INTRODUCTION To effectively use soybean meal (SBM) and meat

and bone meal (MBM), poultry nutritionists must have good nutritional information about these ingredi-ents. There is a dearth of information on standardized ileal amino acid digestibility (SIAAD) for many feed ingredients, particularly for a specific target or strain of bird.

Digestible amino acid (AA) values are considered to be the best measure of the AA value of ingredients (Rostagno et al., 1995); unfortunately the amount of digestible AA data that is available, particularly for some ingredients, is not very large and species specific. Although, most commercial nutritionists have adopted diet formulation on a digestible AA basis, a lack of suf-ficient information on SIAAD for different feed ingre-dients relative to strains of poultry still persists. Addi-

tionally, recent studies in our laboratory (Adedokun et al., 2009a) showed significant differences in AA digest-ibility of feed ingredients (corn, MBM, and dried dis-tillers grain with solubles) between broilers and laying hens. This difference raises an important question as to whether or not it makes sense both from the economic and environmental point of view, as AA digestibility values derived from adult roosters are routinely used for different strains and poultry species.

The digestibility, and thus availability, of nutrients and energy in MBM vary depending on the source and processing techniques (Parsons et al., 1997; Shirley and Parsons, 2000; Adedokun and Adeola, 2005a,b; Ade-dokun et al., 2007b). Studies in pigs (Adedokun and Adeola, 2005a; Olukosi and Adeola, 2009) and ducks (Adedokun and Adeola, 2005b) using 12 MBM samples showed that, although chemical compositions may play an important role in the ME values of MBM, the inter-actions among the different components of MBM may have significant influence on energy utilization.

Studies have shown that the AA digestibility of SBM may be affected by cultivation location, season, pro-cessing technique, and the level of antinutritional fac-

Standardized ileal amino acid digestibility of meat and bone meal and soybean meal in laying hens and broilers

S. A. Adedokun ,* P. Jaynes ,* M. E. Abd El-Hack ,† R. L. Payne ,‡ and T. J. Applegate *1

* Department of Animal Sciences, Purdue University, West Lafayette, IN 47907-2054; † Department of Poultry, Faculty of Agriculture, Zagazig Universtity, Zagazig 44111, Egypt; and ‡ Evonik Industries, Kennesaw, GA 30144

ABSTRACT The objective of this study was to deter-mine the standardized ileal amino acid digestibility (SIAAD) of 7 meat and bone meal (MBM) and 3 soy-bean meal (SBM) samples in broilers (Ross 708) and laying hens (Hy-line W36). All 10 feed ingredients were evaluated in 21-d-old broiler chickens and 30- or 50-wk-old laying hens. Standardization was accomplished by correcting for basal ileal endogenous amino acid losses using a nitrogen-free diet. Broilers were reared in cages from d 0 to 16 on a standard broiler starter diet ad-equate in all nutrients and energy; thereafter, they were allotted to treatments using a randomized complete de-sign with 6 replicate cages of 8 birds each. For the lay-ing hens, 6 replicate cages of 6 birds each (542 cm2/bird) were used. Each treatment diet, which was fed for 5 d, was semipurified, with MBM or SBM being the sole source of amino acids in each diet. Ileal endogenous

amino acid losses were not different between broilers and the 2 groups of laying hens. Meat and bone meal from different locations varied widely in digestibility. Broilers had higher (P < 0.05) SIAAD in 4 of the 7 MBM samples. In 2 of the 3 SBM samples, broilers had higher (P < 0.05) SIAAD for most of the nonessential amino acids. Generally, hens had 6.4 and 7.7% units less Met and Lys digestibility of all MBM samples af-ter standardization. Dry matter digestibility values of the SBM samples were higher (P < 0.05) in broilers. Likewise, broilers had 4.1 and 1.5% units more Met and Lys digestibility of all the SBM samples evaluated compared with those from laying hens. The results of these experiments suggest that differences exist in the digestive capabilities of laying hens and broilers, which indicates that species-specific nutrient digestibility val-ues or adjustments may be needed.

Key words: broiler , laying hen , meat and bone meal , soybean meal , standardized amino acid digestibility

2014 Poultry Science 93 :420–428http://dx.doi.org/ 10.3382/ps.2013-03495

Received July 16, 2013. Accepted October 13, 2013. 1 Corresponding author: applegt@purdue.edu

© 2014 Poultry Science Association Inc.

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tors, such as trypsin inhibitors, lectins, saponins, and oligosaccharides (Parsons, 1991; Frikha et al., 2012; Kim et al., 2012). Despite the fact that antinutritional factors can be inactivated during processing through heating (Liener, 1994), AA digestibility could be nega-tively affected if the heating condition is not optimal (Frikha et al., 2012).

Although data have been published on AA digest-ibility of some feed ingredients in poultry (Adedokun et al., 2007a,b, 2008), the need for more SIAAD data still exists. This would undoubtedly increase the reliability of the data as well as the confidence level of commercial nutritionists in using this information in diet formula-tion. Therefore, the objective of this research was to de-termine and compare SIAAD values of different MBM and SBM samples in broilers and laying hens and to continue to add to the publicly available data.

MATERIALS AND METHODS

Diet FormulationA total of 10 (7 MBM and 3 SBM) feed ingredi-

ents, sourced from Midwest and Mideast regions of the United States in 2010, were evaluated for SIAAD. Basal ileal endogenous amino acid (EAA) losses were determined using a nitrogen-free diet (NFD) method. Each of the 10 feed ingredients constituted an experi-mental diet, with each ingredient being the sole source of CP in a semipurified diet. Each diet was formulated to contain 20% CP (Table 1). Broilers and laying hens

were fed either a standard corn-soy-based starter diet or a regular laying hen diet that met or exceeded the NRC (1994) recommendations, respectively, before the feeding of the experimental diets. Each of the experi-mental diets contained 5 g/kg of chromic oxide as an indigestible marker. The same diet batch was fed to broilers and laying hens. Furthermore, the MBM diets (7) were evaluated in 252 thirty-week-old laying hens, whereas the SBM diets (3) were evaluated in 108 fifty-week-old laying hens. Analyzed sodium, crude fat, Ca, and P contents of the 7 MBM samples and the analyzed dietary AA and CP (N × 6.25) contents (DM basis) are reported in Tables 2 and 3, respectively.

Birds and HousingBirds were housed and raised, including bird care

and experimental procedures, in line with a protocol approved by Purdue University Animal Care and Use Committee. Experimental details of the broiler stud-ies are similar to those reported by Adedokun et al. (2007b). Briefly, all birds (broilers and laying hens) sampled in this study were on the respective feed ingre-dient diets and NFD for 5 consecutive days.

A total of 528 one-day-old broiler chicks (Ross 708) and 288 thirty-week-old and 144 fifty-week-old lay-ing hens (Hy-Line 36) were used in this study. For the broiler trial, each of the 11 experimental diets (10 feed ingredient-diets and 1 NFD) was fed to 6 replicate cag-es of 8 birds/cage in a completely randomized design. For the laying hens, 6 replicate cages of 6 birds/repli-

Table 1� Ingredient composition of experimental diets

Item, g/kg MBM 11 MBM 2 MBM 3 MBM 4 MBM 5 MBM 62 MBM 7 SBM3 NFD4

CP 473 536 524 502 503 559 504 460 0Ingredient Corn starch 446 496 488 471 471 512 472 0 179 Dextrose 0 0 0 0 0 0 0 444 640 Feed ingredient 424 374 382 399 399 358 398 442 0 NaHCO3 0 0 0 0 0 0 0 0 12 KCl 0 0 0 0 0 0 0 0 4 MgO 0 0 0 0 0 0 0 0 0.7 Solkafloc5 50 50 50 50 50 50 50 0 50 Soy oil 50 50 50 50 50 50 50 50 50 Vitamin-mineral premix6 5 5 5 5 5 5 5 5 5 Monocalcium phosphate 0 0 0 0 0 0 0 19 19 Choline chloride 0 0 0 0 0 0 0 3 2.5 Limestone 0 0 0 0 0 0 0 10 13 NaCl 0 0 0 0 0 0 0 2 0 Chromic oxide premix7 25 25 25 25 25 25 25 25 25 Total 1,000 1,000 1,000 1,000 1,000 1,000 1,000 1,000 1,000

1MBM = meat and bone meal.2Porcine meat and bone meal.3SBM = soybean meal. Levels of inclusion of the 3 SBM samples were the same in the experimental diets.4NFD = nitrogen-free diet.5Purified cellulose, International fiber corp., North Tonawanda, NY.6Provided per kilogram of diet: iron, 71.6 mg; copper, 11.0 mg; manganese, 178.7 mg; zinc, 178.7 mg; iodine, 3.0 mg; selenium, 0.4 mg; vitamin

A (retinyl acetate), 18,904.3 IU; vitamin D3 (cholecalciferol), 9,480.0 IU; vitamin E (dl-α-tocopheryl acetate), 63.0 IU; vitamin K activity, 6.4 mg; thiamine, 3.2 mg; riboflavin, 9.4 mg; pantothenic acid, 34.7 mg; niacin, 126.0 mg; pyridoxine, 4.7 mg; folic acid, 1.6 mg; biotin, 0.5 mg; vitamin B12, 35.4 µg; choline, 956.9 mg.

7Prepared by mixing 1 g of chromic oxide with 4 g of corn starch.

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cate (542 cm2/bird) were used. Diets containing MBM samples were fed to 30-wk-old laying hens and diets containing SBM were fed to 50-wk-old laying hens. The same set of diets and NFD were fed to the broiler chick-ens and laying hens. The NFD was fed to 48 broilers, 36 thirty-week-old, and 36 fifty-week-old laying hens.

Sampling and Ileal Digesta ProcessingBirds were euthanized using CO2 asphyxiation. Di-

gesta was collected from the entire ileum. The ileum was considered to be the portion of the small intestine from Meckel’s diverticulum to about 5 mm proximal to the ileo-cecal-colonic junction. Ileal digesta was flushed with distilled water from all birds within a cage (broiler) and adjacent 3 cages of 2 birds/cage (1 replicate of lay-ing hens) were pooled and frozen. Ileal digesta samples were stored at −20°C before samples were subsequently freeze dried. Freeze-dried samples were ground using a coffee grinder.

Chemical Analyses

Dry matter content was determined on ground diets and freeze-dried ileal digesta (0.5 g in duplicate) by drying the samples at 105°C for 24 h. Diets and ileal digesta were analyzed for AA contents by Evonik In-dustries (Hanau, Germany). Samples for AA analyses were hydrolyzed in 6 N HCl for 24 h at 110°C under N atmosphere. Performic acid oxidation was carried out before acid hydrolysis for Met and Cys analysis. (AOAC International, 2000; 982.30 E [a, b, c]). The AA in the hydrolysate was subsequently determined by HPLC af-ter postcolumn derivatization. Amino acid concentra-tions were not corrected for incomplete recovery result-ing from hydrolysis. Chromium and nitrogen in diets and ileal digesta and Ca, P, Na, nitrogen, and crude fat (CF) concentrations in MBM were determined. Chromium, Ca, and P concentrations were determined following nitric and perchloric acid wet-ash diges-tion (935.13, AOAC International, 2000). Chromium

Table 2� Analyzed nutrient composition of meat and bone meal (MBM) samples (on an as-is basis)

Item, % CP1 Sodium Calcium Phosphorus Crude fat2

MBM 1 47.3 0.78 10.08 4.58 8.32MBM 2 53.6 1.06 8.51 4.17 9.39MBM 3 52.4 0.75 7.99 3.81 13.19MBM 4 50.2 0.87 7.91 3.77 12.19MBM 5 50.3 0.58 12.14 5.57 10.41MBM 63 55.9 0.50 9.20 4.33 11.29MBM 7 50.4 0.57 10.05 4.65 9.63Average 51.44 0.73 9.41 4.41 10.63

1CP = nitrogen × 6.25.2Ether extract.3Porcine meat and bone meal.

Table 3� Analyzed amino acid contents of experimental diets (on an as-is basis)1

Item, % MBM 12 MBM 2 MBM 3 MBM 4 MBM 5 MBM 63 MBM 7 SBM 14 SBM 2 SBM 3

CP5 20.2 20.4 19.2 21.1 19.6 18.9 19.3 21.8 22.0 20.9DM 96.4 96.8 97.2 97.1 97.2 96.5 92.8 91.6 91.2 91.2Essential amino acid Arg 1.34 1.32 1.24 1.37 1.36 1.32 1.33 1.57 1.60 1.50 His 0.37 0.45 0.34 0.44 0.32 0.31 0.31 0.55 0.55 0.51 Ile 0.57 0.62 0.54 0.60 0.51 0.52 0.54 0.99 0.98 0.92 Leu 1.22 1.32 1.11 1.26 1.09 1.11 1.20 1.67 1.70 1.56 Lys 0.96 1.07 0.90 1.03 0.92 0.96 0.95 1.22 1.18 1.09 Met 0.28 0.29 0.26 0.29 0.26 0.26 0.26 0.29 0.27 0.27 Met + Cys 0.44 0.47 0.44 0.44 0.43 0.48 0.49 0.58 0.55 0.55 Phe 0.66 0.71 0.61 0.69 0.61 0.60 0.64 1.10 1.13 1.03 Thr 0.64 0.69 0.60 0.66 0.60 0.60 0.63 0.84 0.86 0.79 Val 0.81 0.88 0.76 0.85 0.75 0.76 0.82 1.03 1.03 0.96Nonessential amino acid Ala 1.48 1.45 1.35 1.50 1.47 1.37 1.38 0.93 0.95 0.87 Asp 1.49 1.57 1.38 1.55 1.40 1.40 1.42 2.54 2.50 2.30 Cys 0.16 0.18 0.18 0.15 0.17 0.21 0.24 0.30 0.28 0.28 Glu 2.43 2.52 2.19 2.49 2.25 2.31 2.28 3.91 4.00 3.72 Gly 2.63 2.38 2.42 2.65 2.88 2.57 2.51 0.93 0.94 0.88 Pro 1.50 1.40 1.36 1.50 1.57 1.46 1.41 1.05 1.07 1.00 Ser 0.76 0.78 0.70 0.74 0.73 0.76 0.77 1.06 1.11 0.99

1Amino acids were not detected in the nitrogen-free diet.2MBM = meat and bone meal.3Porcine meat and bone meal.4SBM = soybean meal.5CP = nitrogen × 6.25.

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and P concentrations were estimated from the diges-tion products by spectrophotometry (method 946.06, AOAC International, 2000) and absorbance read using a Dynex plate reader (Dynex Technologies Inc., Chan-tilly, VA). Calcium concentrations were determined by flame atomic absorption spectroscopy method. Calcium absorbance was read from the same digesta from which P was determined using a Varian Spectr.AA 220FS (Varian Australia Pty Ltd., Victoria, Australia). So-dium concentration in the MBM samples was also de-termined (AOAC International, 2000; method 976.25). Nitrogen was determined by the combustion method (model FP2000, Leco Corp., St. Joseph, MI; AOAC International 2000; method 990.03) with EDTA serving as the internal standard. Crude fat was determined by the ether extraction method (method 934.01; AOAC International, 2000). Except for AA, all other analyses were done in duplicate.

Calculations and Statistical AnalysisThe ileal EAA losses (index method) from each group

of bird was calculated as mg of amino acid flow/kg of DM intake (DMI) using the formula as reported by Adedokun et al., (2007a).

EAA flow (mg/kg of DMI) = AA in ileal digesta (mg/kg) × [diet chromium (mg/kg)/ileal digesta chro-mium (mg/kg)].

Standardization of apparent ileal AA digestibility was as described by Adedokun et al. (2007b). Data were analyzed using the GLM procedure of SAS Insti-tute (2006) as a completely randomized design. Ileal EAA losses within an ingredient were compared be-tween broilers and 30- and 50-wk-old laying hens. The performance of birds fed diets containing 20% CP from different MBM or SBM samples were also determined. Standardized ileal AA digestibility data for each feed ingredient sample were determined between broilers and 30-wk-old laying hens (MBM) or between broil-ers and 50-wk-old laying hens (SBM). Where necessary, mean separation was by Tukey and level of significance was set at P ≤ 0.05.

RESULTSThe analyzed CP (N × 6.25), Na, Ca, P, and CF

contents of the 7 MBM samples are shown in Table 2. The average values (%) for CP, Na, Ca, P, and CF were 51.4, 0.7, 9.4, 4.4, and 10.6, respectively. Meat and bone meal sample 6 had the lowest (0.5%) concentra-tion of Na, whereas MBM 2 had the highest concentra-tion of Na (1.1%). For Ca and P, MBM samples 4 and 5 had the highest and lowest concentrations, respectively. Meat and bone meal 1 had the lowest concentration of CF, whereas MBM 3 had the highest CF concentration (Table 2). The CP contents of the SBM 1, 2, and 3 were 47, 48, and 45%, respectively. Analyzed AA concentra-tions of the experimental diets are reported in Table 3. The analyzed CP contents of the diets are close to the

formulated values (20%). The DM values of the diet containing MBM 7 was lower (93%) than that of the other MBM samples (~97%). Ileal EAA values between the 21-d-old broilers and 30- or 50-wk-old laying hens were not different. Glutamic and aspartic acids had the highest EAA losses, whereas Met and His were the AA with the lowest EAA losses (Table 4). Source of MBM affected (P < 0.05) weight gain, feed intake, and feed efficiency of broiler chickens (Table 5). Birds fed diets containing MBM 3 and 7 had the highest (P < 0.05) 5-d weight gain (average of 168 g), with birds on diet containing MBM 6 having the lowest (P < 0.05) 5-d gain (104 g/bird). Birds on MBM 7 had the highest (P < 0.05) weight gain and feed efficiency. Broilers on MBM 6 had the lowest (P < 0.05) feed efficiency. Feed efficiency for broilers on the remaining 5 MBM samples (MBM 1, 2, 3, 4, and 5) were not different. The 3 SBM diets did not result in any significant effect in broiler performance (gain, feed intake, and feed efficiency; Ta-ble 5). Standardized ileal AA digestibility values for the 7 MBM samples are reported in Table 6. Laying hens (30-wk-old) fed diets containing MBM 1 and 6 had higher (P < 0.05) DM digestibility values com-pared with 21-d-old broilers. Broilers’ SIAAD values were higher (P < 0.05) for MBM 3, 4, 5, and 7 relative to that of laying hens. With the exception of Cys, no differences in SIAAD values for SBM 2 were observed. Broilers on SBM 1 and 3, however, had higher (P < 0.05) SIAAD values for Met, Thr, Val, Ala, Cys, Gly, and Ser (Table 7). Dry matter digestibility values for the 3 SBM samples were higher (P < 0.05) in broilers (Table 7).

DISCUSSIONThe importance of adequately determining SIAAD

values of different feed ingredients in poultry nutrition cannot be overemphasized, especially in the light of in-creased demand for corn and SBM. To be able to ef-fectively use SBM, MBM, and other by- or co-products in poultry diets, the need exists for enough data from which reasonable decisions about diet formulation can be based. Additionally, evaluation of SIAAD values of these feed ingredients in both broiler chickens and lay-ing hens would shed more light on differences, if any, in how these strains of poultry are able to use MBM and SBM from different sources. The 7 MBM samples used in this study were highly variable in Na, Ca, P, and CF concentration; however, these values fall within what was reported for 12, 14, and 21 MBM from different sources by Adedokun and Adeola (2005b), Parsons et al. (1997), and Olukosi and Adeola (2009), respectively. The only MBM from pork (MBM 6) had the lowest Na content (0.5%).

The performance of birds fed diets containing differ-ent MBM samples was different, whereas those fed diets containing SBM were not. Five day average weight gain was highest for birds fed diets containing MBM 3 and 7, with an average gain of 168 g/bird. The smallest gain

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(104 g) was recorded for birds on the diet containing pork MBM (MBM 6). This gain (168 g) is lower than the 317 g that was reported (Kim and Corzo, 2012) for the average of 2 male stains (average of strains A and B) fed a semipurified diet containing an animal by-product. Differences in performance of birds fed MBM from different sources have been reported by Parsons et al. (1997) when they fed 14 different types of MBM

to broiler chicks for 9 d. In addition to strain effects, other reasons that may have affected BW gain in birds fed the MBM diets might include MBM mineral and CP contents and the inclusion of dextrose in the ex-perimental diets used in the study of Kim and Corzo (2012). Although intake was lower (312 vs. 371 g) in their study (Kim and Corzo, 2012), the dextrose might have been better used than corn starch. Kong and Ade-

Table 4� Ileal endogenous amino acid flow in 21-d-old broilers and laying hens

Item, mg/kg of DMI Broiler Laying hen1 Laying hen2 SD3

CP4 10,493 9,852 12,470 2,719.5Essential amino acid Arg 389 364 416 106.1 His 154 148 171 38.7 Ile 343 329 360 82.4 Leu 567 538 589 142.0 Lys 345 294 342 113.7 Met 107 111 112 35.0 Phe 608 500 520 103.0 Thr 557 547 624 116.6 Val 456 436 492 101.1 Mean 392 363 403 Nonessential amino acid Ala 388 389 411 99.1 Asp 722 728 773 179.2 Cys 240 218 261 45.3 Glu 926 931 999 251.0 Gly 454 419 473 90.8 Pro 488 440 500 87.5 Ser 556 517 596 109.4 Mean 539 520 573 N5 6 5 6

1Laying hens were 30 wk of age and were used for ileal endogenous amino acid losses measure for standardization of the 7 meat and bone meal samples’ apparent ileal digestibility values.

2Laying hens were 50 wk of age and were used for ileal endogenous amino acid losses measure for standardization of soybean meal samples’ apparent ileal digestibility values.

3Ileal endogenous amino acid flow within amino acid between broilers and laying hens were not different (P > 0.05).

4CP = nitrogen × 6.25.5N = number of replicates consisting of 8 (broilers) or 6 (laying hens) per replicate. Number of replicates for the

30-wk-old laying hens was 5 because of lack of enough samples from the sixth replicate cage.

Table 5� Effects of meat and bone meal (MBM) and soybean meal (SBM) from different sources on performance of broiler chickens from 16 to 21 d of age1

Item2 BW gain, g Feed intake, g Gain:feed, g/g

MBM 1 157b 291ad 0.541b

2 144bc 256bc 0.564b

3 160ab 281ab 0.568b

4 156be 282ab 0.551b

5 136ce 264be 0.515b

63 104d 234ce 0.444c

7 176a 255b 0.693a

SEM 4.59 6.99 0.014 P-value <0.0001 <0.0001 <0.0001SBM 1 260 374 0.695 2 257 361 0.711 3 267 378 0.708 SEM 8.49 7.91 0.020 P-value 0.69 0.32 0.73

a–eMeans within a column with different superscripts are significantly different (P ≤ 0.05).1Means represent 6 replicate pens of 8 birds per replicate. Means are on a per bird basis.2Each feed ingredient (meat and bone meal and soybean meal) was the only source of CP in each diet. Each

diet was formulated to contain 20% CP.3Porcine meat and bone meal.

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Tab

le 6

� C

ompa

riso

n of

app

aren

t ile

al D

M a

nd C

P d

iges

tibi

lity

and

stan

dard

ized

ile

al a

min

o ac

id d

iges

tibi

lity

betw

een

layi

ng h

ens

and

broi

ler

chic

kens

fed

7 d

iffer

ent

mea

t an

d bo

ne m

eal (M

BM

) sa

mpl

es1

Item

, %

MB

M 1

MB

M 2

MB

M 3

MB

M 4

MB

M 5

MB

M 6

2M

BM

7

Hen

Bro

iler

SEM

Hen

Bro

iler

SEM

Hen

Bro

iler

SEM

Hen

Bro

iler

SEM

Hen

Bro

iler

SEM

Hen

Bro

iler

SEM

Hen

Bro

iler

SEM

DM

d

iges

tibi

lity

71.5

a63

.9b

1.69

69.1

66.1

1.35

75.1

73.1

1.56

62.7

66.9

2.86

64.0

60.1

1.80

73.1

a65

.5b

1.04

73.5

72.1

1.15

CP

369

.067

.84.

2759

.967

.73.

2071

.0b

78.4

a1.

9847

.3b

65.8

a3.

0457

.9b

67.0

a2.

4466

.566

.71.

9370

.0b

78.2

a1.

57E

ssen

tial

am

ino

acid

Arg

75.2

75.8

3.75

69.2

75.4

2.43

75.2

b83

.1a

2.01

57.0

b73

.7a

2.66

65.7

b74

.9a

1.95

74.1

74.3

1.64

75.8

b83

.7a

1.98

His

68.5

66.4

3.63

61.2

70.5

3.92

71.7

b82

.8a

1.75

52.7

b66

.1a

3.17

65.5

b74

.9a

2.64

65.4

66.0

2.01

71.5

b79

.0a

1.35

Ile

72.7

70.5

3.80

61.9

68.5

3.86

73.5

b80

.7a

2.08

48.1

b64

.8a

3.19

64.9

b71

.1a

2.10

69.2

67.7

2.09

74.2

b80

.2a

1.65

Leu

74.7

73.5

3.36

65.4

71.9

3.24

75.1

b82

.3a

1.93

51.4

b67

.7a

2.92

66.5

b73

.3a

1.87

70.5

70.0

1.90

75.7

b82

.4a

1.55

Lys

70.7

70.4

4.06

61.5

70.3

3.84

73.3

b81

.4a

1.82

47.9

b65

.8a

2.97

64.7

b73

.3a

1.77

71.7

75.0

2.20

75.5

b82

.9a

1.52

Met

72.8

71.8

3.61

60.5

69.3

4.34

75.9

b82

.3a

1.83

47.6

b65

.0a

3.12

68.1

b75

.3a

1.78

74.8

75.4

1.92

77.5

b83

.1a

1.35

Met

+ C

ys65

.359

.64.

2452

.954

.33.

6464

.370

.22.

8338

.6b

56.0

a4.

1358

.762

.12.

8253

.847

.72.

7462

.566

.12.

15 P

he78

.778

.03.

2767

.776

.23.

4177

.5b

85.8

a1.

9753

.8b

71.0

a3.

0769

.5b

75.6

a1.

5878

.378

.51.

7281

.5b

88.6

a1.

53 T

hr68

.366

.34.

0157

.964

.83.

5370

.0b

77.9

a2.

4542

.2b

62.1

a3.

7758

.766

.62.

5560

.359

.62.

5467

.3b

74.8

a1.

68 V

al72

.771

.73.

6363

.270

.63.

3573

.4b

80.9

a2.

0450

.0b

67.0

a2.

9964

.6b

71.6

a1.

9366

.566

.32.

0673

.8b

81.2

a1.

60 M

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425STANDARDIZED AMINO ACID DIGESTIBILITY

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ola (2013) reported that apparent ileal DM digestibility of different NFD increased with increasing proportion of dextrose in the diet. This, according to Kong and Adeola (2013), could be attributed in part to the differ-ence in the chemical structure of corn (polysaccharide) and dextrose (simple monosaccharide). In the present study, average (5 d) weight gained was not different between the 3 SBM samples in 21-d-old broilers with a mean of 261 g. The average BW gain in this study (~263 g) was lower than the 398 g (66% of 398 g) re-ported (Kim and Corzo, 2012) for the average of 2 male stains.

Ileal EAA losses in 21-d-old broilers and 30- and 50-wk-old laying hens were not different in this study. Although no significant difference was observed, it is important to note that for all the AA, ileal EAA losses in 50-wk-old laying hens were numerically higher than for 30-wk-old laying hens, whereas values for broilers were in between. In line with previous reports (Adedo-kun et al., 2007a; Golian et al., 2008), Met was the AA with the least flow, whereas Glu and Asp were the AA with the largest endogenous flow. Ileal EAA losses from broilers and laying hens in this study are higher than those reported by Adedokun et al. (2007a; 2009b). The reason for this could be partly attributed to the likely huge difference in dietary electrolyte balance (e.g., so-dium level ranged from 0.5 to 1.1%) and the ratio of corn starch and dextrose between the 2 NFD used as reported by Kong and Adeola (2013) and as explained in the review paper by Adedokun et al. (2011).

Standardized ileal AA digestibility values for the 2 MBM with the most similar minerals and CF composi-tion (MBM 3 and 4) was higher in broilers than in lay-ing hens. Despite these similarities, however, the varia-tion in SIAAD values between the 2 strains of poultry within each MBM sample was high. For example, the difference in SIAAD for CP, Lys, and Met between broilers and laying hens were 7.9, 8.1, and 6.4 percent-age units for MBM 3 and 18.5, 17.9, 17.4 percentage units for MBM 4, respectively. This observation strong-ly suggests that the quality of the AA in MBM 4 may have been seriously compromised during processing. Parsons et al. (1997) reported significant differences between conventional and cecectomized cockerels for all the 14 MBM evaluated with the conventional cocker-els having higher SIAAD values. This observation was similar to what we observed in this study, with 21-d-old broiler chickens having higher SIAAD values versus laying hens in 4 of the 7 MBM samples evaluated. Ad-ditionally, in the study by Kim et al. (2011), SIAAD of 2 MBM samples in precision-fed cecectomized roosters and broilers were different, with 1 each of the 2 strains of chicken having higher values for 1 MBM. In addition to method, strain effects might have contributed to the differences Kim et al. (2011) observed. Unlike MBM samples, SIAAD values for SBM were higher, with little difference in digestibility between laying hens and broil-ers. Broilers had higher SIAAD values for SBM 1 and 3 for Met, Ala, Cys, Gly, Ser, whereas the same was the case for Cys in SBM 2. Values reported for SBM

Table 7� Comparison of apparent ileal DM and CP digestibility and standardized ileal amino acid digestibility between laying hens and broiler chickens fed 3 different soybean meal samples1

Item, %

SBM 1 SBM 2 SBM 3

Laying hen Broiler SEM

Laying hen Broiler SEM

Laying hen Broiler SEM

DM 73.4b 80.7a 1.35 74.6b 80.3a 1.12 77.5b 81.5a 1.04CP2 86.5 89.0 1.31 87.0 88.3 1.16 87.8 90.2 1.02Essential amino acid Arg 92.3 92.8 0.74 92.6 91.5 0.84 92.6 93.2 0.65 His 88.9 91.0 0.95 89.1 89.5 1.07 89.2 91.1 0.76 Ile 86.6 89.6 1.12 86.7 87.8 1.16 87.4 89.9 0.90 Leu 86.8 89.8 1.08 87.4 88.2 1.11 87.6 89.9 0.86 Lys 88.7 90.7 1.04 89.0 88.9 1.10 88.1 90.8 0.95 Met 87.7b 92.3a 1.19 88.6 90.7 1.17 87.0b 92.5a 1.22 Met + Cys 81.6b 88.6a 1.55 82.6b 87.6a 1.34 82.9b 89.9a 1.30 Phe 90.1 92.7 0.95 90.4 91.1 1.04 90.9 92.8a 0.72 Thr 81.5b 87.4a 1.63 83.2 86.4 1.44 82.8b 87.7a 1.44 Val 85.8b 89.6a 1.21 86.1 87.8 1.20 86.4b 89.8a 1.02 Mean 87.0 90.5 87.6 89.0 87.5 90.8 Nonessential amino acid Ala 85.4b 89.3a 1.26 86.5 88.0 1.15 86.3b 89.8a 1.05 Asp 85.4 88.2 1.09 85.0 86.2 1.20 86.8 88.50 0.87 Cys 76.2b 85.4a 1.88 77.0b 84.5a 1.59 78.7b 87.2a 1.47 Glu 90.5 91.8 0.82 90.3 90.3 0.91 91.3 92.07 0.67 Gly 83.9b 87.9a 1.27 84.8 86.6 1.18 85.1b 88.5a 1.09 Pro 86.3 89.0 1.09 87.2 87.5 1.08 88.0 89.7 0.97 Ser 84.9b 89.5a 1.23 86.5 88.6 1.13 86.3b 89.6a 1.04 Mean 84.5 88.7 85.3 87.4 86.1 89.3

a,bMeans within ingredient with different superscripts are significantly different (P ≤ 0.05).1Means represent 6 replicates per strain (laying hens or broilers) with 6 (50-wk-old laying hens) or 8 birds (broilers) per replicate. Standardization

was by the N-free diet method.2CP = nitrogen × 6.25.

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(broilers) in this study is similar to what was reported by Szczurek (2009), with mean digestibility values for essential AA being slightly higher (90.1 vs. 87.3%).

These results emphasize the need for informed use of MBM as an alternative feed ingredient as a result of inconsistencies in the quality of the products. It is important to state that the original hypothesis that AA digestibility would be higher in laying hens compared with the broiler chicks turns out to be the opposite for 4 of the 7 MBM samples. In addition to the fact that each MBM sample is unique in its own right as a re-sult of sources of the raw materials for the MBM and processing techniques used in its production, 21-d-old broiler chickens were more efficient in AA digestion and absorption from MBM. The SIAAD of both the laying hens and broilers on the pork MBM sample (MBM 6) were low relative to the other 6 MBM samples. This again was confirmed by the low 5-d mean BW gain and low feed efficiency. This observation is interesting be-cause all the diets were formulated to contain 20% CP and the Na, Ca, P, and CF contents of this sample were within the range of the other MBM samples. Intake of birds on this MBM sample was not different from that of birds fed diets containing MBM 2 and 5. The only plausible reasons for this may be a result of poor AA quality of the processing conditions or of the quality of the fat in the MBM sample. Generally, values from the 7 MBM samples are similar to what was earlier reported for 4 MBM samples from different source fed to 21-d-old broiler chickens (Adedokun et. al., 2007b). Furthermore, values reported for conventional and ce-cectomized roosters by Parsons et al. (1997) were high-er than those obtained in the current study.

Although not measured in this study, the mean re-tention time or the digesta passage rate is another fac-tor that may have influenced the results obtained from the MBM samples used in this study. It is possible that the interaction between the different MBM components could have resulted in varying digesta speed across the gastrointestinal tract. The mean retention time of a particular feed could affect how much of the nutrients in a feed are digested and absorbed. McNab (1994) re-ported that the physical characteristics and the chemi-cal components of the diet (as a result of the ingre-dients composition of the diet) may affect the degree of nutrient utilization and this may, to some extent, depend on the digesta passage rate (Mateos and Sell, 1980; Rochell et al., 2012; Kong and Adeola, 2013).

In summary, SIAAD values from MBM are quite variable, and the capacity of 21-d-old broilers and 30-wk-old laying hens for AA digestion and absorption from MBM from different sources are quite variable, with broilers showing greater capacity for AA digest-ibility. This shows that a need exists to procure MBM from a consistent and reliable source so as to minimize variability in AA digestibility and, hence, birds’ perfor-mance. Data generated from this study could be used in formulating broiler and laying hens’ diets on a di-gestible AA acid basis. Formulation on a digestible AA

basis may reduce cost, reduce N and AA excretion, and increase flock uniformity and returns on investment; but it is important to realize that data from a broiler database for ingredient digestibility may not always be applicable to that of laying hens. Finally, as the role of difference in Ca and P requirements for 21-d-old broil-ers and adult laying hens were not factored into the design of this study, it may be necessary to further investigate the short time effect of dietary Ca and P on ileal AA digestibility of MBM from different sources.

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