficient of hindgut apparent disappearance of dry matter and nutrients in ingredients at 150 or 300 g/kg inclusion ratea. Itemb

DM OM CP AEE NDF ADF TDF IDF SDF Cellulose Ins. Hemi. NSP Ins. NSP NC NSP

Canola meal

Corn germ meal

Sugar beet pulp

Wheat middlings

150

300

SEM

150

300

SEM

150

300

SEM

150

300

SEM

0.284 0.288 −0.032 −0.638 0.020 0.219 −0.017 −0.038 1.622 0.402 −0.505 −0.044 −0.073 −0.459

0.483 0.472 0.159 0.025 0.384 0.439 0.482 0.433 1.263 0.666 0.234 0.602 0.544 0.542

0.143 0.139 0.060* 0.264* 0.198 0.164 0.182* 0.163* 1.119 0.196 0.319* 0.212* 0.189* 0.251*

0.414 0.411 −0.020 −0.700 0.431 0.502 0.483 0.503 0.621 0.661 0.389 0.527 0.553 0.471

0.316 0.299 0.118 −0.168 0.419 0.580 0.539 0.556 0.153 0.757 0.322 0.582 0.606 0.516

0.096 0.096 0.084 0.461 0.127 0.099 0.146 0.149 0.715 0.140 0.160 0.170 0.176 0.196

0.647 0.563 −0.584 −1.381 0.646 0.790 0.728 0.509 1.099 0.907 0.415 0.772 0.545 0.678

0.451 0.401 −0.198 −0.991 0.604 0.727 0.654 0.516 0.827 0.826 0.379 0.685 0.545 0.604

0.121 0.123 0.333 0.441 0.095 0.081 0.107 0.107 0.140 0.084 0.138 0.112 0.116 0.143

0.330 0.331 0.096 0.268 0.137 0.229 0.176 0.122 7.255 0.333 0.125 0.181 0.123 0.165

0.168 0.186 0.257 0.059 0.089 0.019 0.108 0.076 0.404 0.098 0.123 0.123 0.090 0.14

0.200 0.191 0.345 0.530 0.168 0.223 0.181 0.187 0.527* 0.269 0.15 0.188 0.194 0.173

* 150 g/kg and 300 g/kg values differ (P < 0.05). a Data are means of 8 observations per treatment except for the diet with 150 g/kg sugar beet pulp where only 7 observations were used. b DM = dry matter; OM = organic matter; CP = crude protein; AEE = acid hydrolyzed ether extract; NDF = neutral detergent fiber; ADF = acid detergent fiber; TDF = total dietary fiber; IDF = insoluble dietary fiber; SDF = soluble dietary fiber; Ins. Hemi = insoluble hemicelluloses; NSP = non-starch polysaccharides; Ins. NSP = insoluble non-starch polysaccharides; NC NSP = non-cellulosic non-starch polysaccharides.

3.3. CTTAD of DM and nutrients in diets and ingredients The CTTAD of DM, OM, and CP decreased (linear, P < 0.05) with addition of canola meal, corn germ meal, sugar beet pulp, or wheat middlings to the corn starch diet (Table 8). The CTTAD of AEE increased (linear, P < 0.05) with addition of canola meal or wheat middlings, but decreased (linear, P < 0.05) with addition of corn germ meal and sugar beet pulp to the diet. In contrast, the CTTAD of NDF decreased (P < 0.05) with addition of canola meal or wheat middlings to the corn starch diet, but increased (linear, P < 0.05) with addition of corn germ meal or sugar beet pulp. The CTTAD of ADF, TDF, IDF, SDF, and cellulose decreased 6

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Table 8 Coefficient of total tract apparent digestibility of dry matter and nutrients in experimental dietsa. Itemb

DMd OMd CPd AEEe NDFf ADFg TDFg IDFg SDFh Celluloseg Ins. Hemii NSPj Ins. NSPj NC NSPk

Canola meal

Corn germ meal

Sugar beet pulp

Wheat middlings

Pooled

Basal

CSc

15%

30%

15%

30%

15%

30%

15%

30%

SEM

0.916 0.933 0.917 0.428 0.747 0.812 0.792 0.802 0.618 0.848 0.690 0.803 0.814 0.788

0.936 0.950 0.912 0.420 0.685 0.742 0.780 0.785 0.701 0.829 0.632 0.802 0.809 0.796

0.903 0.922 0.880 0.491 0.563 0.508 0.703 0.711 0.490 0.672 0.643 0.780 0.793 0.825

0.877 0.900 0.868 0.557 0.497 0.399 0.638 0.644 0.541 0.605 0.693 0.768 0.784 0.869

0.897 0.914 0.869 0.183 0.744 0.750 0.763 0.775 0.526 0.818 0.740 0.784 0.798 0.771

0.862 0.881 0.823 0.291 0.757 0.744 0.780 0.778 0.810 0.796 0.766 0.798 0.797 0.799

0.907 0.924 0.878 0.208 0.769 0.816 0.823 0.815 0.874 0.886 0.696 0.847 0.843 0.827

0.868 0.891 0.831 0.103 0.785 0.829 0.855 0.845 0.898 0.897 0.704 0.878 0.873 0.868

0.895 0.913 0.897 0.437 0.608 0.509 0.683 0.695 0.197 0.616 0.654 0.715 0.729 0.741

0.857 0.878 0.888 0.514 0.589 0.448 0.668 0.671 0.618 0.556 0.657 0.703 0.708 0.739

0.006 0.006 0.011 0.036 0.022 0.020 0.015 0.015 0.053 0.017 0.037 0.016 0.016 0.018

a

Data are means of 8 observations per treatment except for the diet with 150 g/kg sugar beet pulp where only 7 observations were used. DM = dry matter; OM = organic matter; CP = crude protein; AEE = acid hydrolyzed ether extract; NDF = neutral detergent fiber; ADF = acid detergent fiber; TDF = total dietary fiber; IDF = insoluble dietary fiber; SDF = soluble dietary fiber; Ins. Hemi = insoluble hemicelluloses; NSP = non-starch polysaccharides; Ins. NSP = insoluble non-starch polysaccharides; NC NSP = non-cellulosic non-starch polysaccharides. c CS = corn starch diet. d Linear reduction (P < 0.05) for inclusion of 150 or 300 g/kg canola meal, corn germ meal, sugar beet pulp, or wheat middlings. e Linear increase (P < 0.05) for canola meal or wheat middlings but linear reduction (P < 0.001) for corn germ meal or sugar beet pulp with inclusion of 150 or 300 g/kg of ingredient. f Linear reduction (P < 0.001) for canola meal or wheat middlings but linear increase (P < 0.05) for corn germ meal or sugar beet pulp with inclusion of 150 or 300 g/kg of ingredient. g Linear reduction (P < 0.001) for canola meal or wheat middlings but linear increase (P < 0.001) for sugar beet pulp with inclusion of 150 or 300 g/kg of ingredient. h Linear reduction (P < 0.05) for canola meal but linear increase (P < 0.001) for sugar beet pulp with inclusion of 150 or 300 g/kg of ingredient. i Linear increase (P < 0.001) for inclusion of 150 or 300 g/kg of corn germ meal. j Linear increase (P < 0.001) for sugar beet pulp but linear reduction (P < 0.001) for wheat middlings with inclusion of 150 or 300 g/kg of ingredient. k Linear increase (P < 0.001) for canola meal or sugar beet pulp but linear reduction (P < 0.05) for wheat middlings with inclusion of 150 or 300 g/kg of ingredient. b

Table 9 Coefficient of total tract apparent digestibility of dry matter and nutrients in ingredients at 150 or 300 g/kg inclusion ratea. Itemb

Canola meal 150

DM OM CP AEE NDF ADF TDF IDF SDF Cellulose Ins. Hemi. NSP Ins. NSP NC NSP

0.694 0.732 0.790 0.617 0.361 0.288 0.558 0.566 0.212 0.481 0.543 0.725 0.741 0.937

300 0.715 0.757 0.824 0.641 0.400 0.292 0.549 0.553 0.492 0.506 0.692 0.738 0.756 0.957

Corn germ meal SEM 0.038 0.036 0.031 0.110 0.041 0.035 0.050 0.047 0.248 0.034 0.109 0.063 0.059 0.100

150 0.719 0.750 0.644 −0.690 0.743 0.682 0.722 0.735 0.444 0.771 0.781 0.755 0.770 0.748

300 0.824 0.847 0.612 0.042 0.760 0.706 0.770 0.757 0.916 0.759 0.793 0.793 0.781 0.808

Sugar beet pulp SEM *

0.029 0.025* 0.047 0.187* 0.032 0.036 0.028 0.028 0.084* 0.031 0.048 0.038 0.037 0.047

Wheat middlings

150

300

SEM

150

300

SEM

0.786 0.815 0.260 −1.055 0.773 0.808 0.845 0.819 1.035 0.905 0.693 0.887 0.869 0.874

0.834 0.860 0.182 −0.825 0.794 0.833 0.883 0.862 0.995 0.910 0.708 0.914 0.900 0.919

0.033 0.035 0.201 0.121 0.034 0.023 0.020 0.024 0.023 0.024 0.065 0.021 0.025 0.024

0.701 0.735 0.716 0.448 0.466 0.032 0.510 0.529 −1.000 0.145 0.626 0.569 0.590 0.670

0.813 0.836 0.760 0.608 0.511 0.165 0.575 0.574 0.633 0.261 0.642 0.624 0.625 0.705

0.032* 0.032* 0.076 0.162 0.041 0.055* 0.034 0.033 0.325* 0.062 0.041 0.036 0.035 0.032

* 150 g/kg and 300 g/kg values differ (P < 0.05). a Data are means of 8 observations per treatment except for the diet with 150 g/kg sugar beet pulp where only 7 observations were used. b DM = dry matter; OM = organic matter; CP = crude protein; AEE = acid hydrolyzed ether extract; NDF = neutral detergent fiber; ADF = acid detergent fiber; TDF = total dietary fiber; IDF = insoluble dietary fiber; SDF = soluble dietary fiber; Ins. Hemi = insoluble hemicelluloses; NSP = non-starch polysaccharides; Ins. NSP = insoluble non-starch polysaccharides; NC NSP = non-cellulosic non-starch polysaccharides. 7

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(P < 0.05) with inclusion of canola meal in the diet, but increased (linear, P < 0.05) with addition of sugar beet pulp. Addition of wheat middlings decreased (linear, P < 0.05) the CTTAD of ADF, TDF, IDF, and cellulose. Addition of corn germ meal to the corn starch diet increased (linear, P < 0.05) the CTTAD of insoluble hemicelluloses and addition of canola meal increased (linear, P < 0.05) the CTTAD of non-cellulosic NSP. The CTTAD of NSP, insoluble NSP, and non-cellulosic NSP was increased (linear, P < 0.05) by inclusion of sugar beet pulp, but decreased (linear, P < 0.05) with addition of wheat middlings to the corn starch diet. The CTTAD of DM, OM, AEE, and SDF in corn germ meal increased (P < 0.05) if 300 g/kg rather than 150 g/kg was included in the diet (Table 9) and the CTTAD of DM, OM, ADF, and SDF in wheat middlings increased (P < 0.05) as inclusion level increased from 150 to 300 g/kg. However, no differences in CTTAD of DM and nutrients in canola meal and sugar beet pulp were observed between 150 and 300 g/kg inclusion rate. 4. Discussion The CTTAD of NDF and ADF in canola meal was less than values obtained by Maison et al. (2015), but differences in CTTAD of NDF and ADF among sources of canola meal were observed and attributed to differences among varieties or growing conditions that may have affected the chemical composition of the seeds (Maison et al., 2015). It is also possible that differences among crushing plants in processing procedures used may affect nutrient digestibility. The CIAD and CTTAD of DM and NDF in corn germ meal was slightly greater than reported data (Gutierrez et al., 2014). The CTTAD of DM, OM, and CP in wheat middlings was in agreement with values reported by Huang et al. (2013), and the CIAD and CTTAD of DM and most nutrients in wheat middlings were close to values reported by Jaworski and Stein (2017). Low or negative values for CHAD and CTTAD of AEE were observed due to low concentrations of AEE in the diets and the synthesis of endogenous microbial lipids in the hindgut, which contribute to increased endogenous losses of AEE (Gutierrez et al., 2016). Dietary fiber also may impede micelle formation and directly inhibit lipolytic activity, which may contribute to the reduction in CIAD of AEE (Schneeman and Gallaher, 2001). The observation that there were no differences for the CTTAD of DM or OM in canola meal and sugar beet pulp between inclusion rates indicate that the hindgut microbes were not overwhelmed by the increased quantities of fiber entering the hindgut at 300 g/kg inclusion rate. The CTTAD of CP was not different between inclusion levels of canola meal, corn germ meal, sugar beet pulp, and wheat middlings, which is in agreement with values for wheat middlings reported by Huang et al. (2013). Increasing the inclusion rate of soybean meal resulted in greater CTTAD of CP and fiber in the diet, but a decrease in CTTAD of gross energy in the diet when fed to growing pigs (Huang et al., 2013), which may be due to increased concentration of digestible protein and the replacement of starch with protein and fiber. This indicates that digestibility of some nutrients may be dependent on inclusion rate of the test ingredient in the diet and the extent of reduction in digestibility depends on the type of fiber source that is used (Le Gall et al., 2009). The reason inclusion of test ingredients in the corn starch diet reduced CIAD and CTTAD of DM, OM, and CP is that increased dietary fiber usually reduces the CTTAD of gross energy and CP (Yin et al., 2000; Le Goff and Noblet, 2001; Le Goff et al., 2002; Owusu-Asiedu et al., 2006; Le Gall et al., 2009). The reduction in digestibility of DM and nutrients is a result of a decrease in transit time in the hindgut, resulting in less time for microbial fermentation of digesta (Morel et al., 2006; Wilfart et al., 2007). However, transit time likely had no effect on digestibility because there were no differences in the time it took for digesta to first appear at the end of the ileum and in the feces between experimental diets (Navarro et al., 2018b). Therefore, the reduction in CIAD of CP and AEE in canola meal, when the inclusion rate increased from 150 to 300 g/kg, may be a result of impaired rate of nutrient absorption due to increased concentration of mucin in the unstirred water layer, which is a consequence of increased fiber intake (Montagne et al., 2004). The CHAD of IDF, cellulose, insoluble hemicelluloses, NSP, insoluble NSP, and non-cellulosic NSP was generally greater than the CIAD of these fiber fractions in both diets and ingredients, which indicates that fermentation of fiber occurs mainly in the hindgut of the pig. Sugar beet pulp fiber is more easily fermented in the gastrointestinal tract of the pig as indicated by greater CTTAD of most of its fiber fractions compared with the other ingredients. Furthermore, the increase in CHAD of DM, OM, and CP in diets is due to the greater flow of these nutrients into the hindgut due to a decrease in their digestibility in the upper gut. The negative values for the CIAD of SDF in canola meal, corn germ meal, sugar beet pulp, and wheat middlings are a result of more SDF being analyzed at the end of the ileum than in the diet, which is likely due to endogenous mucin secretion or microbial matter that may be analyzed as carbohydrates (Cervantes-Pahm et al., 2014). A major source of the nondietary interfering material in the SDF fraction of ileal digesta is mucin, whereas microbial matter represents 990 g/kg of nondietary interfering material in the IDF fraction of both ileal digesta and feces (Montoya et al., 2015). Mucin contains N-acetylgalactosamine, N-acetylglucosamine, galactose, fucose, sialic acids, and mannose attached to the protein core, some of which are monosaccharides that are also present in dietary fiber (Bansil and Turner, 2006). Consequently, calculated values for CIAD of TDF is expected to underestimate the actual CIAD because TDF is the sum of IDF and SDF. It was unexpected that the calculated CTTAD of IDF was greater than the CTTAD of SDF in diets, but this was likely due to the greater proportion of endogenous sources of carbohydrates analyzed as SDF relative to the concentration of SDF in the diet compared with endogenous IDF relative to the concentration of IDF in the diet. However, the calculated CHAD of SDF was greater than 1.0 for most diets and was greater than the CHAD of IDF indicating that SDF is more fermentable than IDF (Urriola et al., 2010). High digestibility of IDF has been reported (Jaworski and Stein, 2017; Navarro et al., 2018a), and indicates that a fraction of analyzed IDF is solubilized along the gastrointestinal tract. The CIAD of IDF was 0.352 in the diet containing 300 g/kg wheat middlings, indicating that a significant amount of IDF was solubilized in the small intestine and may have been analyzed as SDF in the ileal digesta, which may also have contributed to the negative values that were calculated for CIAD of SDF in experimental diets. 8

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Solubilization of IDF may not necessarily indicate that IDF is digested and absorbed in the small intestine, but it indicates that the fiber structure may have been altered and subsequently analyzed as SDF. However, to our knowledge, this has never previously been reported and needs to be further investigated. It is possible that the analytical procedures used may have influenced results because current analytical methods were developed to determine fiber in food and feedstuff and not in ileal digesta or feces (Montoya et al., 2016), which may explain the high CIAD and CTTAD of IDF in this experiment. In conclusion, fiber may have a negative effect on the digestibility of DM and nutrients in the diet, the extent to which is dependent on the concentration and the source of fiber. Inclusion of high fiber dietary ingredients in the diet increases the flow of DM and nutrients into the hindgut of the pig, resulting in greater fermentation of these nutrients. Although there is degradation of some fiber fractions before the end of the small intestine, the majority of fermentation takes place in the hindgut. The CIAD, CHAD, and CTTAD of most nutrients measured at 150 g/kg inclusion is not different when measured at 300 g/kg inclusion of test ingredients, indicating that the inclusion rate of high fiber dietary ingredients does not influence the digestibility of most nutrients. There was a high digestibility of IDF under the conditions of this experiment, which indicates that digestibility of fiber may have traditionally been underestimated. However, current methods for determination of fiber fractions were developed for food and feedstuff and it is not known if they are also applicable to ileal digesta and fecal samples. Acknowledgement Financial support from Agrifirm Innovation Center, Apeldoorn, The Netherlands, is greatly appreciated. References Adeola, O., 2001. Digestion and balance techniques in pigs. In: Lewis, A.J., Southern, L.L. (Eds.), Swine Nutrition, 2nd ed. CRC Press, New York, NY, pp. 903–916. AOAC International, 2007. Official methods of analysis of AOAC International. Rev. 2. Association of Official Analytical Chemist, Gaithersburg, MD, 18th ed. . Bansil, R., Turner, B.S., 2006. Mucin structure, aggregation, physiological functions and biomedical applications. Curr. Opin. Colloid Interface Sci. 11, 164–170. https://doi.org/10.1016/j.cocis.2005.11.001. Cervantes-Pahm, S.K., Liu, Y., Evans, A., Stein, H.H., 2014. Effect of novel fiber ingredients on ileal and total tract digestibility of energy and nutrients in semi-purified diets fed to growing pigs. J. Sci. Food Agric. 94, 1284–1290. https://doi.org/10.1002/jsfa.6405. Gutierrez, N.A., Serão, N.V.L., Kerr, B.J., Zijlstra, R.T., Patience, J.F., 2014. Relationships among dietary fiber components and the digestibility of energy, dietary fiber, and amino acids and energy content of nine corn coproducts fed to growing pigs. J. Anim. Sci. 92, 4505–4517. https://doi.org/10.2527/jas.2013-7265. Gutierrez, N.A., Serão, N.V.L., Patience, J.F., 2016. Effects of distillers’ dried grains with solubles and soybean oil on dietary lipid, fiber, and amino acid digestibility in corn-based diets fed to growing pigs. J. Anim. Sci. 94, 1508–1519. https://doi.org/10.2527/jas.2015-9529. Huang, Q., Piao, X., Liu, L., Li, D., 2013. Effects of inclusion level on nutrient digestibility and energy content of wheat middlings and soya bean meal for growing pigs. Arch. Anim. Nutr. 67, 356–367. https://doi.org/10.1080/1745039X.2013.837233. Jaworski, N.W., Stein, H.H., 2017. Disappearance of nutrients and energy in the stomach and small intestine, cecum, and colon of pigs fed corn-soybean meal diets containing distillers dried grains with solubles, wheat middlings, or soybean hulls. J. Anim. Sci. 95, 727–739. https://doi.org/10.2527/jas.2016.0752. Le Gall, M., Warpechowski, M., Jaguelin-Peyraud, Y., Noblet, J., 2009. Influence of dietary fibre level and pelleting on the digestibility of energy and nutrients in growing pigs and adult sows. Animal 3, 352–359. https://doi.org/10.1017/S1751731108003728. Le Goff, G., Noblet, J., 2001. Comparative total tract digestibility of dietary energy and nutrients in growing pigs and adult sows. J. Anim. Sci. 79, 2418–2427. https:// doi.org/10.2527/2001.7992418x. Le Goff, G., van Milgen, J., Noblet, J., 2002. Influence of dietary fibre on digestive utilization and rate of passage in growing pigs, finishing pigs and adult sows. Anim. Sci. 74, 503–515. https://doi.org/10.1017/S1357729800052668. Maison, T., Liu, Y., Stein, H.H., 2015. Digestibility of energy and detergent fiber and digestible and metabolizable energy values in canola meal, 00-rapeseed meal, and 00-rapeseed expellers fed to growing pigs. J. Anim. Sci. 93, 652–660. https://doi.org/10.2527/jas.2014-7792. Montagne, L., Piel, C., Lallès, J.P., 2004. Effect of diet on mucin kinetics and composition: nutrition and health implications. Nutr. Rev. 62, 105–114. https://doi.org/ 10.1111/j.1753-4887.2004.tb00031.x. Montoya, C.A., Rutherfurd, S.M., Moughan, P.J., 2015. Nondietary gut materials interfere with the determination of dietary fiber digestibility in growing pigs when using the prosky method. J. Nutr. 145, 1966–1972. https://doi.org/10.3945/jn.115.212639. Montoya, C.A., Henare, S.J., Rutherfurd, S.M., Moughan, P.J., 2016. Potential misinterpretation of the nutritional value of dietary fiber: correcting fiber digestibility values for nondietary gut-interfering material. Nutr. Rev. 74, 517–533. https://doi.org/10.1093/nutrit/nuw014. Morel, P.C.H., Lee, T.S., Moughan, P.J., 2006. Effect of feeding level, live weight and genotype on the apparent faecal digestibility of energy and organic matter in the growing pig. Anim. Feed Sci. Technol. 126, 63–74. https://doi.org/10.1016/j.anifeedsci.2005.06.006. Myers, W.D., Ludden, P.A., Nayigihugu, V., Hess, B.W., 2004. Technical note: a procedure for the preparation and quantitative analysis of samples for titanium dioxide. J. Anim. Sci. 82, 179–183. https://doi.org/10.2527/2004.821179x. Navarro, D.M.D.L., Bruininx, E.M.A.M., de Jong, L., Stein, H.H., 2018a. Effects of physicochemical characteristics of feed ingredients on the apparent total tract digestibility of energy, dry matter and nutrients by growing pigs. J. Anim. Sci. 96, 2265–2277. https://doi.org/10.1093/jas/sky149. Navarro, D.M.D.L., Bruininx, E.M.A.M., de Jong, L., Stein, H.H., 2018b. The contribution of digestible and metabolizable energy in high fiber dietary ingredients is not affected by inclusion rate in mixed diets fed to growing pigs. J. Anim. Sci. 96, 1860–1868. https://doi.org/10.1093/jas/sky090. Owusu-Asiedu, A., Patience, J.F., Laarveld, B., van Kessel, A.G., Simmins, P.H., Zijlstra, R.T., 2006. Effects of guar gum and cellulose on digesta passage rate, ileal microbial populations, energy and protein digestibility, and performance of grower pigs. J. Anim. Sci. 84, 843–852. https://doi.org/10.2527/2006.844843x. Schneeman, B.O., Gallaher, D., 2001. Effects of dietary fiber on digestive enzymes. In: Spiller, G.A. (Ed.), CRC Handbook of Dietary Fiber in Human Nutrition, 3rd ed. CRC Press, Boca Raton, FL, pp. 277–286. Stein, H.H., Sève, B., Fuller, M.F., Moughan, P.J., de Lange, C.F.M., 2007. Invited review: amino acid bioavailability and digestibility in pig feed ingredients: terminology and application. J. Anim. Sci. 85, 172–180. https://doi.org/10.2527/jas.2005-742. Urriola, P.E., Shurson, G.C., Stein, H.H., 2010. Digestibility of dietary fiber in distillers coproducts fed to growing pigs. J. Anim. Sci. 88, 2373–2381. https://doi.org/ 10.2527/jas.2009-2227. Urriola, P.E., Cervantes-Pahm, S.K., Stein, H.H., 2013. Fiber in swine nutrition. In: Chiba, L.I. (Ed.), Sustainable Swine Nutrition. John Wiley & Sons, Inc, Ames, IA, pp. 255–276. https://doi.org/10.1002/9781118491454.ch11. Widmer, M.R., McGinnis, L.M., Stein, H.H., 2007. Energy, phosphorus, and amino acid digestibility of high-protein distillers grains and corn germ fed to growing pigs. J. Anim. Sci. 85, 2994–3003. https://doi.org/10.2527/jas.2006-840. Wilfart, A., Montagne, L., Simmins, H., Noblet, J., van Milgen, J., 2007. Digesta transit in different segments of the gastrointestinal tract of pigs as affected by insoluble fibre supplied by wheat bran. Br. J. Nutr. 98, 54–62. https://doi.org/10.1017/S0007114507682981. Yin, Y.-L., McEvoy, J.D.G., Schulze, H., Hennig, U., Souffrant, W.-B., McCracken, K.J., 2000. Apparent digestibility (ileal and overall) of nutrients and endogenous nitrogen losses in growing pigs fed wheat (var. Soissons) or its byproducts without or with xylanase supplementation. Livest. Prod. Sci. 62, 119–132. https://doi. org/10.1016/S0301-6226(99)00129-3.

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