Standardized ileal digestibility of amino acids in alfalfa meal, sugar beet pulp, and wheat bran compared to wheat and protein ingredients for growing pigs1 M. Eklund,*2 M. Rademacher,† W. C. Sauer,‡ R. Blank,§ and R. Mosenthin* *Institute of Animal Nutrition, University of Hohenheim, 70593 Stuttgart, Germany; †Evonik Industries AG, Health & Nutrition, 63457 Hanau-Wolfgang, Germany; ‡Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada, T6G 2P5; and §Institute of Animal Nutrition and Physiology, University of Kiel, 24098 Kiel, Germany
ABSTRACT: A total of 11 (8 + 3 for replacement) barrows with an initial BW of 23 kg and fitted with a simple T-cannula at the distal ileum were used in 2 consecutive experiments (Exp. 1 and Exp. 2) to determine the standardized ileal digestibility (SID) of AA in 7 assay feed ingredients according to 2 consecutive duplicated 4 × 4 Latin square designs. In Exp. 1, 3 corn starch-based assay diets were formulated to contain 170 g CP/kg (as-fed basis) from either soybean meal (SBM), canola meal (CM), or meat-and-bone meal (MBM) and 1 assay diet that contained 136 g CP/kg (as-fed basis) from wheat as commonly used feed ingredients for pigs. In Exp. 2, the pigs were fed 4 assay diets formulated to contain 170 g CP/kg (as-fed basis) from either the same SBM as in Exp. 1 or a combination of this SBM and alfalfa meal (AM), sugar beet pulp (SB), or wheat bran (WB)
to compare the SID of AA in these feed ingredients with those used in Exp. 1. The SID of AA in CM was lower compared to SBM (P < 0.05) with intermediate values for MBM and wheat. Among fiber rich feed ingredients, SID values were lower in SB compared to WB (P < 0.05) with intermediate values for AM. In AM, SID values ranged between 29 and 45% for Lys, Cys, Thr, and Phe and between 51 and 71% for Arg, His, Ile, Leu, Met, and Val. In SB, SID values ranged between –21 and 46% for Cys, Thr, Phe, and Val and between 51 and 61% for Arg, His, Ile, Leu, Lys, and Met. In WB, SID values were between 55 and 64% for Lys, Cys, Phe, Thr, and Val and between 68 and 80% for Arg, His, Ile, Leu, and Met. The SID values in WB, SB, and AM provided in the present study may improve diet formulation when these feed ingredients are used in diet formulation for pigs.
Key words: amino acids, digestibility, ileum, pig © 2014 American Society of Animal Science. All rights reserved. J. Anim. Sci. 2014.92:1037–1043 doi:10.2527/jas2013-6436 INTRODUCTION There is abundant information on standardized ileal digestibility (SID) of AA in commonly used feed ingredients such as cereal grains, oil seed meals, or animal proteins (e.g., NRC, 1998; GfE, 2008; Evonik, 2010). However, to our knowledge, there are no reports in peerreviewed journals on SID of AA in alfalfa meal (AM), wheat bran (WB), or sugar beet pulp (SB). These feed ingredients may have economical advantages in least 1The authors are indebted to Brenda Tchir and Charlane Gorsak for their assistance with surgery and postoperative care. Financial support was provided by the H. Wilhelm Schaumann Foundation, Hamburg, Germany, and the Natural Sciences and Engineering Research Council (NSERC), Canada. 2Corresponding author: [email protected] Received March 4, 2013. Accepted December 28, 2013.
cost diet formulation for pigs. Alfalfa meal, WB, and SB and may contain 200, 160, and 90 g CP/kg (as-fed basis), respectively (NRC, 1998). Their use as protein and energy source in pig diets, however, is limited due to high fiber contents amounting to an average of about for 420 g NDF/kg in AM, WB, and SB and to 280, 240, and 130 g ADF/kg (as-fed basis) in AM, WB, and SB, respectively (NRC, 1998). Dietary fiber has been classified as antinutrient due to its detrimental effect on SID of AA (Ma et al., 2008), mainly because fiber may structurally link a portion of the CP (Bach Knudsen, 2001), thereby interfering with protein digestion or may increase endogenous AA secretion (De Lange et al., 1989). The present study with pigs was designed to determine for the first time SID of AA in AM, SB, and WB and to compare these SID values with those in wheat and commonly used protein ingredients including soy-
1037 Downloaded from https://academic.oup.com/jas/article-abstract/92/3/1037/4702211 by Universiteitsbibliotheek Utrecht user on 25 April 2018
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bean meal (SBM), canola meal (CM), and meat-andbone meal (MBM).
Table 1. Chemical composition (g/kg, as-fed basis) of the assay feed ingredients
MATERIALS AND METHODS Animals and Housing The animal protocol was approved by the University of Alberta Animal Care and Use Committee for Livestock and followed principles established by the Canadian Council on Animal Care (1993). Two consecutive experiments (Exp. 1 and Exp. 2) were conducted with a total of 11 (8 + 3 for replacement) PIC (Pig Improvement Canada) barrows (Camborough × Canabrid), with an average initial and final BW of 23 ± 2 and 59 ± 4 kg, respectively. The pigs were obtained from the University of Alberta swine herd and were kept in stainless steel metabolism cages. The temperature in the research unit was maintained at 20 to 22°C. Each cage was equipped with a low-pressure drinking nipple. Surgical Procedure The pigs were fitted with a simple T-cannula at the distal ileum according to procedures described by Sauer et al. (1983). The cannulas were modified according to De Lange et al. (1989). A detailed description of the pre- and postoperative care was given by Li et al. (1993). During the first 24 h after surgery, the temperature within the cages was maintained at 30 to 32°C using overhead infrared heating lamps. Throughout the postsurgical recuperation period, the daily feed allowance was gradually increased until all pigs consumed daily 50 g feed (as-fed basis) per kilogram of their average BW. Dietary Treatments and Experimental Design A total of 7 assay diets was formulated. In Exp. 1, pigs were fed a diet containing either 933 g W/kg (as-fed basis) or 1 of 3 corn starch–based assay diets formulated to contain 170 g CP/kg (as-fed basis) from SBM, CM, or MBM (Tables 1, 2, and 3). In Exp. 2, pigs were fed either the corn starch–based SBM diet from Exp. 1 or 1 of 3 assay diets that contained 170 g CP/kg (as-fed basis) from combinations of the same SBM that was used in Exp. 1 with AM, SB, or WB (Tables 1, 2, and 3). Dextrose was included at a level of 100 g/kg (as-fed basis) in all assay diets except for the wheat assay diet to improve the palatability. All assay diets contained 30 g canola oil/kg (asfed basis) to reduce the dustiness of the diets. Vitamins and minerals were supplemented to meet or exceed NRC (1998) standards. Chromic oxide was included in the assay diets at a level of 3 g/kg (as-fed basis) as a digestibility marker. The assay feed ingredients were ground through Downloaded from https://academic.oup.com/jas/article-abstract/92/3/1037/4702211 by Universiteitsbibliotheek Utrecht user on 25 April 2018
Exp.: DM CP Arg His Ile Leu Lys Met Cys Phe Thr Val
SBM 1 and 2 880 477 26.8 9.9 19.1 27.8 32.9 6.9 7.0 15.8 16.1 19.4
Assay feed ingredients1 CM MBM Wheat AM 1 1 1 2 914 938 871 920 353 510 143 177 13.7 25.8 5.9 6.4 11.9 7.7 3.2 2.6 12.9 11.3 5.1 6.8 19.7 23.6 9.1 9.8 22.8 31.7 3.7 6.8 7.7 7.6 2.4 2.9 9.3 4.8 3.4 1.8 9.8 11.2 5.4 6.3 9.6 14.0 4.3 6.4 16.0 16.1 6.0 7.8
SB 2 914 103 3.3 2.5 3.7 5.5 6.5 1.2 1.0 2.9 3.9 4.9
WB 2 899 145 7.4 3.5 4.6 8.1 5.2 2.4 3.6 4.7 4.4 6.0
1SBM = soybean meal; CM = canola meal; MBM = meat-and-bone meal; AM = alfalfa meal; SB = sugar beet pulp; WB = wheat bran.
a 3.2-mm-mesh screen before incorporation into the assay diets. Both experiments were conducted according to duplicated 4 × 4 Latin square designs. In each experiment, the experimental animals were randomly allocated to the assay diets. The assay diets were fed at 0800 and 2000 h at a daily feed intake level of 50 g (as-fed basis)/ kg of the animals’ average BW. The BW of each animal was determined at the beginning of each experimental period. Each experimental period comprised 10 d. Ileal digesta was collected continuously for 24 h from 0800 to 2000 h on d 9 and from 2000 h on d 10 to 0800 h on d 11. The procedures for digesta collection were described previously by Li et al. (1993), using plastic bags attached to the barrel of the cannula with elastic bands. The bags were changed at least every 30 min, and the content was immediately frozen at –20°C. During collection, 5 mL of 10% formic acid were added to the sampling bags to minimize bacterial fermentation. Analytical and Statistical Procedures Samples of the assay diets were taken each time the feed allowances were weighed and pooled for each dietary treatment. Digesta samples were freeze-dried, pooled within pig and period for the same dietary treatment, and ground in a Wiley mill (Arthur H. Thomas Co, Philadelphia, PA) through a 0.8-mm-mesh screen and mixed before analyses. The samples of the assay diets and assay feed ingredients were ground correspondingly. In the assay feed ingredients, assay diets, and digesta samples, analysis of DM was performed according to the AOAC International (2000) and N was determined with a LECO FP-428 N Analyzer (LECO Corporation,
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Table 2. Formulation (g/kg) of the assay diets
Table 3. Chemical composition (g/kg, as-fed basis) of the assay diets
diets1
SBM Exp.: 1 and 2 Soybean meal 378 Canola meal – Meat-and-bone meal – Wheat – Alfalfa meal – Sugar beet pulp – Wheat bran – Corn starch 454 Dextrose 100 Canola oil 30 Iodized salt 5 Calcium carbonate 8 Dicalcium phosphate 12 Vitamin and mineral premix2 10 Cr2O3 3
Assay CM MBM Wheat 1 1 1 – 460 – – – 317 – – – 933 – – – – – – – – 384 535 – 100 100 – 30 30 30 5 5 5 8 – 12 – – 7 10 10 10 3 3 3
AM 2 189 – – – 443 – – 207 100 30 5 – 13 10 3
SB 2 236 – – – – 602 – – 100 30 5 – 14 10 3
WB 2 236 – – – – – 414 189 100 30 5 13 – 10 3
1SBM = soybean meal; CM = canola meal; MBM = meat-and-bone meal; AM = alfalfa meal; SB = sugar beet pulp; WB = wheat bran. 2The vitamin and mineral premix provided the following per kilogram of diet: 5,000 IU vitamin A, 500 IU vitamin D3, 40 IU vitamin E, 2 mg vitamin K3, 30 µg vitamin B12, 12 mg riboflavin, 40 mg niacin, 25 mg pantothenic acid, 300 mg choline, 1,600 mg folic acid, 150 mg Fe, 100 mg Zn, 12 mg Mn, 20 mg Cu, 0.2 mg I, and 0.3 mg Se.
St. Joseph, MI). Chromic oxide was determined according to Fenton and Fenton (1979). For AA analyses, approximately 0.1 g of sample was weighed into a screwcapped tube and mixed with 3 mL of 6 N HCl. The tubes were purged with N and then hydrolyzed in an oven at 110°C for 24 h. The hydrolyzed samples were mixed with the internal standard, dl-amino-n-butyric acid, and centrifuged at 2,100 × g for 15 min at room temperature. The supernatant of the samples was analyzed according to the method of Jones and Gilligan (1983) using a Varian high performance liquid chromatography system (model 5000; Varian Associates, Sunnyvale, CA). A reverse-phase column was used following the procedures previously described by Dugan et al. (1989). The AA in the samples was derivatized with an o-phthaldialdehyde reagent solution and detected spectrofluorometrically. Methionine and Cys were determined as methionine sulfone and cysteic acid, respectively, after oxidation with 98% performic acid according to the AOAC International (2000). The oxidized samples were dried according to the procedure described by Dugan et al. (1992) and then hydrolyzed in the same manner as the samples that were not oxidized. Analyses of feed ingredients and diets were performed in triplicate and analyses of digesta in duplicate. The apparent ileal digestibility (AID) of AA in the assay diets was calculated using Cr2O3 as an indigestible marker as described by (Eklund et al., 2012).
Downloaded from https://academic.oup.com/jas/article-abstract/92/3/1037/4702211 by Universiteitsbibliotheek Utrecht user on 25 April 2018
Exp.: DM CP Arg His Ile Leu Lys Met Cys Phe Thr Val
SBM 1 and 2 899 177 15.9 6.1 9.7 17.4 12.5 2.4 2.6 9.8 9.3 10.2
Assay diets1 CM MBM Wheat AM 1 1 1 2 913 917 891 924 156 155 136 169 8.9 10.1 5.9 8.1 4.5 3.0 3.2 3.7 6.2 4.5 4.7 6.5 10.6 9.6 8.7 10.7 10.3 9.8 3.7 9.3 3.2 2.2 2.3 2.1 3.8 1.4 3.2 2.3 5.4 4.6 5.6 6.2 7.2 5.4 4.3 6.0 7.7 6.5 5.5 7.2
SB 2 924 172 9.0 4.3 6.8 10.9 9.8 2.1 2.0 6.2 6.2 7.7
WB 2 910 161 9.8 4.3 6.4 10.6 8.7 2.0 2.7 6.2 5.6 7.1
1SBM = soybean meal; CM = canola meal; MBM = meat-and-bone meal; AM = alfalfa meal; SB = sugar beet pulp; WB = wheat bran.
The SID of AA in the assay diets was calculated by correcting AID of AA for basal ileal endogenous AA loss (IAAend), expressed as grams per kilogram DMI. The IAAend was obtained from a literature review by Jansman et al. (2002). The SID of AA in the assay diets were calculated according to the following equation: SIDD = AIDD + (IAAend/AD) × 100%, in which SIDD = SID of AA in the assay diets (%), AIDD = AID of AA in the assay diets (%), IAAend = basal ileal endogenous loss of AA (g/kg DMI), and AD = AA content in the assay diets (g/kg DMI). The SID of AA originating from AM, SB, or WB in Exp. 2 was calculated according to the following equation: SIDA = (SIDD – SIDB × CB)/CA, in which CB is the contribution level of AA from SBM to the assay diet (%) and CA is the contribution level of AA from the assay feed ingredient to the assay diet (%). Data were analyzed by ANOVA using the PROC MIXED of SAS (SAS Inst. Inc., Cary, NC). Fixed effects included animals and assay diets. Periods and animals within experiments were considered as random effects assuming a compound symmetry variance-covariance structure. A probability level of P < 0.05 was defined as significant difference. Significant differences between treatments were represented by different superscript letters using the algorithm for letter-based representation of all pairwise comparisons according to Piepho (2004).
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Table 4. Standardized ileal digestibility of AA (%) in the assay feed ingredients1
Exp.: n: Arg His Ile Leu Lys Met Cys Phe Thr Val
SBM
CM
MBM
Wheat
AM
SB
WB
P-value
1 and 2 16 (8 + 8) 96 ± 1.5d 95 ± 1.3c 93 ± 1.4d 93 ± 1.3e 92 ± 1.5f 92 ± 1.0e 85 ± 3.2d 92 ± 1.5e 91 ± 2.1f 94 ± 1.4e
1 8 84 ± 2.2c 82 ± 2.0b 72 ± 2.1b 76 ± 2.0c 77 ± 2.3d 79 ± 1.5c 67 ± 4.9c 75 ± 2.2c 69 ± 3.2d 73 ± 2.1c
1 7 88 ± 2.0c 85 ± 1.9b 84 ± 1.9c 84 ± 1.9d 86 ± 2.1e 85 ± 1.4d 60 ± 4.6c 84 ± 2.1d 79 ± 3.0e 85 ± 2.0d
1 8 84 ± 2.0c 86 ± 1.9b 85 ± 1.9c 85 ± 1.9d 68 ± 2.1c 84 ± 1.4d 86 ± 5.4d 93 ± 2.1e 77 ± 3.0ed 84 ± 2.0d
2 6 59 ± 2.4a 51 ± 2.2a 54 ± 2.3a 53 ± 2.2a 31 ± 2.4a 71 ± 1.7b 29 ± 5.3b 48 ± 2.4a 41 ± 3.5b 52 ± 2.3b
2 6 54 ± 2.4a 52 ± 2.2a 53 ± 2.3a 51 ± 2.2a 56 ± 2.4b 61 ± 1.7a –21 ± 5.3a 46 ± 2.4a 30 ± 3.5a 43 ± 2.3a
2 6 76 ± 2.4b 80 ± 2.2b 68 ± 2.3b 68 ± 2.2b 62 ± 2.4cb 69 ± 1.7b 63 ± 5.4c 64 ± 2.4b 55 ± 3.5c 67 ± 2.3c
ABSTRACT: A total of 11 (8 + 3 for replacement) barrows with an initial BW of 23 kg and fitted with a simple T-cannula at the distal ileum were used in 2 consecutive experiments (Exp. 1 and Exp. 2) to determine the standardized ileal digestibility (SID) of AA in 7 assay feed ingredients according to 2 consecutive duplicated 4 × 4 Latin square designs. In Exp. 1, 3 corn starch-based assay diets were formulated to contain 170 g CP/kg (as-fed basis) from either soybean meal (SBM), canola meal (CM), or meat-and-bone meal (MBM) and 1 assay diet that contained 136 g CP/kg (as-fed basis) from wheat as commonly used feed ingredients for pigs. In Exp. 2, the pigs were fed 4 assay diets formulated to contain 170 g CP/kg (as-fed basis) from either the same SBM as in Exp. 1 or a combination of this SBM and alfalfa meal (AM), sugar beet pulp (SB), or wheat bran (WB)
to compare the SID of AA in these feed ingredients with those used in Exp. 1. The SID of AA in CM was lower compared to SBM (P < 0.05) with intermediate values for MBM and wheat. Among fiber rich feed ingredients, SID values were lower in SB compared to WB (P < 0.05) with intermediate values for AM. In AM, SID values ranged between 29 and 45% for Lys, Cys, Thr, and Phe and between 51 and 71% for Arg, His, Ile, Leu, Met, and Val. In SB, SID values ranged between –21 and 46% for Cys, Thr, Phe, and Val and between 51 and 61% for Arg, His, Ile, Leu, Lys, and Met. In WB, SID values were between 55 and 64% for Lys, Cys, Phe, Thr, and Val and between 68 and 80% for Arg, His, Ile, Leu, and Met. The SID values in WB, SB, and AM provided in the present study may improve diet formulation when these feed ingredients are used in diet formulation for pigs.
Key words: amino acids, digestibility, ileum, pig © 2014 American Society of Animal Science. All rights reserved. J. Anim. Sci. 2014.92:1037–1043 doi:10.2527/jas2013-6436 INTRODUCTION There is abundant information on standardized ileal digestibility (SID) of AA in commonly used feed ingredients such as cereal grains, oil seed meals, or animal proteins (e.g., NRC, 1998; GfE, 2008; Evonik, 2010). However, to our knowledge, there are no reports in peerreviewed journals on SID of AA in alfalfa meal (AM), wheat bran (WB), or sugar beet pulp (SB). These feed ingredients may have economical advantages in least 1The authors are indebted to Brenda Tchir and Charlane Gorsak for their assistance with surgery and postoperative care. Financial support was provided by the H. Wilhelm Schaumann Foundation, Hamburg, Germany, and the Natural Sciences and Engineering Research Council (NSERC), Canada. 2Corresponding author: [email protected] Received March 4, 2013. Accepted December 28, 2013.
cost diet formulation for pigs. Alfalfa meal, WB, and SB and may contain 200, 160, and 90 g CP/kg (as-fed basis), respectively (NRC, 1998). Their use as protein and energy source in pig diets, however, is limited due to high fiber contents amounting to an average of about for 420 g NDF/kg in AM, WB, and SB and to 280, 240, and 130 g ADF/kg (as-fed basis) in AM, WB, and SB, respectively (NRC, 1998). Dietary fiber has been classified as antinutrient due to its detrimental effect on SID of AA (Ma et al., 2008), mainly because fiber may structurally link a portion of the CP (Bach Knudsen, 2001), thereby interfering with protein digestion or may increase endogenous AA secretion (De Lange et al., 1989). The present study with pigs was designed to determine for the first time SID of AA in AM, SB, and WB and to compare these SID values with those in wheat and commonly used protein ingredients including soy-
1037 Downloaded from https://academic.oup.com/jas/article-abstract/92/3/1037/4702211 by Universiteitsbibliotheek Utrecht user on 25 April 2018
1038
Eklund et al.
bean meal (SBM), canola meal (CM), and meat-andbone meal (MBM).
Table 1. Chemical composition (g/kg, as-fed basis) of the assay feed ingredients
MATERIALS AND METHODS Animals and Housing The animal protocol was approved by the University of Alberta Animal Care and Use Committee for Livestock and followed principles established by the Canadian Council on Animal Care (1993). Two consecutive experiments (Exp. 1 and Exp. 2) were conducted with a total of 11 (8 + 3 for replacement) PIC (Pig Improvement Canada) barrows (Camborough × Canabrid), with an average initial and final BW of 23 ± 2 and 59 ± 4 kg, respectively. The pigs were obtained from the University of Alberta swine herd and were kept in stainless steel metabolism cages. The temperature in the research unit was maintained at 20 to 22°C. Each cage was equipped with a low-pressure drinking nipple. Surgical Procedure The pigs were fitted with a simple T-cannula at the distal ileum according to procedures described by Sauer et al. (1983). The cannulas were modified according to De Lange et al. (1989). A detailed description of the pre- and postoperative care was given by Li et al. (1993). During the first 24 h after surgery, the temperature within the cages was maintained at 30 to 32°C using overhead infrared heating lamps. Throughout the postsurgical recuperation period, the daily feed allowance was gradually increased until all pigs consumed daily 50 g feed (as-fed basis) per kilogram of their average BW. Dietary Treatments and Experimental Design A total of 7 assay diets was formulated. In Exp. 1, pigs were fed a diet containing either 933 g W/kg (as-fed basis) or 1 of 3 corn starch–based assay diets formulated to contain 170 g CP/kg (as-fed basis) from SBM, CM, or MBM (Tables 1, 2, and 3). In Exp. 2, pigs were fed either the corn starch–based SBM diet from Exp. 1 or 1 of 3 assay diets that contained 170 g CP/kg (as-fed basis) from combinations of the same SBM that was used in Exp. 1 with AM, SB, or WB (Tables 1, 2, and 3). Dextrose was included at a level of 100 g/kg (as-fed basis) in all assay diets except for the wheat assay diet to improve the palatability. All assay diets contained 30 g canola oil/kg (asfed basis) to reduce the dustiness of the diets. Vitamins and minerals were supplemented to meet or exceed NRC (1998) standards. Chromic oxide was included in the assay diets at a level of 3 g/kg (as-fed basis) as a digestibility marker. The assay feed ingredients were ground through Downloaded from https://academic.oup.com/jas/article-abstract/92/3/1037/4702211 by Universiteitsbibliotheek Utrecht user on 25 April 2018
Exp.: DM CP Arg His Ile Leu Lys Met Cys Phe Thr Val
SBM 1 and 2 880 477 26.8 9.9 19.1 27.8 32.9 6.9 7.0 15.8 16.1 19.4
Assay feed ingredients1 CM MBM Wheat AM 1 1 1 2 914 938 871 920 353 510 143 177 13.7 25.8 5.9 6.4 11.9 7.7 3.2 2.6 12.9 11.3 5.1 6.8 19.7 23.6 9.1 9.8 22.8 31.7 3.7 6.8 7.7 7.6 2.4 2.9 9.3 4.8 3.4 1.8 9.8 11.2 5.4 6.3 9.6 14.0 4.3 6.4 16.0 16.1 6.0 7.8
SB 2 914 103 3.3 2.5 3.7 5.5 6.5 1.2 1.0 2.9 3.9 4.9
WB 2 899 145 7.4 3.5 4.6 8.1 5.2 2.4 3.6 4.7 4.4 6.0
1SBM = soybean meal; CM = canola meal; MBM = meat-and-bone meal; AM = alfalfa meal; SB = sugar beet pulp; WB = wheat bran.
a 3.2-mm-mesh screen before incorporation into the assay diets. Both experiments were conducted according to duplicated 4 × 4 Latin square designs. In each experiment, the experimental animals were randomly allocated to the assay diets. The assay diets were fed at 0800 and 2000 h at a daily feed intake level of 50 g (as-fed basis)/ kg of the animals’ average BW. The BW of each animal was determined at the beginning of each experimental period. Each experimental period comprised 10 d. Ileal digesta was collected continuously for 24 h from 0800 to 2000 h on d 9 and from 2000 h on d 10 to 0800 h on d 11. The procedures for digesta collection were described previously by Li et al. (1993), using plastic bags attached to the barrel of the cannula with elastic bands. The bags were changed at least every 30 min, and the content was immediately frozen at –20°C. During collection, 5 mL of 10% formic acid were added to the sampling bags to minimize bacterial fermentation. Analytical and Statistical Procedures Samples of the assay diets were taken each time the feed allowances were weighed and pooled for each dietary treatment. Digesta samples were freeze-dried, pooled within pig and period for the same dietary treatment, and ground in a Wiley mill (Arthur H. Thomas Co, Philadelphia, PA) through a 0.8-mm-mesh screen and mixed before analyses. The samples of the assay diets and assay feed ingredients were ground correspondingly. In the assay feed ingredients, assay diets, and digesta samples, analysis of DM was performed according to the AOAC International (2000) and N was determined with a LECO FP-428 N Analyzer (LECO Corporation,
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Ileal amino acid digestibility
Table 2. Formulation (g/kg) of the assay diets
Table 3. Chemical composition (g/kg, as-fed basis) of the assay diets
diets1
SBM Exp.: 1 and 2 Soybean meal 378 Canola meal – Meat-and-bone meal – Wheat – Alfalfa meal – Sugar beet pulp – Wheat bran – Corn starch 454 Dextrose 100 Canola oil 30 Iodized salt 5 Calcium carbonate 8 Dicalcium phosphate 12 Vitamin and mineral premix2 10 Cr2O3 3
Assay CM MBM Wheat 1 1 1 – 460 – – – 317 – – – 933 – – – – – – – – 384 535 – 100 100 – 30 30 30 5 5 5 8 – 12 – – 7 10 10 10 3 3 3
AM 2 189 – – – 443 – – 207 100 30 5 – 13 10 3
SB 2 236 – – – – 602 – – 100 30 5 – 14 10 3
WB 2 236 – – – – – 414 189 100 30 5 13 – 10 3
1SBM = soybean meal; CM = canola meal; MBM = meat-and-bone meal; AM = alfalfa meal; SB = sugar beet pulp; WB = wheat bran. 2The vitamin and mineral premix provided the following per kilogram of diet: 5,000 IU vitamin A, 500 IU vitamin D3, 40 IU vitamin E, 2 mg vitamin K3, 30 µg vitamin B12, 12 mg riboflavin, 40 mg niacin, 25 mg pantothenic acid, 300 mg choline, 1,600 mg folic acid, 150 mg Fe, 100 mg Zn, 12 mg Mn, 20 mg Cu, 0.2 mg I, and 0.3 mg Se.
St. Joseph, MI). Chromic oxide was determined according to Fenton and Fenton (1979). For AA analyses, approximately 0.1 g of sample was weighed into a screwcapped tube and mixed with 3 mL of 6 N HCl. The tubes were purged with N and then hydrolyzed in an oven at 110°C for 24 h. The hydrolyzed samples were mixed with the internal standard, dl-amino-n-butyric acid, and centrifuged at 2,100 × g for 15 min at room temperature. The supernatant of the samples was analyzed according to the method of Jones and Gilligan (1983) using a Varian high performance liquid chromatography system (model 5000; Varian Associates, Sunnyvale, CA). A reverse-phase column was used following the procedures previously described by Dugan et al. (1989). The AA in the samples was derivatized with an o-phthaldialdehyde reagent solution and detected spectrofluorometrically. Methionine and Cys were determined as methionine sulfone and cysteic acid, respectively, after oxidation with 98% performic acid according to the AOAC International (2000). The oxidized samples were dried according to the procedure described by Dugan et al. (1992) and then hydrolyzed in the same manner as the samples that were not oxidized. Analyses of feed ingredients and diets were performed in triplicate and analyses of digesta in duplicate. The apparent ileal digestibility (AID) of AA in the assay diets was calculated using Cr2O3 as an indigestible marker as described by (Eklund et al., 2012).
Downloaded from https://academic.oup.com/jas/article-abstract/92/3/1037/4702211 by Universiteitsbibliotheek Utrecht user on 25 April 2018
Exp.: DM CP Arg His Ile Leu Lys Met Cys Phe Thr Val
SBM 1 and 2 899 177 15.9 6.1 9.7 17.4 12.5 2.4 2.6 9.8 9.3 10.2
Assay diets1 CM MBM Wheat AM 1 1 1 2 913 917 891 924 156 155 136 169 8.9 10.1 5.9 8.1 4.5 3.0 3.2 3.7 6.2 4.5 4.7 6.5 10.6 9.6 8.7 10.7 10.3 9.8 3.7 9.3 3.2 2.2 2.3 2.1 3.8 1.4 3.2 2.3 5.4 4.6 5.6 6.2 7.2 5.4 4.3 6.0 7.7 6.5 5.5 7.2
SB 2 924 172 9.0 4.3 6.8 10.9 9.8 2.1 2.0 6.2 6.2 7.7
WB 2 910 161 9.8 4.3 6.4 10.6 8.7 2.0 2.7 6.2 5.6 7.1
1SBM = soybean meal; CM = canola meal; MBM = meat-and-bone meal; AM = alfalfa meal; SB = sugar beet pulp; WB = wheat bran.
The SID of AA in the assay diets was calculated by correcting AID of AA for basal ileal endogenous AA loss (IAAend), expressed as grams per kilogram DMI. The IAAend was obtained from a literature review by Jansman et al. (2002). The SID of AA in the assay diets were calculated according to the following equation: SIDD = AIDD + (IAAend/AD) × 100%, in which SIDD = SID of AA in the assay diets (%), AIDD = AID of AA in the assay diets (%), IAAend = basal ileal endogenous loss of AA (g/kg DMI), and AD = AA content in the assay diets (g/kg DMI). The SID of AA originating from AM, SB, or WB in Exp. 2 was calculated according to the following equation: SIDA = (SIDD – SIDB × CB)/CA, in which CB is the contribution level of AA from SBM to the assay diet (%) and CA is the contribution level of AA from the assay feed ingredient to the assay diet (%). Data were analyzed by ANOVA using the PROC MIXED of SAS (SAS Inst. Inc., Cary, NC). Fixed effects included animals and assay diets. Periods and animals within experiments were considered as random effects assuming a compound symmetry variance-covariance structure. A probability level of P < 0.05 was defined as significant difference. Significant differences between treatments were represented by different superscript letters using the algorithm for letter-based representation of all pairwise comparisons according to Piepho (2004).
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Table 4. Standardized ileal digestibility of AA (%) in the assay feed ingredients1
Exp.: n: Arg His Ile Leu Lys Met Cys Phe Thr Val
SBM
CM
MBM
Wheat
AM
SB
WB
P-value
1 and 2 16 (8 + 8) 96 ± 1.5d 95 ± 1.3c 93 ± 1.4d 93 ± 1.3e 92 ± 1.5f 92 ± 1.0e 85 ± 3.2d 92 ± 1.5e 91 ± 2.1f 94 ± 1.4e
1 8 84 ± 2.2c 82 ± 2.0b 72 ± 2.1b 76 ± 2.0c 77 ± 2.3d 79 ± 1.5c 67 ± 4.9c 75 ± 2.2c 69 ± 3.2d 73 ± 2.1c
1 7 88 ± 2.0c 85 ± 1.9b 84 ± 1.9c 84 ± 1.9d 86 ± 2.1e 85 ± 1.4d 60 ± 4.6c 84 ± 2.1d 79 ± 3.0e 85 ± 2.0d
1 8 84 ± 2.0c 86 ± 1.9b 85 ± 1.9c 85 ± 1.9d 68 ± 2.1c 84 ± 1.4d 86 ± 5.4d 93 ± 2.1e 77 ± 3.0ed 84 ± 2.0d
2 6 59 ± 2.4a 51 ± 2.2a 54 ± 2.3a 53 ± 2.2a 31 ± 2.4a 71 ± 1.7b 29 ± 5.3b 48 ± 2.4a 41 ± 3.5b 52 ± 2.3b
2 6 54 ± 2.4a 52 ± 2.2a 53 ± 2.3a 51 ± 2.2a 56 ± 2.4b 61 ± 1.7a –21 ± 5.3a 46 ± 2.4a 30 ± 3.5a 43 ± 2.3a
2 6 76 ± 2.4b 80 ± 2.2b 68 ± 2.3b 68 ± 2.2b 62 ± 2.4cb 69 ± 1.7b 63 ± 5.4c 64 ± 2.4b 55 ± 3.5c 67 ± 2.3c
