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Standardized ileal amino acid digestibility in dry-extruded expelled soybean meal, extruded canola seed-pea, feather meal, and poultry by-product meal for broiler chickens
Standardized ileal amino acid digestibility in dry-extruded expelled soybean meal, extruded canola seed-pea, feather meal, and poultry by-product meal for broiler chickens A. Bandegan,* E. Kiarie,* R. L. Payne,† G. H. Crow,* W. Guenter,* and C. M. Nyachoti*1 *Department of Animal Science, University of Manitoba, Winnipeg, Manitoba, Canada, R3T 2N2; and †Evonik Degussa Corporation, Kennesaw, GA 30144-3694 ileal digestibility (SID) values were calculated using ileal endogenous AA losses previously determined in our laboratory. The apparent ileal digestibility of AA ranged from 78 to 91%, 68 to 83%, 51 to 81%, and 39 to 74% for DESBM, ECSP, PBPM, and FM, respectively. The respective ranges for SID values were 83 to 96%, 72 to 85%, 58 to 86%, and 42 to 78%. Among the indispensable AA, the lowest SID was observed for Thr in all test ingredients, whereas the highest SID was observed for Phe except in ECSP in which Arg had the highest SID. The SID of Lys (CV) were 91% (2.8%), 79% (2.0%), 78% (7.4%), and 60% (10%) for DESBM, ECSP, PBPM, and FM, respectively, whereas the SID of TSAA (CV) were 88% (4.5%), 77% (2.4%), 74% (9.0%), and 55% (18%), respectively. These SID AA data will help nutritionists to formulate broiler diets that more closely match the birds’ requirements and minimize nutrient excess.
Key words: standardized ileal digestibility, apparent ileal digestibility, amino acid, broiler, processed feedstuff 2010 Poultry Science 89:2626–2633 doi:10.3382/ps.2010-00757
INTRODUCTION There is a wide range of feedstuffs used to supply protein and amino acids (AA) in poultry diets. The contents of AA in these feedstuffs that is available to the bird varies widely, especially in those ingredients that have undergone further processing or are generated as by-products of other industries (NRC, 1994). To optimize the utilization of such ingredients in practical poultry feed formulation, it is critical to characterize their available AA. However, because of the difficulties associated with the routine determination of AA availability, ileal digestibility measurements have been suggested as reasonable estimates of availability (Lemme et al., 2004). Although AA digestibility values for most poultry feedstuffs have been reported, the majority of ©2010 Poultry Science Association Inc. Received March 8, 2010. Accepted June 7, 2010. 1 Corresponding author: [email protected]
these estimates have been determined at the excreta level using the adult rooster assay (Parsons, 1991; NRC, 1994; Rhone-Poulenc, 1995; Heartland Lysine, 1996). Although digestibility estimates from adult rooster assays are widely applied to all classes of poultry diet formulations, criticisms have arisen from the fact that crop intubation is not a normal feeding pattern, and estimations carried out in adult, physiologically mature birds might not reflect the digestive capabilities of younger chickens (Ravindran et al., 1999; Lemme et al., 2004). An alternative to the precision-fed rooster assay is to determine digestibility estimates at the ileal level using the broiler chicken (Lemme et al., 2004). Currently, because this is a newer assay, there is a lack of data on the ileal AA digestibility for many feedstuffs. Where data do exist, most have been reported based on apparent ileal digestibility (AID) as opposed to standardized ileal digestibility (SID) estimates. It has been suggested that SID estimates should be used in formulating
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ABSTRACT Ileal digestibility of amino acids (AA) in dry-extruded expelled soybean meal (DESBM), coextruded canola seed-pea blend (ECSP, 50:50 wt/wt basis), poultry by-product meal (PBPM), and feather meal (FM) were determined in broiler chicks. For each ingredient, 5 samples each collected on different occasions were evaluated. Birds (n = 180 for each sample) were fed a commercial starter diet from d 1 to 15 of age followed by the test diets from d 15 to 21. Dry-extruded expelled soybean meal, ECSP, PBPM, and FM were included in the test diets at 95.3, 95.3, 38.4, and 28.4%, respectively, as the sole source of AA and balanced for minerals and vitamins. Chromic oxide (0.3%) was included in all diets as a digestibility marker. Each diet (5 per ingredient) was randomly assigned to 6 replicate cages, each with 6 birds. On d 21, birds were killed to collect ileal digesta for determining the apparent ileal AA digestibility on cage basis. The standardized
AMINO ACID DIGESTIBILITY IN PROCESSED FEEDS FOR BROILERS
MATERIALS AND METHODS Diets Five samples each of DESBM (Jordan Mills Inc., Delmar Commodities Ltd., Winkler, Manitoba, Canada), ECSP (EXP Feeds Inc., Shoal Lake, Manitoba, Canada), PBPM, and FM (Rothsay’s rendering plant, Win-
nipeg, Manitoba, Canada) were obtained from 5 different processing days. Thus, within feedstuff, 5 test diets were made each for each sampling-processing day. Each test diet contained a DESBM, ECSP, FM, or PBPM sample at 95.3, 95.3, 38.4, and 28.4%, respectively, as the sole source of protein and AA. Dextrose and canola oil were added in the PBPM (51.2 and 1.4%, respectively) and FM (59.5 and 3.1%, respectively) for palatability. Additionally, Solkafloc (MP Biochemicals, Solon, OH) was included at 3% in PBPM and FM test diets as a source of fiber. All test diets were balanced for mineral and vitamin levels to meet NRC (1994) requirement recommendations and contained chromic oxide (0.3%) as a digestibility marker.
Birds and Experimental Conduct The experimental protocol was reviewed and approved by the Animal Care Protocol Management and Review Committee of the University of Manitoba. Birds were cared for according to the guidelines of the Canadian Council on Animal Care (1993). One hundred eighty broiler chickens were used to assay each sample in 3 separate experiments, one for each feedstuff except for PBPM and FM samples, which were assayed together. The chicks were obtained from a local hatchery (Carlton Hatchery, Grunthal, Manitoba, Canada) and housed in Petersime battery brooders (Petersime Incubator Co., Gettysburg, OH) in a room with continuous fluorescent lighting. Room temperature was maintained at 32, 28, and 24°C during wk 1, 2, and 3, respectively. From d 1 to 14, birds were fed a commercial chick starter diet (FeedRite, Ridley Inc., Winnipeg, Manitoba, Canada) in crumble form (2,713 kcal/kg of AME, 20.8% CP, 0.96% total Lys, 0.4% total Met, 0.8% TSAA, 0.53% available P, 0.97% Ca, and phytase at 500 phytase units/kg). On d 14, birds were fasted for 3 h, weighed, and distributed 6 birds/ cage based on BW. Within a feedstuff, 6 replicate cages were randomly assigned to each of the 5 test diets and fed from d 15 to 21. Birds had ad libitum access to feed and water throughout the study period. On d 21, birds were killed by cervical dislocation and the digesta from the ileum (from Meckel’s diverticulum to a point 4 cm proximal to the ileocecal junction) were collected by gently squeezing the contents of the ileum into sample bags (Bandegan et al., 2009). Digesta from birds within a cage were pooled into 1 bag and frozen immediately after collection and subsequently freeze-dried. The dried ileal digesta were stored in airtight bags at −4°C until required for chemical analysis.
Chemical Analysis Raw feed ingredients, test diets, and digesta samples were finely ground using a coffee grinder (CBG5 Smart Grind, Applica Consumer Products Inc., Shelton, CT). Dry matter was determined according to AOAC (1990, method 925.09) and CP (N × 6.25) was determined by
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poultry diets because these are likely more additive in a mixture of feedstuffs compared with AID estimates (Angkanaporn et al., 1996). Furthermore, formulating broiler diets based on SID AA estimates results in rations that more closely match the birds’ requirements and reduce excess nutrients (Adedokun et al., 2007). Corn and soybean meal prices have been at record levels and when the prices of these basic ingredients are high, the use of alternative ingredients such as animal by-products and ingredients resulting from novel processing techniques such as dry-extruded soybean meal (DESBM) and extruded canola seed-pea blend (ECSP; 50:50 wt/wt) in broiler feed formulations becomes economically attractive. However, good nutritional information, especially regarding the available AA contents, is lacking. There has been a long history of use of poultry byproduct meal (PBPM) and feather meal (FM) in the poultry industry worldwide. However, the wide variation in digestible AA in these by-products, which primarily depends on the processing system, is often of great concern (NRC, 1994; Wang and Parsons, 1997). As a consequence, there have been some concerted efforts by renderers to improve the quality of their ingredients and adapt to standard regulations and manufacturing practices accordingly (Prokop, 1996; Keegan et al., 2004). There are only a few studies on the SID of AA in PBPM and FM fed to broilers (Garcia et al., 2007). Extrusion processing followed by expelling is a relatively recent technology developed for soybean meal processing. This technology has been adopted as an alternative means of producing soybean meal and other oilseed meal and oils for human consumption or the livestock industry, or both (Webster et al., 2003). The extruder-expeller process results in a product (DESBM) that has a higher fat content compared with solventextracted soybean meal (Webster et al., 2003; Opapeju et al., 2006). A co-extruded blend of canola seed and pea (50:50 wt/wt) has been evaluated as a potential high-energy and protein ingredient for poultry and swine in Western Canada (Golian et al., 2007; Kiarie and Nyachoti, 2007). Previous studies in our laboratory reported AA digestibility in DESBM and ECSP fed to roosters (Opapeju et al., 2006; Golian et al., 2007). However, reports regarding SID of AA in DESBM and ECSP fed to broilers are very limited. Thus, this study was conducted to determine the SID estimates of protein and AA and their associated CV in DESBM, ECSP, PBPM, and FM for broilers.
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Bandegan et al.
434; Trp, 71; Val, 270; Ala, 217; Asp, 430; Cys, 143; Glu, 492; Gly, 245; Pro, 289; and Ser, 343.
Statistical Analysis The data for digestibility estimates of the samples were analyzed using the GLM procedure of SAS Institute (1990) as a completely randomized design. The nested procedure was applied to further analyze the random feed samples and bird-cage subsampling effects on the total variation observed. For a better demonstration of variability, the components of total CV associated with the AID and SID estimates for each AA across different feed samples are included as variance due to the samples
(s ) 2 s
and cages within samples
(s ). 2 e
RESULTS AND DISCUSSION
Digestibility Calculation The AID coefficient of AA was calculated as described by Bandegan et al. (2009). The SID coefficients of AA were calculated as follows: SID% = AID + [(basal IAAend/AAdiet) × 100], where IAAend = basal ileal endogenous AA loss. Basal endogenous loss estimates (mg/kg of DM intake) previously determined by Golian et al. (2008) using a N-free diet were used to calculate the SID values, and those estimates were as follows: CP, 4,365; Arg, 203; His, 91; Ile, 200; Leu, 298; Lys, 173; Met, 65; Phe, 420; Thr,
Crude protein and AA composition of DESBM, ECSP, PBPM, and FM are presented in Tables 1 and 2. The CP and AA composition of DESBM and ECSP compare well with previously published values (Woodworth et al., 2001; Opapeju et al., 2006; Golian et al., 2007). Among the indispensable AA content, Met and His ranked lowest, whereas Leu, Arg, and Lys ranked highest in both the DESBM and ECSP samples. Previous reports indicated that extrusion decreased the content of some AA including His, Met, and Cys in peas, soybean meal, and field beans (Jeunink and Cheftel, 1979; Cheftel, 1986; Prudencio-Ferreira and Areas, 1993; Alonso et al., 2000). A comparison between raw
Table 1. Crude protein and amino acid (AA) composition (%) of DESBM and ECSP samples (DM basis)1 DESBM (n = 5) Item DM CP Indispensable AA Arg His Ile Leu Lys Met TSAA Phe Thr Val Dispensable AA Ala Asp Cys Glu Gly Pro Ser
ECSP (n = 5)
Range
Mean
CV%2
92.3 to 93.9 44.6 to 46.7
93.3 45.8 3.24 1.16 2.04 3.43 2.81 0.67 1.38 2.26 1.82 2.15 1.96 5.18 0.71 8.04 1.93 2.14 2.32
0.7 1.9 1.4 2.0 1.3 1.6 1.9 1.3 1.6 2.0 1.8 1.2 1.5 1.8 2.0 1.9 1.6 1.7 1.9
3.19 1.14 2.01 3.37 2.75 0.66 1.37 2.21 1.80 2.12
to to to to to to to to to to
3.31 1.20 2.07 3.49 2.88 0.68 1.42 2.32 1.85 2.18
1.92 5.08 0.70 7.90 1.90 2.09 2.27
to to to to to to to
1.99 5.28 0.74 8.17 1.96 2.19 2.36
Range
Mean
CV%
92.9 to 94.6 23.7 to 24.2 1.52 to 1.61 0.55 to 0.59 0.94 to 0.98 1.64 to 1.70 1.28 to 1.37 0.34 to 0.39 0.76 to 0.85 1.03 to 1.10 0.94 to 0.96 1.12 to 1.20 1.00 to 1.04 2.02 to 2.21 0.42 to 0.47 3.83 to 4.01 1.03 to 1.08 1.08 to 1.17 1.05 to 1.13
93.5 24.0 1.58 0.57 0.96 1.68 1.34 0.37 0.81 1.08 0.95 1.16 1.02 2.14 0.44 3.90 1.06 1.11 1.10
0.7 0.7 2.3 2.5 2.2 1.4 2.8 4.8 4.8 2.4 1.1 2.4 1.6 3.6 5.0 1.8 1.6 3.1 2.9
1Samples of each ingredient collected at 5 different processing days to constitute 5 independent assay samples. DESBM = dry-extruded soybean meal; ECSP = extruded canola seed-pea blend 50:50 wt/wt. 2Coefficient of variation among different samples.
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the combustion (method 990.03, AOAC, 1990) using a combustion analyzer (model CNS-2000, Leco Corp., St. Joseph, MI) and EDTA as a calibration standard. Amino acid concentrations were determined by Evonik Industries (Hanau-Wolfgang, Germany) using ion-exchange chromatography with postcolumn derivatization with ninhydrin (Llames and Fontaine, 1994). Sulfur AA (Met and Cys) were first oxidized with performic acid, which was subsequently neutralized with sodium metabisulfite (Commission Directive, 1998). Amino acid concentrations were quantified with the internal standard method by measuring the absorption of reaction products with ninhydrin at 570 nm. Chromium was analyzed, after the samples were ashed at 600°C for 12 h in a muffle furnace, using inductively coupled plasma mass spectrometry (ICP-AES Vista, Varian, Palo Alto, CA) according to the method of AOAC (2005, method 985.01).
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AMINO ACID DIGESTIBILITY IN PROCESSED FEEDS FOR BROILERS Table 2. Crude protein and amino acid (AA) composition (%) of PBPM and FM samples (DM basis)1 PBPM (n = 5) Mean
CV%2
96.5 to 97.0 61.6 to 63.5 4.04 to 4.16 1.25 to 1.34 2.03 to 2.13 4.02 to 4.18 3.53 to 3.68 1.05 to 1.09 1.54 to 1.62 2.24 to 2.32 2.16 to 2.24 2.70 to 2.86 4.16 to 4.28 4.76 to 4.96 0.48 to 0.53 7.60 to 7.90 6.53 to 6.63 3.94 to 4.08 2.32 to 2.44
96.8 62.6 4.11 1.29 2.08 4.07 3.59 1.07 1.58 2.28 2.20 2.78 4.21 4.85 0.51 7.74 6.57 3.99 2.37
0.19 1.1 1.2 3.1 1.8 2.0 1.8 1.5 2.0 1.6 1.7 2.2 1.2 1.6 3.5 1.5 0.6 1.4 2.2
Range
91.8 to 95.6 88.7 to 98.3 6.04 to 6.69 0.69 to 0.76 4.09 to 4.67 6.96 to 7.80 1.89 to 2.14 0.59 to 0.64 4.47 to 5.10 4.14 to 4.86 3.99 to 4.44 6.22 to 7.37 3.89 to 4.35 5.98 to 6.61 3.84 to 4.51 9.40 to 10.13 6.82 to 7.69 8.11 to 9.13 9.25 to 10.93
Mean
CV%
93.8 95.0 6.37 0.74 4.40 7.41 1.98 0.61 4.72 4.53 4.24 6.82 4.14 6.30 4.11 9.79 7.26 8.60 10.24
1.65 4.1 4.5 4.0 6.2 5.4 5.2 3.5 6.7 7.4 4.8 7.6 4.8 4.7 8.1 3.7 5.4 6.5 7.1
1Samples of each ingredient collected at 5 different processing days to constitute 5 independent assay samples. PBPM = poultry by-product meal; FM = feather meal. 2Coefficient of variation among different samples.
Table 3. Apparent ileal digestibility coefficients and their associated CV determined in chicks fed DESBM and ECSP samples1 DESBM
ECSP Variance components3
Item
Range
CP Indispensable AA4 Arg His Ile Leu Lys Met TSAA Phe Thr Val Dispensable AA Ala Asp Cys Glu Gly Pro Ser 1Five
Mean
CV%2
Between
Within
82.1 to 89.2
86.0
4.2
58.7
41.3
88.8 85.0 84.0 84.2 86.7 88.0 82.0 86.2 78.4 82.1
to to to to to to to to to to
93.6 92.0 90.7 90.6 91.6 92.6 86.8 91.9 85.5 89.0
91.4 89.1 87.3 87.6 89.4 90.5 84.3 89.1 82.6 85.5
2.7 3.2 3.9 3.7 2.9 2.9 4.6 3.3 4.8 4.1
49.1 44.3 52.1 57.2 44.2 45.1 39.1 55.2 50.5 53.2
50.9 55.7 47.9 42.8 55.8 54.9 60.9 44.8 49.5 46.8
83.2 81.9 72.1 87.2 79.2 83.1 81.3
to to to to to to to
89.1 89.0 81.1 92.3 86.0 89.0 87.7
86.5 85.8 78.0 90.0 83.1 86.4 85.3
3.6 4.1 6.9 3.1 4.3 3.7 4.0
53.0 46.5 36.1 41.2 46.3 46.2 53.9
47.0 53.5 63.9 58.8 53.7 53.8 46.1
Variance components
Range
Mean
CV%
Between
Within
70.3 to 73.3
71.5
2.3
40.8
59.2
82.2 72.6 71.7 73.9 76.1 79.4 72.9 73.3 66.6 70.3
to to to to to to to to to to
84.4 76.6 74.1 76.3 78.8 83.5 76.2 76.1 70.3 73.1
83.3 75.2 72.8 74.9 77.4 81.6 74.5 74.2 67.8 71.6
1.5 3.8 2.3 2.0 2.1 2.6 2.5 2.7 3.1 2.4
39.6 21.5 23.1 30.4 40.2 38.0 36.6 21.5 39.3 40.7
60.4 78.5 76.9 69.6 59.8 62.0 63.4 78.5 60.7 59.3
74.0 72.1 67.4 79.8 70.0 71.1 68.5
to to to to to to to
76.2 75.5 69.4 82.0 72.8 73.4 71.8
74.8 73.4 68.4 80.8 71.2 71.9 69.5
2.0 2.5 2.7 1.6 2.4 2.0 2.9
27.2 44.6 12.3 34.2 32.1 26.3 30.4
72.8 55.4 87.7 65.8 67.9 73.7 69.6
( )
samples of each feed ingredient were assayed in 6 replicate cages with 6 birds in each and variance components for samples ss2 and cages
( )
within samples se2 were determined. DESBM = dry-extruded soybean meal; ECSP = extruded canola seed-pea blend 50:50 wt/wt. 2Total
CV: CV% =
3Percentage 4AA
ss2 + se2 y
´ 100%, where y = mean.
(
)
(
)
contribution to the total variation calculated as ss2 / ss2 + se2 and se2 / ss2 + se2 for samples and cages within samples, respectively.
= amino acid.
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Range
Item DM CP Indispensable AA Arg His Ile Leu Lys Met TSAA Phe Thr Val Dispensable AA Ala Asp Cys Glu Gly Pro Ser
FM (n = 5)
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Bandegan et al.
Table 4. Standardized ileal digestibility coefficients and their associated CV determined in chicks fed DESBM and ECSP samples1 DESBM
ECSP Variance components3
Mean
CV%2
Between
Within
Range
Mean
CV%
Between
Within
84.4 to 91.4
88.2
4.0
42.3
57.7
72.2 to 75.2
73.4
2.3
40.4
59.6
90.3 86.7 86.4 86.3 88.1 90.1 83.4 93.2 84.0 85.1
to to to to to to to to to to
95.1 92.0 92.9 92.6 93.1 94.7 90.2 98.9 91.1 91.9
92.9 89.6 89.5 89.6 90.8 92.5 87.5 95.9 88.0 88.4
2.7 3.2 3.7 3.6 2.8 2.9 4.5 3.1 4.4 4.0
51.1 55.7 48.2 43.0 55.8 54.6 60.9 45.1 49.8 47.0
48.9 44.3 51.8 57.0 44.2 45.4 39.1 54.9 50.2 53.0
83.7 74.2 74.0 75.8 77.5 81.3 75.6 80.2 71.5 72.8
to to to to to to to to to to
85.7 78.3 76.4 78.2 80.2 85.2 78.8 82.9 75.2 75.7
84.7 76.8 75.0 76.8 78.8 83.4 77.1 80.9 72.7 74.1
1.5 3.7 2.2 1.9 2.0 2.4 2.4 2.4 2.9 2.3
37.0 20.9 22.1 30.2 38.7 35.5 35.1 17.7 39.7 39.5
63.0 79.1 77.9 69.8 61.3 64.5 64.9 82.3 60.3 60.5
85.7 83.9 76.7 88.6 82.2 86.2 84.8
to to to to to to to
91.7 90.9 85.6 93.8 89.0 92.1 91.2
89.0 87.7 82.5 91.4 86.0 89.4 88.6
3.5 4.0 6.5 3.1 4.2 3.6 3.8
46.9 53.7 64.5 58.8 53.7 54.3 46.8
53.1 46.3 35.5 41.2 46.3 45.7 53.2
76.3 74.3 70.8 81.2 72.5 73.6 71.9
to to to to to to to
78.5 77.7 72.9 83.4 75.3 76.0 75.2
77.1 75.5 71.8 82.1 73.6 74.4 72.9
1.9 2.4 2.6 1.5 2.4 2.0 2.8
27.4 43.4 13.3 33.8 32.1 27.0 30.4
72.6 56.6 86.7 66.2 67.9 73.0 69.6
1Five
( )
samples of each feed ingredient (n = 5) were assayed in 6 replicate cages with 6 birds in each and variance components for samples ss2 and
cages within samples 2Total
CV: CV% =
3Percentage 4AA
( ) were determined. DESBM = dry-extruded soybean meal; ECSP = extruded canola seed-pea blend 50:50 wt/wt. se2
ss2 + se2 y
´ 100%, where y = mean.
(
)
(
)
contribution to the total variation calculated as ss2 / ss2 + se2 and se2 / ss2 + se2 for samples and cages within samples, respectively.
= amino acid.
and processed products for the effect of extrusion on AA content was not made in this study; however, in a comparison between the raw and extruded canola seed and pea blend, Golian et al. (2007) concluded that extrusion decreased Glu and Gly contents. The CV for AA ranged from 1.2% (Val) to 2.0% (His, Phe, and Cys) and 1.1% (Thr) to 5.0% (Met and Cys) for DESBM and ECSP, respectively. The CP and AA composition of PBPM and FM samples compared well with previously published values (Daghir, 1975; Johnston and Coon, 1979; Baker et al., 1981; Papadopoulos et al., 1986; Wang and Parsons, 1998; Ravindran et al., 2005). The AA profile of PBPM and FM showed a somewhat similar trend, with Met and His ranking the lowest. On the other hand, Leu and Arg in PBPM and Leu and Val in FM ranked the highest. Generally, a wider CV range (3.5 to 8.1%) was observed for AA profile in FM than in PBPM (0.6 to 3.5%). Cysteine was the most variable AA in both PBPM (3.5%) and FM (8.1%). It has been shown that processing conditions have a substantial effect on reducing Cys, Met, Lys, and His contents in FM (Moran et al., 1966; Eggum, 1970; Papadopoulos et al., 1986). The AID of AA in DESBM and ECSP ranged from 78% (Cys) to 91% (Arg) and 68% (Cys) to 83% (Arg), respectively (Table 3), whereas the corresponding SID values ranged from 83% (Cys) to 96% (Phe) and 72%
(Cys) to 85% (Arg), respectively (Table 4). Among the indispensible AA, Thr had the least AID and SID estimates in both DESBM and ECSP. Threonine is a major AA in endogenous secretions, which may partly explain the reason for its lower digestibility (Siriwan et al., 1993; Ravindran and Hendriks, 2004a). The highest CV for SID estimates was observed for Cys (6.9%) and His (3.8%) in DESBM and ECSP, respectively, which on further partitioning revealed that 36 and 22% of the CV was due to the variation between the samples, respectively. This means that the highest variation observed for SID estimates in DESBM and ECSP was more affected by the assay conditions than the feed samples. Estimates for the SID AA in DESBM and ECSP in broilers have not been reported in the literature. Nevertheless, the SID values determined in this study were lower than the true AA digestibility values determined in cecectomized roosters with different batches of DESBM (Opapeju et al., 2006) and for ECSP (Golian et al., 2007). Similarly, Garcia et al. (2007) reported lower digestible AA estimates for soybean meal in broilers than in roosters. The AID results show a shorter AA digestibility range for PBPM (51 to 81%) compared with FM (39 to 74%) (Table 5). Cysteine (51%) and Asp (39%) were the least digestible AA in PBPM and FM, respectively; however, Thr (70%) in PBPM and Lys and Thr (56%)
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Range
Item CP Indispensable AA4 Arg His Ile Leu Lys Met TSAA Phe Thr Val Dispensable AA Ala Asp Cys Glu Gly Pro Ser
Variance components
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AMINO ACID DIGESTIBILITY IN PROCESSED FEEDS FOR BROILERS
Table 5. Apparent ileal amino acid (AA) digestibility coefficients and their associated CV determined in chicks fed PBPM and FM samples1 PBPM
FM Variance components3
Item
Range
1Five
CV%2
Between
Within
Range
Mean
CV%
Between
Within
74.2 66.1 65.9 69.2 67.8 73.0 60.6 69.8 59.4 66.6
to to to to to to to to to to
84.9 80.9 80.5 82.7 81.9 84.5 76.7 83.3 76.2 80.8
81.2 75.5 75.2 77.8 76.7 80.3 70.9 78.2 70.2 75.7
5.7 8.0 8.0 7.1 7.5 6.0 9.4 7.1 10.0 7.8
75.2 83.3 80.8 81.5 82.9 79.1 80.9 79.7 81.3 80.3
24.8 16.7 19.2 18.5 17.1 20.9 19.1 20.3 18.7 19.7
75.2 52.3 70.9 65.8 51.5 63.3 43.4 69.4 48.8 66.5
to to to to to to to to to to
66.6 63.2 78.8 75.7 60.5 71.0 59.7 78.6 63.0 76.6
70.5 57.7 74.1 70.0 56.4 67.9 53.1 73.3 56.4 71.3
8.6 10.7 7.6 9.4 10.4 7.0 18.6 8.3 13.9 9.6
3.7 18.2 3.0 6.4 12.6 16.2 20.4 5.9 24.1 6.6
96.3 81.8 97.0 93.6 87.4 83.8 79.6 94.1 75.9 93.4
71.1 44.7 34.0 66.6 66.4 61.4 57.3
to to to to to to to
83.2 67.6 59.8 80.8 80.6 76.8 74.9
78.9 59.0 50.6 75.8 75.7 71.3 68.4
6.4 15.7 21.5 7.8 8.4 9.1 10.6
78.8 82.8 77.2 79.4 67.9 78.5 81.1
21.2 17.2 22.8 20.6 32.1 21.5 18.9
63.9 26.6 38.9 67.8 62.7 52.3 58.5
to to to to to to to
74.3 48.3 58.0 55.2 74.4 66.4 71.5
68.1 39.4 50.4 62.3 68.7 59.9 65.2
10.3 27.7 22.5 12.7 11.1 13.2 11.3
5.0 40.8 23.9 14.0 9.0 21.7 19.2
95.0 59.2 76.1 86.0 91.0 78.3 80.8
( )
samples of each feed ingredient were assayed in 6 replicate cages with 6 birds in each and variance components for samples ss2 and cages
within samples 2Total
( ) were determined. PBPM = poultry by-product meal; FM = feather meal. se2
CV: CV% =
3Percentage
ss2 + se2 y
´ 100%, where y = mean.
(
)
(
)
contribution to the total variation calculated as ss2 / ss2 + se2 and se2 / ss2 + se2 for samples and cages within samples, respectively.
in FM were the least digestible among the indispensible AA. In contrast, Arg (81%) in PBPM and Ile (74%) in FM were the most digestible indispensable AA. Other than change in ranking of AA digestibility, the SID values (Table 6) followed a similar trend for all AA as those of AID. Specifically, SID of Cys (57%) in PBPM and Asp (42%) in FM were found to be the least digestible, whereas Phe was the most digestible in both. Comparing the SID values of both FM and PBPM shows that Lys was among the least digestible AA in FM (60%), whereas it was better digested in PBPM (78%). Results published for the average true AA digestibility estimates for FM and PBPM in NRC (1994) are somewhat higher than those found in the present study. This could be partly explained by the fact that the sample source, methodology, and age of the birds used in experiments can affect digestibility results from different assays (Ten Doeschate et al., 1993; Ravindran and Hendriks, 2004b; Garcia et al., 2007). As mentioned earlier, digestibility estimates of processed products are very variable and this might be due to the feed samples used or assay condition, yet the pooled variation reported in the literature lacks the transparency required to explain them separately. Because total variation observed in estimating AID and SID values is affected by both the feed samples (between) and assay condition (within), it is of benefit to separate the total variance into these components to
demonstrate their contribution separately. Overall, the range of CV values associated with the AID estimates of AA in PBPM was shorter (5.7 to 22%) and was mostly due to the feed sample, whereas those of FM varied more (7.0 to 28%) and were mainly due to the assay condition (cage-to-cage differences). The CV associated with AID estimates of Cys and Asp was the most variable of all AA in both PBPM and FM. Low Met, Lys, and His contents together with their lower digestibility in FM has been reported before (Moran et al., 1966; Morris and Balloun, 1973; Baker et al., 1981). It has been shown that AA imbalance in feed can reduce appetite (Peng and Harper, 1970). If the CV associated with AID values for each FM sample is because of depressed appetite and varied feed intake of the birds, then the total CV of each AA determined in FM is expected to be affected by a within-sample component. Therefore, as it was expected, a wider variation of the total CV was due to cage-to-cage difference (within) than the samples themselves (between). On the contrary, PBPM is a more digestible feed than FM and it was shown that mixing PBPM with FM resulted in superior bird performance than using FM alone (Bhargava and O’Neil, 1975; Daghir, 1975). Thus, the total variation observed for each AA estimate in PBPM was more affected by the samples (between) than the assay condition (within).
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Indispensable AA Arg His Ile Leu Lys Met TSAA Phe Thr Val Dispensable AA Ala Asp Cys Glu Gly Pro Ser
Mean
Variance components
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Table 6. Standardized ileal amino acid (AA) digestibility coefficients and their associated CV determined in chicks fed PBPM and FM samples1 PBPM
FM Variance components3
Item
Range
1Five
CV%2
Between
Within
Range
Mean
CV%
Between
Within
75.5 67.8 68.5 71.1 69.1 74.4 79.7 77.5 64.6 69.1
to to to to to to to to to to
86.2 82.5 83.0 84.5 83.1 85.9 63.8 90.6 81.2 83.3
82.5 77.1 77.7 79.7 78.0 81.7 74.1 85.8 75.3 78.2
5.6 7.8 7.7 6.9 7.4 5.9 9.0 6.3 9.2 7.5
75.0 83.1 80.6 81.3 82.8 79.1 80.6 78.8 80.9 80.1
25.0 16.9 19.4 18.7 17.2 20.9 19.4 21.2 19.1 19.9
67.7 55.7 72.5 67.2 54.3 66.2 44.9 74.7 52.3 68.0
to to to to to to to to to to
76.3 66.9 80.3 77.0 63.7 74.2 61.2 83.3 66.4 77.9
71.6 61.3 75.7 71.4 59.5 71.0 54.7 78.4 59.9 72.7
8.4 10.2 7.4 9.2 10.0 6.8 18.1 7.7 13.0 9.4
3.2 19.9 2.4 5.8 15.3 18.3 20.4 3.4 23.2 5.9
96.8 80.1 97.6 94.2 84.7 81.7 79.6 96.6 76.8 94.1
72.4 47.0 41.4 68.3 67.3 63.2 61.1
to to to to to to to
84.4 69.8 66.5 82.4 81.5 78.5 78.4
80.2 61.3 57.6 77.4 76.7 73.1 72.1
6.3 15.1 18.5 7.7 8.3 8.8 9.9
78.7 82.7 76.4 79.3 67.8 78.4 80.7
21.3 17.3 23.6 20.7 32.2 21.6 19.3
65.7 29.0 40.1 56.9 63.9 53.5 59.7
to to to to to to to
76.0 50.6 59.3 69.5 75.5 67.4 72.5
69.9 41.7 51.6 64.1 69.8 61.0 66.3
10.1 26.1 21.9 12.3 10.9 12.9 11.1
4.5 40.4 23.8 13.8 8.6 21.1 18.5
95.5 59.6 76.2 86.2 91.4 78.9 81.5
( )
samples of each feed ingredient were assayed in 6 replicate cages with 6 birds in each and variance components for samples ss2 and cages
within samples 2Total
( ) were determined. PBPM = poultry by-product meal; FM = feather meal. se2
CV: CV% =
3Percentage
ss2 + se2 y
´ 100%, where y = mean.
(
)
(
)
contribution to the total variation calculated as ss2 / ss2 + se2 and se2 / ss2 + se2 for samples and cages within samples, respectively.
For effective diet formulation and optimum use of feedstuff to meet the requirements, it is important that the digestibility values be relevant to the age of the bird to which the diet is being fed. Furthermore, in determining these digestibility values, it is also important to account for and report the variation observed for the feed and methodology separately. A large body of AA digestibility data in the literature has been created (Parsons, 1991; NRC, 1994; Rhone-Poulenc, 1995; Heartland Lysine, 1996) using the cecectomized rooster. Potential drawbacks to this data are the application to broiler diets and that they do not provide a clear expression of variation associated with each of the observations within the assay condition. As such, the AA digestibilities determined at the ileal level are more accurate than digestibilities determined at the excreta level of intact noncecectomized birds (Ravindran et al., 1999; Lemme et al., 2004). Furthermore, it is now clear that ileal AA digestibility values are affected by the methodology and age of the birds used (Ten Doeschate et al., 1993; Ravindran and Hendriks, 2004b; Garcia et al., 2007). Moreover, the SID values as opposed to AID values are better estimates of the AA availability in feedstuff and when used in a mixed diet they have been shown to be additive (Angkanaporn et al., 1996; Stein et al., 2005). Among the feed ingredients tested, DESBM was the most digestible with its SID AA values ranging from
83 to 93% for Cys and Phe, respectively. Poultry byproduct meal was more digestible with lesser variability compared with FM. A common point among the tested processed feeds was that they all had the heat-labile AA, including Lys, sulfur amino acids, and Gly ranked among the lowest SID values, whereas Phe was reported to be stable in thermal processing (Papadopoulos et al., 1986) and was rated as the most digestible AA of all, except in ECSP, in which Arg was the most digestible AA. The CV associated with the SID estimates of AA was higher in FM compared with ECSP, DESBM, and PBPM, with ECSP as the least variable of all. In both FM and PBPM, Asp and Cys estimates of SID were the most variable.
ACKNOWLEDGMENTS We thank Harry Muc (University of Manitoba) for his technical assistance. Funding for this study was provided by Evonik Degussa Corporation (Kennesaw, GA) and the Natural Sciences and Engineering Research Council of Canada (NSERC, Ottawa, Ontario, Canada).
REFERENCES Adedokun, S. A., C. M. Parsons, M. S. Lilburn, O. Adeola, and T. J. Applegate. 2007. Standardized ileal amino acid digestibility of meat and bone meal from different sources in broiler chicks
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Indispensable AA Arg His Ile Leu Lys Met TSAA Phe Thr Val Dispensable AA Ala Asp Cys Glu Gly Pro Ser
Mean
CV (%) contribution
AMINO ACID DIGESTIBILITY IN PROCESSED FEEDS FOR BROILERS
implication of disulfide bonding in raw feathers as the reason for poor digestibility. Poult. Sci. 45:1257–1266. Morris, W. C., and S. L. Balloun. 1973. Effect of processing methods on utilization of feather meal by broiler chicks. Poult. Sci. 52:858–866. NRC. 1994. Nutrient Requirements of Poultry. 9th rev. ed. Natl. Acad. Press, Washington, DC. Opapeju, F. O., A. Golian, C. M. Nyachoti, and L. D. Campbell. 2006. Amino acid digestibility in dry extruded-expelled soybean meal fed to pigs and poultry. J. Anim. Sci. 84:1130–1137. Papadopoulos, M., A. El Boushy, A. Roodbeen, and E. Ketelaars. 1986. Effects of processing time and moisture content on amino acid composition and nitrogen characteristics of feather meal. Anim. Feed Sci. Technol. 14:279–290. Parsons, C. M. 1991. Amino acid digestibilities for poultry: Feedstuff evaluation and requirements. Kyowa Hakko Technical Review-1. Kyowa, Chesterfield, MO. Peng, Y., and A. E. Harper. 1970. Amino acid balance and food intake: Effect of different dietary amino acid patterns on the plasma amino acid pattern of rats. J. Nutr. 100:429–437. Prokop, W. H. 1996. Technological and environmental impacts on the rendering industry. Pages 23–52 in The Original Recyclers: The Animal Protein Industry. Fats and Proteins Research Foundation and National Renderers Association, Alexandria, VA. Prudencio-Ferreira, S. H., and J. A. G. Areas. 1993. Protein-protein interactions in the extrusion of soya at various temperatures and moisture contents. J. Food Sci. 58:378–381. Ravindran, V., and W. H. Hendriks. 2004a. Endogenous amino acid flows at the terminal ileum of broilers, layers and adult roosters. Anim. Sci. 79:265–271. Ravindran, V., and W. H. Hendriks. 2004b. Recovery and composition of endogenous protein collected at the terminal ileum as influenced by the age of broiler chickens. Aust. J. Agric. Res. 55:705–709. Ravindran, V., L. I. Hew, G. Ravindran, and W. L. Bryden. 1999. A comparison of ileal digesta and excreta analysis for the determination of amino acid digestibility in food ingredients for poultry. Br. Poult. Sci. 40:266–274. Ravindran, V., L. I. Hew, G. Ravindran, and W. L. Bryden. 2005. Apparent ileal digestibility of amino acids in dietary ingredients for broiler chickens. Anim. Sci. 81:85–97. Rhone-Poulenc. 1995. Digestibility Database for Poultry. RhonePoulenc Anim. Nutr., Antony, France. SAS Institute. 1990. SAS/STAT User’s Guide. Version 6. 4th ed. SAS Inst. Inc., Cary, NC. Siriwan, P., W. L. Bryden, Y. Mollah, and E. F. Annison. 1993. Measurement of endogenous amino acid losses in poultry. Br. Poult. Sci. 34:939–949. Stein, H., C. Pedersen, A. Wirt, and R. Bohlke. 2005. Additivity of values for apparent and standardized ileal digestibility of amino acids in mixed diets fed to growing pigs. J. Anim. Sci. 83:2387– 2395. Ten Doeschate, R. A. H. M., C. W. Scheele, V. V. A. M. Schreurs, and J. D. Van Der Klis. 1993. Digestibility studies in broiler chickens: Influence of genotype, age, sex and method of determination. Br. Poult. Sci. 34:131–146. Wang, X., and C. Parsons. 1998. Order of amino acid limitation in poultry by-product meal. Br. Poult. Sci. 39:113–116. Wang, X., and C. M. Parsons. 1997. Effect of processing systems on protein quality of feather meals and hog hair meals. Poult. Sci. 76:491–496. Webster, M. J., R. D. Goodband, M. D. Tokach, J. L. Nelssen, S. S. Dritz, J. C. Woodworth, M. De La Llata, and N. W. Said. 2003. Evaluating processing temperature and feeding value of extruded-expelled soybean meal on nursery and finishing pig growth performance. J. Anim. Sci. 81:2032–2040. Woodworth, J. C., M. D. Tokach, R. D. Goodband, J. L. Nelssen, P. R. O’Quinn, D. A. Knabe, and N. W. Said. 2001. Apparent ileal digestibility of amino acids and the digestible and metabolizable energy content of dry extruded-expelled soybean meal and its effects on growth performance of pigs. J. Anim. Sci. 79:1280–1287.
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and turkey poults with a nitrogen-free or casein diet. Poult. Sci. 86:2598–2607. Alonso, R., G. Grant, P. Dewey, and F. Marzo. 2000. Nutritional assessment in vitro and in vivo of raw and extruded peas (Pisum sativum L.). J. Agric. Food Chem. 48:2286–2290. Angkanaporn, K., V. Ravindran, and W. L. Bryden. 1996. Additivity of apparent and true ileal amino acid digestibilities in soybean meal, sunflower meal, and meat and bone meal for broilers. Poult. Sci. 75:1098–1103. AOAC. 1990. Official Methods of Analysis. 15th ed. AOAC Int., Arlington, VA. AOAC. 2005. Official Methods of Analysis. 18th ed. AOAC Int., Arlington, VA. Baker, D., R. Blitenthal, K. Boebel, G. Czarnecki, L. Southern, and G. Willis. 1981. Protein-amino acid evaluation of steam-processed feather meal. Poult. Sci. 60:1865–1872. Bandegan, A., W. Guenter, D. Hoehler, G. H. Crow, and C. M. Nyachoti. 2009. Standardized ileal amino acid digestibility in wheat distillers dried grains with solubles for broilers. Poult. Sci. 88:2592–2599. Bhargava, K. K., and J. B. O’Neil. 1975. Composition and utilization of poultry by-product and hydrolyzed feather meal in broiler diets. Poult. Sci. 54:1511–1518. Canadian Council on Animal Care. 1993. Guide to the Care and Use of Experimental Animals. Vol. 1. 2nd ed. Can. Counc. Anim. Care, Ottawa, Ontario, Canada. Cheftel, J. C. 1986. Nutritional effects of extrusion-cooking. Food Chem. 20:263–283. Commission Directive. 1998. Establishing community methods for the determination of amino acids, crude oils and fats, and olanquindox in feeding stuff and amending Directive 71/393/EEC, annex part A. Determination of amino acids. Off. J. Eur. Communities L 257:14–23. Daghir, N. 1975. Studies on poultry by-product meals in broiler and layer rations. World’s Poult. Sci. J. 31:200–211. Eggum, B. O. 1970. Evaluation of protein quality of feather meal under different treatments. Acta Agric. Scand. 20:230–234. Garcia, A. R., A. B. Batal, and N. M. Dale. 2007. A comparison of methods to determine amino acid digestibility of feed ingredients for chickens. Poult. Sci. 86:94–101. Golian, A., L. D. Campbell, C. M. Nyachoti, H. Janmohammadi, and J. A. Davidson. 2007. Nutritive value of an extruded blend of canola seed and pea (Enermax) for poultry. Can. J. Anim. Sci. 87:115–120. Golian, A., W. Guenter, D. Hoehler, H. Jahanian, and C. M. Nyachoti. 2008. Comparison of various methods for endogenous ileal amino acid flow determination in broiler chickens. Poult. Sci. 87:706–712. Heartland Lysine. 1996. Digestibility of Essential Amino Acids for Poultry and Swine. Version 3.3. Heartland Lysine Inc., Chicago, IL. Jeunink, J., and J. C. Cheftel. 1979. Chemical and physicochemical changes in field bean and soybean proteins texturized by extrusion. J. Food Sci. 44:1322–1325. Johnston, J., and C. N. Coon. 1979. A comparison of six protein quality assays using commercially available protein meals. Poult. Sci. 58:919–927. Keegan, T. P., J. M. DeRouchey, J. L. Nelssen, M. D. Tokach, R. D. Goodband, and S. S. Dritz. 2004. The effects of poultry meal source and ash level on nursery pig performance. J. Anim. Sci. 82:2750–2756. Kiarie, E., and C. M. Nyachoti. 2007. Ileal digestibility of amino acids in co-extruded pea and full fat canola for growing pigs. Anim. Feed Sci. Technol. 139:40–51. Lemme, A., V. Ravindran, and W. L. Bryden. 2004. Ileal digestibility of amino acids in feed ingredients for broilers. World’s Poult. Sci. J. 60:423–437. Llames, C., and J. Fontaine. 1994. Determination of amino acids in feeds: Collaborative study. J. AOAC Int. 77:1362–1402. Moran, E. T., J. D. Summers, and S. J. Slinger. 1966. Keratin as a source of protein for the growing chick. 1. Amino acid imbalance as the cause for the inferior performance of feather meal and the
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Key words: standardized ileal digestibility, apparent ileal digestibility, amino acid, broiler, processed feedstuff 2010 Poultry Science 89:2626–2633 doi:10.3382/ps.2010-00757
INTRODUCTION There is a wide range of feedstuffs used to supply protein and amino acids (AA) in poultry diets. The contents of AA in these feedstuffs that is available to the bird varies widely, especially in those ingredients that have undergone further processing or are generated as by-products of other industries (NRC, 1994). To optimize the utilization of such ingredients in practical poultry feed formulation, it is critical to characterize their available AA. However, because of the difficulties associated with the routine determination of AA availability, ileal digestibility measurements have been suggested as reasonable estimates of availability (Lemme et al., 2004). Although AA digestibility values for most poultry feedstuffs have been reported, the majority of ©2010 Poultry Science Association Inc. Received March 8, 2010. Accepted June 7, 2010. 1 Corresponding author: [email protected]
these estimates have been determined at the excreta level using the adult rooster assay (Parsons, 1991; NRC, 1994; Rhone-Poulenc, 1995; Heartland Lysine, 1996). Although digestibility estimates from adult rooster assays are widely applied to all classes of poultry diet formulations, criticisms have arisen from the fact that crop intubation is not a normal feeding pattern, and estimations carried out in adult, physiologically mature birds might not reflect the digestive capabilities of younger chickens (Ravindran et al., 1999; Lemme et al., 2004). An alternative to the precision-fed rooster assay is to determine digestibility estimates at the ileal level using the broiler chicken (Lemme et al., 2004). Currently, because this is a newer assay, there is a lack of data on the ileal AA digestibility for many feedstuffs. Where data do exist, most have been reported based on apparent ileal digestibility (AID) as opposed to standardized ileal digestibility (SID) estimates. It has been suggested that SID estimates should be used in formulating
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ABSTRACT Ileal digestibility of amino acids (AA) in dry-extruded expelled soybean meal (DESBM), coextruded canola seed-pea blend (ECSP, 50:50 wt/wt basis), poultry by-product meal (PBPM), and feather meal (FM) were determined in broiler chicks. For each ingredient, 5 samples each collected on different occasions were evaluated. Birds (n = 180 for each sample) were fed a commercial starter diet from d 1 to 15 of age followed by the test diets from d 15 to 21. Dry-extruded expelled soybean meal, ECSP, PBPM, and FM were included in the test diets at 95.3, 95.3, 38.4, and 28.4%, respectively, as the sole source of AA and balanced for minerals and vitamins. Chromic oxide (0.3%) was included in all diets as a digestibility marker. Each diet (5 per ingredient) was randomly assigned to 6 replicate cages, each with 6 birds. On d 21, birds were killed to collect ileal digesta for determining the apparent ileal AA digestibility on cage basis. The standardized
AMINO ACID DIGESTIBILITY IN PROCESSED FEEDS FOR BROILERS
MATERIALS AND METHODS Diets Five samples each of DESBM (Jordan Mills Inc., Delmar Commodities Ltd., Winkler, Manitoba, Canada), ECSP (EXP Feeds Inc., Shoal Lake, Manitoba, Canada), PBPM, and FM (Rothsay’s rendering plant, Win-
nipeg, Manitoba, Canada) were obtained from 5 different processing days. Thus, within feedstuff, 5 test diets were made each for each sampling-processing day. Each test diet contained a DESBM, ECSP, FM, or PBPM sample at 95.3, 95.3, 38.4, and 28.4%, respectively, as the sole source of protein and AA. Dextrose and canola oil were added in the PBPM (51.2 and 1.4%, respectively) and FM (59.5 and 3.1%, respectively) for palatability. Additionally, Solkafloc (MP Biochemicals, Solon, OH) was included at 3% in PBPM and FM test diets as a source of fiber. All test diets were balanced for mineral and vitamin levels to meet NRC (1994) requirement recommendations and contained chromic oxide (0.3%) as a digestibility marker.
Birds and Experimental Conduct The experimental protocol was reviewed and approved by the Animal Care Protocol Management and Review Committee of the University of Manitoba. Birds were cared for according to the guidelines of the Canadian Council on Animal Care (1993). One hundred eighty broiler chickens were used to assay each sample in 3 separate experiments, one for each feedstuff except for PBPM and FM samples, which were assayed together. The chicks were obtained from a local hatchery (Carlton Hatchery, Grunthal, Manitoba, Canada) and housed in Petersime battery brooders (Petersime Incubator Co., Gettysburg, OH) in a room with continuous fluorescent lighting. Room temperature was maintained at 32, 28, and 24°C during wk 1, 2, and 3, respectively. From d 1 to 14, birds were fed a commercial chick starter diet (FeedRite, Ridley Inc., Winnipeg, Manitoba, Canada) in crumble form (2,713 kcal/kg of AME, 20.8% CP, 0.96% total Lys, 0.4% total Met, 0.8% TSAA, 0.53% available P, 0.97% Ca, and phytase at 500 phytase units/kg). On d 14, birds were fasted for 3 h, weighed, and distributed 6 birds/ cage based on BW. Within a feedstuff, 6 replicate cages were randomly assigned to each of the 5 test diets and fed from d 15 to 21. Birds had ad libitum access to feed and water throughout the study period. On d 21, birds were killed by cervical dislocation and the digesta from the ileum (from Meckel’s diverticulum to a point 4 cm proximal to the ileocecal junction) were collected by gently squeezing the contents of the ileum into sample bags (Bandegan et al., 2009). Digesta from birds within a cage were pooled into 1 bag and frozen immediately after collection and subsequently freeze-dried. The dried ileal digesta were stored in airtight bags at −4°C until required for chemical analysis.
Chemical Analysis Raw feed ingredients, test diets, and digesta samples were finely ground using a coffee grinder (CBG5 Smart Grind, Applica Consumer Products Inc., Shelton, CT). Dry matter was determined according to AOAC (1990, method 925.09) and CP (N × 6.25) was determined by
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poultry diets because these are likely more additive in a mixture of feedstuffs compared with AID estimates (Angkanaporn et al., 1996). Furthermore, formulating broiler diets based on SID AA estimates results in rations that more closely match the birds’ requirements and reduce excess nutrients (Adedokun et al., 2007). Corn and soybean meal prices have been at record levels and when the prices of these basic ingredients are high, the use of alternative ingredients such as animal by-products and ingredients resulting from novel processing techniques such as dry-extruded soybean meal (DESBM) and extruded canola seed-pea blend (ECSP; 50:50 wt/wt) in broiler feed formulations becomes economically attractive. However, good nutritional information, especially regarding the available AA contents, is lacking. There has been a long history of use of poultry byproduct meal (PBPM) and feather meal (FM) in the poultry industry worldwide. However, the wide variation in digestible AA in these by-products, which primarily depends on the processing system, is often of great concern (NRC, 1994; Wang and Parsons, 1997). As a consequence, there have been some concerted efforts by renderers to improve the quality of their ingredients and adapt to standard regulations and manufacturing practices accordingly (Prokop, 1996; Keegan et al., 2004). There are only a few studies on the SID of AA in PBPM and FM fed to broilers (Garcia et al., 2007). Extrusion processing followed by expelling is a relatively recent technology developed for soybean meal processing. This technology has been adopted as an alternative means of producing soybean meal and other oilseed meal and oils for human consumption or the livestock industry, or both (Webster et al., 2003). The extruder-expeller process results in a product (DESBM) that has a higher fat content compared with solventextracted soybean meal (Webster et al., 2003; Opapeju et al., 2006). A co-extruded blend of canola seed and pea (50:50 wt/wt) has been evaluated as a potential high-energy and protein ingredient for poultry and swine in Western Canada (Golian et al., 2007; Kiarie and Nyachoti, 2007). Previous studies in our laboratory reported AA digestibility in DESBM and ECSP fed to roosters (Opapeju et al., 2006; Golian et al., 2007). However, reports regarding SID of AA in DESBM and ECSP fed to broilers are very limited. Thus, this study was conducted to determine the SID estimates of protein and AA and their associated CV in DESBM, ECSP, PBPM, and FM for broilers.
2627
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Bandegan et al.
434; Trp, 71; Val, 270; Ala, 217; Asp, 430; Cys, 143; Glu, 492; Gly, 245; Pro, 289; and Ser, 343.
Statistical Analysis The data for digestibility estimates of the samples were analyzed using the GLM procedure of SAS Institute (1990) as a completely randomized design. The nested procedure was applied to further analyze the random feed samples and bird-cage subsampling effects on the total variation observed. For a better demonstration of variability, the components of total CV associated with the AID and SID estimates for each AA across different feed samples are included as variance due to the samples
(s ) 2 s
and cages within samples
(s ). 2 e
RESULTS AND DISCUSSION
Digestibility Calculation The AID coefficient of AA was calculated as described by Bandegan et al. (2009). The SID coefficients of AA were calculated as follows: SID% = AID + [(basal IAAend/AAdiet) × 100], where IAAend = basal ileal endogenous AA loss. Basal endogenous loss estimates (mg/kg of DM intake) previously determined by Golian et al. (2008) using a N-free diet were used to calculate the SID values, and those estimates were as follows: CP, 4,365; Arg, 203; His, 91; Ile, 200; Leu, 298; Lys, 173; Met, 65; Phe, 420; Thr,
Crude protein and AA composition of DESBM, ECSP, PBPM, and FM are presented in Tables 1 and 2. The CP and AA composition of DESBM and ECSP compare well with previously published values (Woodworth et al., 2001; Opapeju et al., 2006; Golian et al., 2007). Among the indispensable AA content, Met and His ranked lowest, whereas Leu, Arg, and Lys ranked highest in both the DESBM and ECSP samples. Previous reports indicated that extrusion decreased the content of some AA including His, Met, and Cys in peas, soybean meal, and field beans (Jeunink and Cheftel, 1979; Cheftel, 1986; Prudencio-Ferreira and Areas, 1993; Alonso et al., 2000). A comparison between raw
Table 1. Crude protein and amino acid (AA) composition (%) of DESBM and ECSP samples (DM basis)1 DESBM (n = 5) Item DM CP Indispensable AA Arg His Ile Leu Lys Met TSAA Phe Thr Val Dispensable AA Ala Asp Cys Glu Gly Pro Ser
ECSP (n = 5)
Range
Mean
CV%2
92.3 to 93.9 44.6 to 46.7
93.3 45.8 3.24 1.16 2.04 3.43 2.81 0.67 1.38 2.26 1.82 2.15 1.96 5.18 0.71 8.04 1.93 2.14 2.32
0.7 1.9 1.4 2.0 1.3 1.6 1.9 1.3 1.6 2.0 1.8 1.2 1.5 1.8 2.0 1.9 1.6 1.7 1.9
3.19 1.14 2.01 3.37 2.75 0.66 1.37 2.21 1.80 2.12
to to to to to to to to to to
3.31 1.20 2.07 3.49 2.88 0.68 1.42 2.32 1.85 2.18
1.92 5.08 0.70 7.90 1.90 2.09 2.27
to to to to to to to
1.99 5.28 0.74 8.17 1.96 2.19 2.36
Range
Mean
CV%
92.9 to 94.6 23.7 to 24.2 1.52 to 1.61 0.55 to 0.59 0.94 to 0.98 1.64 to 1.70 1.28 to 1.37 0.34 to 0.39 0.76 to 0.85 1.03 to 1.10 0.94 to 0.96 1.12 to 1.20 1.00 to 1.04 2.02 to 2.21 0.42 to 0.47 3.83 to 4.01 1.03 to 1.08 1.08 to 1.17 1.05 to 1.13
93.5 24.0 1.58 0.57 0.96 1.68 1.34 0.37 0.81 1.08 0.95 1.16 1.02 2.14 0.44 3.90 1.06 1.11 1.10
0.7 0.7 2.3 2.5 2.2 1.4 2.8 4.8 4.8 2.4 1.1 2.4 1.6 3.6 5.0 1.8 1.6 3.1 2.9
1Samples of each ingredient collected at 5 different processing days to constitute 5 independent assay samples. DESBM = dry-extruded soybean meal; ECSP = extruded canola seed-pea blend 50:50 wt/wt. 2Coefficient of variation among different samples.
Downloaded from http://ps.oxfordjournals.org/ at University of Maryland on February 5, 2015
the combustion (method 990.03, AOAC, 1990) using a combustion analyzer (model CNS-2000, Leco Corp., St. Joseph, MI) and EDTA as a calibration standard. Amino acid concentrations were determined by Evonik Industries (Hanau-Wolfgang, Germany) using ion-exchange chromatography with postcolumn derivatization with ninhydrin (Llames and Fontaine, 1994). Sulfur AA (Met and Cys) were first oxidized with performic acid, which was subsequently neutralized with sodium metabisulfite (Commission Directive, 1998). Amino acid concentrations were quantified with the internal standard method by measuring the absorption of reaction products with ninhydrin at 570 nm. Chromium was analyzed, after the samples were ashed at 600°C for 12 h in a muffle furnace, using inductively coupled plasma mass spectrometry (ICP-AES Vista, Varian, Palo Alto, CA) according to the method of AOAC (2005, method 985.01).
2629
AMINO ACID DIGESTIBILITY IN PROCESSED FEEDS FOR BROILERS Table 2. Crude protein and amino acid (AA) composition (%) of PBPM and FM samples (DM basis)1 PBPM (n = 5) Mean
CV%2
96.5 to 97.0 61.6 to 63.5 4.04 to 4.16 1.25 to 1.34 2.03 to 2.13 4.02 to 4.18 3.53 to 3.68 1.05 to 1.09 1.54 to 1.62 2.24 to 2.32 2.16 to 2.24 2.70 to 2.86 4.16 to 4.28 4.76 to 4.96 0.48 to 0.53 7.60 to 7.90 6.53 to 6.63 3.94 to 4.08 2.32 to 2.44
96.8 62.6 4.11 1.29 2.08 4.07 3.59 1.07 1.58 2.28 2.20 2.78 4.21 4.85 0.51 7.74 6.57 3.99 2.37
0.19 1.1 1.2 3.1 1.8 2.0 1.8 1.5 2.0 1.6 1.7 2.2 1.2 1.6 3.5 1.5 0.6 1.4 2.2
Range
91.8 to 95.6 88.7 to 98.3 6.04 to 6.69 0.69 to 0.76 4.09 to 4.67 6.96 to 7.80 1.89 to 2.14 0.59 to 0.64 4.47 to 5.10 4.14 to 4.86 3.99 to 4.44 6.22 to 7.37 3.89 to 4.35 5.98 to 6.61 3.84 to 4.51 9.40 to 10.13 6.82 to 7.69 8.11 to 9.13 9.25 to 10.93
Mean
CV%
93.8 95.0 6.37 0.74 4.40 7.41 1.98 0.61 4.72 4.53 4.24 6.82 4.14 6.30 4.11 9.79 7.26 8.60 10.24
1.65 4.1 4.5 4.0 6.2 5.4 5.2 3.5 6.7 7.4 4.8 7.6 4.8 4.7 8.1 3.7 5.4 6.5 7.1
1Samples of each ingredient collected at 5 different processing days to constitute 5 independent assay samples. PBPM = poultry by-product meal; FM = feather meal. 2Coefficient of variation among different samples.
Table 3. Apparent ileal digestibility coefficients and their associated CV determined in chicks fed DESBM and ECSP samples1 DESBM
ECSP Variance components3
Item
Range
CP Indispensable AA4 Arg His Ile Leu Lys Met TSAA Phe Thr Val Dispensable AA Ala Asp Cys Glu Gly Pro Ser 1Five
Mean
CV%2
Between
Within
82.1 to 89.2
86.0
4.2
58.7
41.3
88.8 85.0 84.0 84.2 86.7 88.0 82.0 86.2 78.4 82.1
to to to to to to to to to to
93.6 92.0 90.7 90.6 91.6 92.6 86.8 91.9 85.5 89.0
91.4 89.1 87.3 87.6 89.4 90.5 84.3 89.1 82.6 85.5
2.7 3.2 3.9 3.7 2.9 2.9 4.6 3.3 4.8 4.1
49.1 44.3 52.1 57.2 44.2 45.1 39.1 55.2 50.5 53.2
50.9 55.7 47.9 42.8 55.8 54.9 60.9 44.8 49.5 46.8
83.2 81.9 72.1 87.2 79.2 83.1 81.3
to to to to to to to
89.1 89.0 81.1 92.3 86.0 89.0 87.7
86.5 85.8 78.0 90.0 83.1 86.4 85.3
3.6 4.1 6.9 3.1 4.3 3.7 4.0
53.0 46.5 36.1 41.2 46.3 46.2 53.9
47.0 53.5 63.9 58.8 53.7 53.8 46.1
Variance components
Range
Mean
CV%
Between
Within
70.3 to 73.3
71.5
2.3
40.8
59.2
82.2 72.6 71.7 73.9 76.1 79.4 72.9 73.3 66.6 70.3
to to to to to to to to to to
84.4 76.6 74.1 76.3 78.8 83.5 76.2 76.1 70.3 73.1
83.3 75.2 72.8 74.9 77.4 81.6 74.5 74.2 67.8 71.6
1.5 3.8 2.3 2.0 2.1 2.6 2.5 2.7 3.1 2.4
39.6 21.5 23.1 30.4 40.2 38.0 36.6 21.5 39.3 40.7
60.4 78.5 76.9 69.6 59.8 62.0 63.4 78.5 60.7 59.3
74.0 72.1 67.4 79.8 70.0 71.1 68.5
to to to to to to to
76.2 75.5 69.4 82.0 72.8 73.4 71.8
74.8 73.4 68.4 80.8 71.2 71.9 69.5
2.0 2.5 2.7 1.6 2.4 2.0 2.9
27.2 44.6 12.3 34.2 32.1 26.3 30.4
72.8 55.4 87.7 65.8 67.9 73.7 69.6
( )
samples of each feed ingredient were assayed in 6 replicate cages with 6 birds in each and variance components for samples ss2 and cages
( )
within samples se2 were determined. DESBM = dry-extruded soybean meal; ECSP = extruded canola seed-pea blend 50:50 wt/wt. 2Total
CV: CV% =
3Percentage 4AA
ss2 + se2 y
´ 100%, where y = mean.
(
)
(
)
contribution to the total variation calculated as ss2 / ss2 + se2 and se2 / ss2 + se2 for samples and cages within samples, respectively.
= amino acid.
Downloaded from http://ps.oxfordjournals.org/ at University of Maryland on February 5, 2015
Range
Item DM CP Indispensable AA Arg His Ile Leu Lys Met TSAA Phe Thr Val Dispensable AA Ala Asp Cys Glu Gly Pro Ser
FM (n = 5)
2630
Bandegan et al.
Table 4. Standardized ileal digestibility coefficients and their associated CV determined in chicks fed DESBM and ECSP samples1 DESBM
ECSP Variance components3
Mean
CV%2
Between
Within
Range
Mean
CV%
Between
Within
84.4 to 91.4
88.2
4.0
42.3
57.7
72.2 to 75.2
73.4
2.3
40.4
59.6
90.3 86.7 86.4 86.3 88.1 90.1 83.4 93.2 84.0 85.1
to to to to to to to to to to
95.1 92.0 92.9 92.6 93.1 94.7 90.2 98.9 91.1 91.9
92.9 89.6 89.5 89.6 90.8 92.5 87.5 95.9 88.0 88.4
2.7 3.2 3.7 3.6 2.8 2.9 4.5 3.1 4.4 4.0
51.1 55.7 48.2 43.0 55.8 54.6 60.9 45.1 49.8 47.0
48.9 44.3 51.8 57.0 44.2 45.4 39.1 54.9 50.2 53.0
83.7 74.2 74.0 75.8 77.5 81.3 75.6 80.2 71.5 72.8
to to to to to to to to to to
85.7 78.3 76.4 78.2 80.2 85.2 78.8 82.9 75.2 75.7
84.7 76.8 75.0 76.8 78.8 83.4 77.1 80.9 72.7 74.1
1.5 3.7 2.2 1.9 2.0 2.4 2.4 2.4 2.9 2.3
37.0 20.9 22.1 30.2 38.7 35.5 35.1 17.7 39.7 39.5
63.0 79.1 77.9 69.8 61.3 64.5 64.9 82.3 60.3 60.5
85.7 83.9 76.7 88.6 82.2 86.2 84.8
to to to to to to to
91.7 90.9 85.6 93.8 89.0 92.1 91.2
89.0 87.7 82.5 91.4 86.0 89.4 88.6
3.5 4.0 6.5 3.1 4.2 3.6 3.8
46.9 53.7 64.5 58.8 53.7 54.3 46.8
53.1 46.3 35.5 41.2 46.3 45.7 53.2
76.3 74.3 70.8 81.2 72.5 73.6 71.9
to to to to to to to
78.5 77.7 72.9 83.4 75.3 76.0 75.2
77.1 75.5 71.8 82.1 73.6 74.4 72.9
1.9 2.4 2.6 1.5 2.4 2.0 2.8
27.4 43.4 13.3 33.8 32.1 27.0 30.4
72.6 56.6 86.7 66.2 67.9 73.0 69.6
1Five
( )
samples of each feed ingredient (n = 5) were assayed in 6 replicate cages with 6 birds in each and variance components for samples ss2 and
cages within samples 2Total
CV: CV% =
3Percentage 4AA
( ) were determined. DESBM = dry-extruded soybean meal; ECSP = extruded canola seed-pea blend 50:50 wt/wt. se2
ss2 + se2 y
´ 100%, where y = mean.
(
)
(
)
contribution to the total variation calculated as ss2 / ss2 + se2 and se2 / ss2 + se2 for samples and cages within samples, respectively.
= amino acid.
and processed products for the effect of extrusion on AA content was not made in this study; however, in a comparison between the raw and extruded canola seed and pea blend, Golian et al. (2007) concluded that extrusion decreased Glu and Gly contents. The CV for AA ranged from 1.2% (Val) to 2.0% (His, Phe, and Cys) and 1.1% (Thr) to 5.0% (Met and Cys) for DESBM and ECSP, respectively. The CP and AA composition of PBPM and FM samples compared well with previously published values (Daghir, 1975; Johnston and Coon, 1979; Baker et al., 1981; Papadopoulos et al., 1986; Wang and Parsons, 1998; Ravindran et al., 2005). The AA profile of PBPM and FM showed a somewhat similar trend, with Met and His ranking the lowest. On the other hand, Leu and Arg in PBPM and Leu and Val in FM ranked the highest. Generally, a wider CV range (3.5 to 8.1%) was observed for AA profile in FM than in PBPM (0.6 to 3.5%). Cysteine was the most variable AA in both PBPM (3.5%) and FM (8.1%). It has been shown that processing conditions have a substantial effect on reducing Cys, Met, Lys, and His contents in FM (Moran et al., 1966; Eggum, 1970; Papadopoulos et al., 1986). The AID of AA in DESBM and ECSP ranged from 78% (Cys) to 91% (Arg) and 68% (Cys) to 83% (Arg), respectively (Table 3), whereas the corresponding SID values ranged from 83% (Cys) to 96% (Phe) and 72%
(Cys) to 85% (Arg), respectively (Table 4). Among the indispensible AA, Thr had the least AID and SID estimates in both DESBM and ECSP. Threonine is a major AA in endogenous secretions, which may partly explain the reason for its lower digestibility (Siriwan et al., 1993; Ravindran and Hendriks, 2004a). The highest CV for SID estimates was observed for Cys (6.9%) and His (3.8%) in DESBM and ECSP, respectively, which on further partitioning revealed that 36 and 22% of the CV was due to the variation between the samples, respectively. This means that the highest variation observed for SID estimates in DESBM and ECSP was more affected by the assay conditions than the feed samples. Estimates for the SID AA in DESBM and ECSP in broilers have not been reported in the literature. Nevertheless, the SID values determined in this study were lower than the true AA digestibility values determined in cecectomized roosters with different batches of DESBM (Opapeju et al., 2006) and for ECSP (Golian et al., 2007). Similarly, Garcia et al. (2007) reported lower digestible AA estimates for soybean meal in broilers than in roosters. The AID results show a shorter AA digestibility range for PBPM (51 to 81%) compared with FM (39 to 74%) (Table 5). Cysteine (51%) and Asp (39%) were the least digestible AA in PBPM and FM, respectively; however, Thr (70%) in PBPM and Lys and Thr (56%)
Downloaded from http://ps.oxfordjournals.org/ at University of Maryland on February 5, 2015
Range
Item CP Indispensable AA4 Arg His Ile Leu Lys Met TSAA Phe Thr Val Dispensable AA Ala Asp Cys Glu Gly Pro Ser
Variance components
2631
AMINO ACID DIGESTIBILITY IN PROCESSED FEEDS FOR BROILERS
Table 5. Apparent ileal amino acid (AA) digestibility coefficients and their associated CV determined in chicks fed PBPM and FM samples1 PBPM
FM Variance components3
Item
Range
1Five
CV%2
Between
Within
Range
Mean
CV%
Between
Within
74.2 66.1 65.9 69.2 67.8 73.0 60.6 69.8 59.4 66.6
to to to to to to to to to to
84.9 80.9 80.5 82.7 81.9 84.5 76.7 83.3 76.2 80.8
81.2 75.5 75.2 77.8 76.7 80.3 70.9 78.2 70.2 75.7
5.7 8.0 8.0 7.1 7.5 6.0 9.4 7.1 10.0 7.8
75.2 83.3 80.8 81.5 82.9 79.1 80.9 79.7 81.3 80.3
24.8 16.7 19.2 18.5 17.1 20.9 19.1 20.3 18.7 19.7
75.2 52.3 70.9 65.8 51.5 63.3 43.4 69.4 48.8 66.5
to to to to to to to to to to
66.6 63.2 78.8 75.7 60.5 71.0 59.7 78.6 63.0 76.6
70.5 57.7 74.1 70.0 56.4 67.9 53.1 73.3 56.4 71.3
8.6 10.7 7.6 9.4 10.4 7.0 18.6 8.3 13.9 9.6
3.7 18.2 3.0 6.4 12.6 16.2 20.4 5.9 24.1 6.6
96.3 81.8 97.0 93.6 87.4 83.8 79.6 94.1 75.9 93.4
71.1 44.7 34.0 66.6 66.4 61.4 57.3
to to to to to to to
83.2 67.6 59.8 80.8 80.6 76.8 74.9
78.9 59.0 50.6 75.8 75.7 71.3 68.4
6.4 15.7 21.5 7.8 8.4 9.1 10.6
78.8 82.8 77.2 79.4 67.9 78.5 81.1
21.2 17.2 22.8 20.6 32.1 21.5 18.9
63.9 26.6 38.9 67.8 62.7 52.3 58.5
to to to to to to to
74.3 48.3 58.0 55.2 74.4 66.4 71.5
68.1 39.4 50.4 62.3 68.7 59.9 65.2
10.3 27.7 22.5 12.7 11.1 13.2 11.3
5.0 40.8 23.9 14.0 9.0 21.7 19.2
95.0 59.2 76.1 86.0 91.0 78.3 80.8
( )
samples of each feed ingredient were assayed in 6 replicate cages with 6 birds in each and variance components for samples ss2 and cages
within samples 2Total
( ) were determined. PBPM = poultry by-product meal; FM = feather meal. se2
CV: CV% =
3Percentage
ss2 + se2 y
´ 100%, where y = mean.
(
)
(
)
contribution to the total variation calculated as ss2 / ss2 + se2 and se2 / ss2 + se2 for samples and cages within samples, respectively.
in FM were the least digestible among the indispensible AA. In contrast, Arg (81%) in PBPM and Ile (74%) in FM were the most digestible indispensable AA. Other than change in ranking of AA digestibility, the SID values (Table 6) followed a similar trend for all AA as those of AID. Specifically, SID of Cys (57%) in PBPM and Asp (42%) in FM were found to be the least digestible, whereas Phe was the most digestible in both. Comparing the SID values of both FM and PBPM shows that Lys was among the least digestible AA in FM (60%), whereas it was better digested in PBPM (78%). Results published for the average true AA digestibility estimates for FM and PBPM in NRC (1994) are somewhat higher than those found in the present study. This could be partly explained by the fact that the sample source, methodology, and age of the birds used in experiments can affect digestibility results from different assays (Ten Doeschate et al., 1993; Ravindran and Hendriks, 2004b; Garcia et al., 2007). As mentioned earlier, digestibility estimates of processed products are very variable and this might be due to the feed samples used or assay condition, yet the pooled variation reported in the literature lacks the transparency required to explain them separately. Because total variation observed in estimating AID and SID values is affected by both the feed samples (between) and assay condition (within), it is of benefit to separate the total variance into these components to
demonstrate their contribution separately. Overall, the range of CV values associated with the AID estimates of AA in PBPM was shorter (5.7 to 22%) and was mostly due to the feed sample, whereas those of FM varied more (7.0 to 28%) and were mainly due to the assay condition (cage-to-cage differences). The CV associated with AID estimates of Cys and Asp was the most variable of all AA in both PBPM and FM. Low Met, Lys, and His contents together with their lower digestibility in FM has been reported before (Moran et al., 1966; Morris and Balloun, 1973; Baker et al., 1981). It has been shown that AA imbalance in feed can reduce appetite (Peng and Harper, 1970). If the CV associated with AID values for each FM sample is because of depressed appetite and varied feed intake of the birds, then the total CV of each AA determined in FM is expected to be affected by a within-sample component. Therefore, as it was expected, a wider variation of the total CV was due to cage-to-cage difference (within) than the samples themselves (between). On the contrary, PBPM is a more digestible feed than FM and it was shown that mixing PBPM with FM resulted in superior bird performance than using FM alone (Bhargava and O’Neil, 1975; Daghir, 1975). Thus, the total variation observed for each AA estimate in PBPM was more affected by the samples (between) than the assay condition (within).
Downloaded from http://ps.oxfordjournals.org/ at University of Maryland on February 5, 2015
Indispensable AA Arg His Ile Leu Lys Met TSAA Phe Thr Val Dispensable AA Ala Asp Cys Glu Gly Pro Ser
Mean
Variance components
2632
Bandegan et al.
Table 6. Standardized ileal amino acid (AA) digestibility coefficients and their associated CV determined in chicks fed PBPM and FM samples1 PBPM
FM Variance components3
Item
Range
1Five
CV%2
Between
Within
Range
Mean
CV%
Between
Within
75.5 67.8 68.5 71.1 69.1 74.4 79.7 77.5 64.6 69.1
to to to to to to to to to to
86.2 82.5 83.0 84.5 83.1 85.9 63.8 90.6 81.2 83.3
82.5 77.1 77.7 79.7 78.0 81.7 74.1 85.8 75.3 78.2
5.6 7.8 7.7 6.9 7.4 5.9 9.0 6.3 9.2 7.5
75.0 83.1 80.6 81.3 82.8 79.1 80.6 78.8 80.9 80.1
25.0 16.9 19.4 18.7 17.2 20.9 19.4 21.2 19.1 19.9
67.7 55.7 72.5 67.2 54.3 66.2 44.9 74.7 52.3 68.0
to to to to to to to to to to
76.3 66.9 80.3 77.0 63.7 74.2 61.2 83.3 66.4 77.9
71.6 61.3 75.7 71.4 59.5 71.0 54.7 78.4 59.9 72.7
8.4 10.2 7.4 9.2 10.0 6.8 18.1 7.7 13.0 9.4
3.2 19.9 2.4 5.8 15.3 18.3 20.4 3.4 23.2 5.9
96.8 80.1 97.6 94.2 84.7 81.7 79.6 96.6 76.8 94.1
72.4 47.0 41.4 68.3 67.3 63.2 61.1
to to to to to to to
84.4 69.8 66.5 82.4 81.5 78.5 78.4
80.2 61.3 57.6 77.4 76.7 73.1 72.1
6.3 15.1 18.5 7.7 8.3 8.8 9.9
78.7 82.7 76.4 79.3 67.8 78.4 80.7
21.3 17.3 23.6 20.7 32.2 21.6 19.3
65.7 29.0 40.1 56.9 63.9 53.5 59.7
to to to to to to to
76.0 50.6 59.3 69.5 75.5 67.4 72.5
69.9 41.7 51.6 64.1 69.8 61.0 66.3
10.1 26.1 21.9 12.3 10.9 12.9 11.1
4.5 40.4 23.8 13.8 8.6 21.1 18.5
95.5 59.6 76.2 86.2 91.4 78.9 81.5
( )
samples of each feed ingredient were assayed in 6 replicate cages with 6 birds in each and variance components for samples ss2 and cages
within samples 2Total
( ) were determined. PBPM = poultry by-product meal; FM = feather meal. se2
CV: CV% =
3Percentage
ss2 + se2 y
´ 100%, where y = mean.
(
)
(
)
contribution to the total variation calculated as ss2 / ss2 + se2 and se2 / ss2 + se2 for samples and cages within samples, respectively.
For effective diet formulation and optimum use of feedstuff to meet the requirements, it is important that the digestibility values be relevant to the age of the bird to which the diet is being fed. Furthermore, in determining these digestibility values, it is also important to account for and report the variation observed for the feed and methodology separately. A large body of AA digestibility data in the literature has been created (Parsons, 1991; NRC, 1994; Rhone-Poulenc, 1995; Heartland Lysine, 1996) using the cecectomized rooster. Potential drawbacks to this data are the application to broiler diets and that they do not provide a clear expression of variation associated with each of the observations within the assay condition. As such, the AA digestibilities determined at the ileal level are more accurate than digestibilities determined at the excreta level of intact noncecectomized birds (Ravindran et al., 1999; Lemme et al., 2004). Furthermore, it is now clear that ileal AA digestibility values are affected by the methodology and age of the birds used (Ten Doeschate et al., 1993; Ravindran and Hendriks, 2004b; Garcia et al., 2007). Moreover, the SID values as opposed to AID values are better estimates of the AA availability in feedstuff and when used in a mixed diet they have been shown to be additive (Angkanaporn et al., 1996; Stein et al., 2005). Among the feed ingredients tested, DESBM was the most digestible with its SID AA values ranging from
83 to 93% for Cys and Phe, respectively. Poultry byproduct meal was more digestible with lesser variability compared with FM. A common point among the tested processed feeds was that they all had the heat-labile AA, including Lys, sulfur amino acids, and Gly ranked among the lowest SID values, whereas Phe was reported to be stable in thermal processing (Papadopoulos et al., 1986) and was rated as the most digestible AA of all, except in ECSP, in which Arg was the most digestible AA. The CV associated with the SID estimates of AA was higher in FM compared with ECSP, DESBM, and PBPM, with ECSP as the least variable of all. In both FM and PBPM, Asp and Cys estimates of SID were the most variable.
ACKNOWLEDGMENTS We thank Harry Muc (University of Manitoba) for his technical assistance. Funding for this study was provided by Evonik Degussa Corporation (Kennesaw, GA) and the Natural Sciences and Engineering Research Council of Canada (NSERC, Ottawa, Ontario, Canada).
REFERENCES Adedokun, S. A., C. M. Parsons, M. S. Lilburn, O. Adeola, and T. J. Applegate. 2007. Standardized ileal amino acid digestibility of meat and bone meal from different sources in broiler chicks
Downloaded from http://ps.oxfordjournals.org/ at University of Maryland on February 5, 2015
Indispensable AA Arg His Ile Leu Lys Met TSAA Phe Thr Val Dispensable AA Ala Asp Cys Glu Gly Pro Ser
Mean
CV (%) contribution
AMINO ACID DIGESTIBILITY IN PROCESSED FEEDS FOR BROILERS
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