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Ten mature female dogs (19.0 ± 0.4kg) were used in a replicated 5 × 5 Latin Square experiment to determine the feeding value of maize gluten meal (MGM) in a complete food fed to dogs. All foods contained 100g poultry meal/kg and graded levels of MGM (4–320g/kg dry matter) resulting in foods that were 100, 150, 200, 250 and 300g/kg crude protein (CP). Daily dry matter (DM) intake averaged 307 ± 7g/d. An increase in MGM resulted in an increase in faecal moisture from 516 to 575g/kg (linear; P < 0.001) and faecal DM output increased from 24.2 to 32.9g/d (linear; P < 0.001). The coefficient for apparent ileal digestibility (CIAD) of DM decreased from 0.89 to 0.83 (linear; P < 0.001) and the coefficient for apparent total tract digestibility (CTTAD) of DM decreased from 0.92 to 0.89 (linear; P < 0.001) as MGM increased. The coefficient for apparent large intestinal digestibility (CLIAD; 0.29) was not affected by treatment. Faecal excretion of CP increased from 5.6 to 8.1g/d (linear; P < 0.001) as MGM increased. Crude protein CIAD increased from 0.73 to 0.82 (linear; P < 0.002) with increasing MGM whereas, CP CLIAD was not affected by treatment (0.40). Crude protein CTTAD increased from 0.84 to 0.91 (linear; P < 0.001) as MGM increased. Methionine had the highest overall CIAD ranging from 0.92 to 0.93 and threonine had the lowest CIAD ranging from 0.65 to 0.75. These data indicate that MGM is a highly digestible protein source for canine foods with inclusions of 84 to 322g/kg.
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Animal Feed Science and Technology
116 (2004) 239–248
Evaluation of maize gluten meal as a protein
source in canine foods
Ryan M. Yamka, Susanna E. Kitts,
Alma D. True, David L. Harmon
Department of Animal Sciences, University of Kentucky, Lexington, KY, 40546-0215, USA
Received 15 July 2003; received in revised form 10 May 2004; accepted 26 June 2004
Abstract
Ten mature female dogs (19.0 ±0.4kg) were used in a replicated 5 ×5 Latin Square experiment to
determine the feeding value of maize gluten meal (MGM) in a complete food fed to dogs. All foods
contained100g poultry meal/kg and graded levels of MGM (4–320 g/kg dry matter) resulting in foods
that were 100, 150, 200, 250 and 300 g/kg crude protein (CP). Daily dry matter (DM) intake averaged
307 ±7 g/d. An increase in MGM resulted in an increase in faecal moisture from 516 to 575 g/kg (lin-
ear;P< 0.001)and faecalDM output increasedfrom 24.2to 32.9 g/d(linear; P< 0.001).The coefficient
for apparent ileal digestibility (CIAD) of DM decreased from 0.89 to 0.83 (linear; P< 0.001) and the
coefficient for apparent total tract digestibility (CTTAD) of DM decreased from 0.92 to 0.89 (linear; P
< 0.001) as MGM increased. The coefficient for apparent large intestinal digestibility (CLIAD; 0.29)
was not affected by treatment. Faecal excretion of CP increased from 5.6 to 8.1g/d (linear; P< 0.001)
asMGM increased.Crude protein CIADincreased from0.73 to 0.82(linear; P< 0.002)with increasing
MGMwhereas, CPCLIAD wasnot affectedbytreatment (0.40).Crudeprotein CTTAD increasedfrom
0.84 to 0.91 (linear; P< 0.001) as MGM increased. Methionine had the highest overall CIAD ranging
from 0.92 to 0.93 and threonine had the lowest CIAD ranging from 0.65 to 0.75. These data indicate
that MGM is a highly digestible protein source for canine foods with inclusions of 84 to 322 g/kg.
© 2004 Elsevier B.V. All rights reserved.
Keywords: Amino acids; Digestibility; Dogs; Maize gluten meal
Published as publication no. 03-07-010 of the Kentucky Agr. Exp. Station
Corresponding author. Tel.: +1 859 2577 516; fax: +1 859 2573 412.
E-mail address: dharmon@uky.edu (D.L. Harmon).
0377-8401/$ – see front matter © 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.anifeedsci.2004.06.007
240 R.M. Yamka et al. / Animal Feed Science and Technology 116 (2004) 239–248
1. Introduction
Commercial dry pet foods often contain cereals because of their low cost and as a starch
sourceforextrusionprocessing (Funaba et al., 2002). Maize gluten meal (MGM), a common
protein ingredient found in canine diets, is a by-product from the manufacturing of maize
syrup or starch. It is the dried residue after the removal of bran, germ and starch (Palika,
1996). Maize gluten meal could be an excellent source of protein for dogs, since nearly
600g/kg of the dry matter (DM) is crude protein (CP) and the sulphur amino acids are
highly digestible in other species (Sasse and Baker, 1973).
Littleresearch has beenpublisheddescribing the digestibilityofMGM by non-ruminants.
Maize gluten meal has often been added to broiler chick diets because it is a good source
of both methionine and cysteine and the amino acids are highly available (Sasse and Baker,
1973). Knabe et al. (1989) determined the apparent digestibility of nitrogen and AA in pro-
tein feedstuffs for growing pigs. Of the plant proteins analyzed (including soya bean meal),
MGM was the most digestible foodstuff of plant origin. Apparent nitrogen digestibility
measured at the ileum was 0.88 and 0.92 for the total digestive tract. When MGM was
fed to cats, Funaba et al. (2001) found that the apparent DM digestibility of MGM (0.74)
was comparable with fish meal (0.76). In a second study, Funaba et al. (2002) found that
MGM-based foods had apparent DM and CP digestibilities of 0.72 and 0.70, respectively.
The results of these studies indicate that MGM can be a valuable protein source in non-
ruminant foods; however, no research has been found reporting the value of MGM in canine
foods.
Knowledge of the digestible CP and AA of MGM instead of total dietary CP and AA
concentrations may lead to more accurate formulation of canine diets. The hypothesis
was that MGM can be an excellent source of high quality protein across a wide range of
inclusion levels. Therefore the objective of the present study was to determine the apparent
small intestinal digestibility of MGM-containing foods in response to increasing protein
from MGM.
2. Materials and methods
2.1. Dogs
Ten ileally cannulated (Walker et al., 1994) mature female mongrel dogs with body
weightsof 19.0 ±0.4 kg were used to evaluateprotein and AA disappearance atthe terminal
ileumand through thetotaltract. The dogswerelocated in theDivisionofLaboratoryAnimal
Research Facility at the University of Kentucky (Lexington, Kentucky) and were cared for
in accordance with Institutional Animal Care and Use Committee protocols. Dogs were
housed in an environmentally controlled room at 22C with a light:dark cycle of 14:10.
The kennels measure 1m ×1.5 m with vinyl-coated expanded metal flooring sitting 0.2m
above ground. Each kennel was cleaned twice daily following feeding. During this time
dogs were allowed 25min for exercise and socialization. Water was available ad libitum
throughout the experiment.
R.M. Yamka et al. / Animal Feed Science and Technology 116 (2004) 239–248 241
2.2. Feeding and treatments
The ingredient and chemical compositions of each food is presented in Tables 1 and 2.
Each food was extruded, kibbled and formulated in accordance with the Association of
American Feed Control Officials (2002) nutrient guide for dogs and balanced to meet
maintenance requirements (Tables 1 and 2). Differences between the five foods resulted
from varying proportions of MGM. The source of CP was MGM and foods were 100,
150, 200, 250 and 300g CP/kg. Chromic oxide was added to each food at 2g/kg DM to
serve as an indigestible marker to determine digestibility. Each day food was weighed and
divided into two equal portions and fed at 0700 and 1700 in stainless steel bowls. Each
dog was allowed 20min to consume the food. Bowls were removed after 20min and any
food remaining was weighed and recorded. Throughout the experiment, food samples were
collected daily and pooled into plastic collection bags for nutrient content analysis.
2.3. Sampling
The experiment was designed as a replicated 5 ×5 Latin Square. Each experimental
period was 14 d in length. During the first two days of the period, dogs were fed a 1:1
mixture of their current food and their respective next experimental food in order to avoid
meal refusal and gastric upset. Dogs were allowed 6 d for adaptation to each new food.
On the first day of faecal collection (d 7), all faeces were removed from the cages and
discarded prior to 0730. Faecal output was collected from this point on for the next5dat
each mealtime and placed into labeled plastic bags. Samples were frozen (15C), as they
were collected, and pooled by dog within each period.
Table 1
Ingredient composition of maize gluten meal diets fed to dogs to determine intestinal digestibility
Ingredient, g/kg of diet Treatment, g crude protein/kg
100 150 200 250 300
Maize starch 464.7 388.9 315.0 239.9 165.2
Maize gluten meal 4.483.8 163.2 241.8 322.0
Rice, brewers 250.0 250.0 250.0 250.0 250.0
Poultry meal 100.0 100.0 100.0 100.0 100.0
Grease, choice white 94.791.987.284.479.6
Spray-dried egg 25.025.025.025.025.0
Dicalcium phosphate 19.317.816.414.913.5
Soyabean oil 10.010.010.010.010.0
Palatability enhancer 10.010.010.010.010.0
KCl 9.79.69.49.39.2
Limestone 4.45.15.96.67.4
Vitamin-trace mineral – antioxidanta3.33.43.43.63.6
Salt 2.52.52.52.52.5
aFormulated to supply at least (g/kg) 0.6 Mg, 1.9 Na, 6.6 K, 7.9 Cl, (mg/kg) 189 Fe, 163 Zn, 12 Cu, 15 Mn,
0.3 Se, 1.5 I, (IU/g) 18.2 vitamin A, 1.0 vitamin D, 0.19 vitamin E, (mg/kg) 0.3 biotin, 1491 choline, 1.9 folic
acid, 62 niacin, 18 pantothenic acid, 8.6 pyridoxine, 8.0 riboflavin, 42 thiamin and 0.13 vitamin B12.
242 R.M. Yamka et al. / Animal Feed Science and Technology 116 (2004) 239–248
Table 2
Chemical composition of maize gluten meal foods (DM)
Item Treatment (g crude protein/kg)
100 150 200 250 300
Dry matter g/kg, DM basis 952.0 947.0 953.0 963.0 963.0
Organic matter 960.0 960.0 957.0 966.0 962.0
Crude protein 109.0 141.0 199.0 248.0 294.0
Crude fat 124.0 126.0 126.0 127.0 127.0
ME, MJ/kg 15.115.115.115.115.1
Crude fibre 22.022.023.024.024.0
Calcium 8.08.08.08.08.0
Phosphorous 6.06.06.06.06.0
Essential amino acids
Arginine 6.87.88.910.712.6
Histidine 2.12.73.85.16.0
Isoleucine 3.74.56.17.39.2
Leucine 7.713.522.531.039.3
Lysine 5.66.37.68.810.1
Methionine 3.94.55.15.66.5
Phenylalanine 4.16.39.712.816.3
Threonine 4.05.17.18.310.6
Tryptophan 1.71.82.02.22.4
Valine 4.05.27.28.811.0
Nonessential amino acids
Alanine 6.810.015.718.724.1
Aspartate 8.310.313.416.120.0
Cysteine 1.72.12.73.43.9
Glutamate 15.523.535.045.358.8
Glycine 7.88.610.311.712.9
Proline 6.19.615.419.224.6
Serine 5.07.010.112.816.3
Tyrosine 2.64.36.89.012.0
Sampling of digesta from the ileum lasted for 3 d, and started at the completion of the
faecal period. During ileal collection, Bite-not®collars were placed on the dogs after the
morning feeding and removed after the last collection. These collars allowed the dogs to
drink water normally and prevented the removal of their collection bags which are attached
to the cannulas during sampling times. Ileal digesta collection began at 0800 on d 12. Plastic
30mL-Whirl-Pak®collection bags (Nasco, Fort Atkinson, WI) were placed on the animal’s
cannula to collect the ileal digesta. On d 12 and 13 digesta were collected at hours 0800,
1000, 1200, 1400 and 1600. On d 14 samples were collected at hours 0900, 1100, 1300 and
1500. At each collection time samples were weighed, added to a pooled sample (by dog for
each period) and frozen (15C).
2.4. Analyses
After collection faecal and ileal samples were stored frozen (15C) until they were
lyophilized using a Dura-Dry®MP Freeze-Drier (FTS Systems®, Stone Ridge, NY). Dry
R.M. Yamka et al. / Animal Feed Science and Technology 116 (2004) 239–248 243
matter was determined as the difference in sample weight before and after lyophilization.
Faecal samples were then ground through a 0.5 mm screen in a Cyclotec 1093 Sample Mill
(Tecator, Hoganas, Sweden). Ileal samples were ground using a mortar and pestle. Feed
sampleswereground using a blender (Hamilton Beach/Proctor-Silex,Inc., Glen Allen, VA).
The dried and ground samples were then stored in labeled plastic bags at room temperature
until further analysis.
Ileal, faecal and feed samples were dried, ashed and digested, as described by Williams
etal. (1962). The solutions were allowed to settle and wereanalyzed the following day using
a ATI Unicam 99®atomic absorption spectrophotometer (Cambridge, UK) to determine
Cr concentrations in the samples. Protein content (N ×6.25) of the samples was obtained
using a LECO CNS2000 (St. Joseph, MI) nitrogen analyzer.
Samplesof food, ileal and control samples were prepared for amino acid analysis accord-
ing to methods 998.15 (sulphur and regular) and 994.12 (tryptophan) of the Association of
Official Analytical Chemists (1995).A10L aliquot of the resulting solution was deriva-
tized with 6-Aminoquinolyl-N-Hydroxysuccinimidyl carbamate and AA concentration was
determinedbyreversephase liquid chromatography usingMillipore WatersAccQTagSys-
tem, as described by Liu et al. (1995).
2.5. Calculations and statistics
Digestibility was calculated as described by Merchen (1988) using chromium as an
indigestible marker. Digesta flows were adjusted for the amount of marker recovered in the
faeces during the 5-d faecal collection. Digesta flows were calculated by dividing fecal Cr
excretion, g/d, by marker concentration in the digesta sample. The amount of AA supplied
exclusively by MGM was calculated using the amount of AA disappearing from the 100g
CP/kg food which was subtracted from the remaining foods to determine AA disappearance
of MGM supplied AA.
Data were analyzed as a replicated 5 ×5 Latin Square using the General Linear Models
and Regression procedures of SAS (1989). The experimental unit was the dog, the model
included dog, treatment, period (square) and dog (square), and the error was residual er-
ror mean square. Means were separated using polynomial contrasts for linear, quadratic
and cubic effects of MGM inclusion. Differences were considered significant when
P< 0.05.
3. Results
Alldogs remained healthy throughout theexperiment.There were no majordifferencesin
bodyweightduring the experiment (P= 0.361, Table3). Because intakes were adjusted each
period for maintenance of body weight, there were no differences in DM intake (P= 0.518).
Byincreasing the MGM in the foods faecal moisture increased (linear: P< 0.001)and faecal
DM output and ileal DM flow increased linearly (P< 0.001 and P< 0.001, respectively).
Coefficients for small intestinal (CIAD) and total tract (CTTAD) apparent digestibilities
decreased (linear: P< 0.001 and P< 0.001) as MGM increased. The coefficient for large
intestinal apparent digestibility (CLIAD) was not affected by treatment.
244 R.M. Yamka et al. / Animal Feed Science and Technology 116 (2004) 239–248
Table 3
Influence of protein source on dry matter (DM) digestibility in dogs fed increasing concentrations of maize gluten
meal
Item Treatment, g crude protein/kg Contrastsb
100 150 200 250 300 S.E.M.aLinear Quadratic
Body weight, kg 19.418.919.419.018.90.27 0.361 0.820
DMI, g/d 314.5 301.3 310.2 302.3 308.94.89 0.518 0.227
Faecal moisture, g/kg 516.0 534.0 556.0 565.0 575.09.57 0.001 0.403
Faeces, g DM/ d 24.224.929.829.032.91.21 0.001 0.867
Ileal Flow, g DM/ d 34.834.942.342.251.33.11 0.001 0.369
DM digestibility
Small intestine 0.89 0.88 0.86 0.86 0.83 0.097 0.001 0.426
Large intestinec0.29 0.29 0.28 0.28 0.32 0.024 0.533 0.305
Total tract 0.92 0.92 0.90 0.90 0.89 0.005 0.001 0.892
aStandard error of mean n= 10.
bProbability of greater Fvalue.
cPercentage of ileal flow.
Table 4 depicts CP (N ×6.25) digestibilities. As expected, CP intake increased (P<
0.001) with increasing CP concentration. There was also a linear increase (P< 0.001) in CP
faecal excretion and ileal flow of CP (P< 0.002). Crude protein CIAD linearly increased
(P< 0.002) with increasing MGM. Crude protein CLIAD was not affected by treatment.
Crude protein CTTAD increased linearly (P< 0.001) as MGM increased.
AminoacidCIADin cannulated dogs are shown in Table5. Arginine, lysine, methionine,
tryptophan, cysteine and glycine CIAD were not affected by increased MGM. All other
amino acid CIAD increased linearly with increasing MGM. Methionine had the highest
overall CIAD ranging from 0.92 to 0.93. Threonine had the lowest overall CIAD ranging
from 0.65 to 0.75.
Table 4
Influence of protein source on crude protein (CP) digestibility in dogs fed increasing concentrations of maize
gluten meal
Item Treatment, g crude protein/kg Contrastsb
100 150 200 250 300 S.E.M.aLinear Quadratic
CP intake, g/d 33.842.561.975.091.31.13 0.001 0.047
Faeces, g CP/d 5.66.97.57.58.10.48 0.001 0.289
Ileal flow, g CP/d 9.410.613.113.116.91.50 0.002 0.695
CP digestibility
Small intestine 0.73 0.75 0.79 0.82 0.82 0.023 0.002 0.525
Large intestinec0.40 0.38 0.39 0.41 0.45 0.031 0.193 0.275
Total tract 0.84 0.85 0.88 0.90 0.91 0.096 0.001 0.895
aStandard error of mean n= 10.
bProbability of greater Fvalue.
cPercentage of ileal flow.
R.M. Yamka et al. / Animal Feed Science and Technology 116 (2004) 239–248 245
Table 5
Ileal digestibility coefficients of amino acids in cannulated dogs
Item Treatment (g/kg crude protein) Contrastb
100 150 200 250 300 S.E.M.aLinear Quadratic
Essential amino acids
Arginine 0.86 0.85 0.85 0.88 0.86 0.014 0.513 0.684
Histidine 0.75 0.77 0.81 0.84 0.80 0.022 0.021 0.238
Isoleucine 0.79 0.79 0.81 0.83 0.83 0.015 0.014 0.965
Leucine 0.80 0.86 0.89 0.91 0.91 0.012 0.001 0.013
Lysine 0.77 0.77 0.78 0.80 0.76 0.025 0.710 0.515
Methionine 0.97 0.93 0.92 0.93 0.91 0.010 0.187 0.526
Phenylalanine 0.79 0.83 0.86 0.89 0.88 0.015 0.001 0.093
Threonine 0.65 0.66 0.72 0.75 0.74 0.030 0.009 0.510
Tryptophan 0.84 0.81 0.80 0.83 0.77 0.030 0.221 0.848
Valine 0.72 0.74 0.78 0.82 0.80 0.024 0.008 0.374
Nonessential amino acids
Alanine 0.81 0.84 0.88 0.89 0.89 0.013 0.001 0.100
Aspartate 0.68 0.69 0.73 0.76 0.75 0.024 0.006 0.707
Cysteine 0.67 0.70 0.70 0.75 0.72 0.030 0.099 0.468
Glutamate 0.81 0.84 0.87 0.89 0.89 0.012 0.001 0.110
Glycine 0.79 0.76 0.79 0.81 0.78 0.024 0.687 0.805
Proline 0.76 0.81 0.86 0.87 0.87 0.015 0.001 0.040
Serine 0.66 0.70 0.77 0.80 0.80 0.025 0.001 0.249
Tyrosine 0.72 0.79 0.83 0.86 0.86 0.020 0.001 0.050
aStandard error of mean, n= 10.
bProbability of greater Fvalue.
Amino acid CIAD exclusively for MGM are shown in Table 6. This was accomplished
by subtracting the amount of AA supplied in the 100g CP/kg diet since the increases in
CP were all supplied by MGM. Leucine had the highest CIAD (0.98). Tryptophan had the
lowest CIAD (0.60).
4. Discussion
The purpose of this study was to determine the CIAD of protein and AA in canine
foods containing increasing concentrations of MGM as a supplemental protein source. To
our knowledge, no previous research has been conducted to determine AA digestibility
for foods containing graded levels of MGM in dogs. This study showed that MGM is an
excellent source of digestible AA in dogs.
Findings are similar to those found when the digestibility of MGM as a protein source
was determined in pigs (Knabe et al., 1989). In general, Knabe et al. (1989) found that
MGM was highly digestible in pigs, and the protein quality was high. Nitrogen values for
CIAD and CTTAD were 0.88 and 0.92, respectively. However, apparent DM digestibility
was not determined so effects of soluble fibres and other dietary components on CIAD and
CLIAD for DM could not be compared.
246 R.M. Yamka et al. / Animal Feed Science and Technology 116 (2004) 239–248
Table 6
Ileal digestibility coefficients of amino acids supplied by maize gluten meal in cannulated dogsa
Item Maize gluten meal (g/kg)
84 163 242 322 Mean S.E.M.b
Essential amino acids
Arginine 0.86 0.83 0.92 0.87 0.87 0.025
Histidine 0.91 0.88 0.92 0.86 0.89 0.022
Isoleucine 0.94 0.86 0.91 0.82 0.88 0.043
Leucine 0.98 0.98 0.98 0.98 0.98 0.004
Lysine 0.85 0.80 0.87 0.77 0.82 0.038
Methionine 0.89 0.89 0.96 0.90 0.91 0.025
Phenylalanine 0.90 0.84 0.88 0.84 0.87 0.027
Threonine 0.83 0.84 0.88 0.81 0.84 0.020
Tryptophan 0.34 0.57 0.87 0.63 0.60 0.148
Valine 0.94 0.88 0.92 0.88 0.90 0.025
Non-essential amino acids
Alanine 0.97 0.93 0.95 0.93 0.94 0.013
Aspartate 0.85 0.84 0.87 0.82 0.85 0.015
Cysteine 0.92 0.77 0.84 0.76 0.82 0.056
Glutamate 0.96 0.92 0.94 0.92 0.94 0.014
Glycine 0.62 0.84 0.87 0.78 0.78 0.078
Proline 0.94 0.95 0.96 0.94 0.95 0.008
Serine 0.89 0.88 0.92 0.87 0.89 0.014
Tyrosine 0.99 0.96 0.95 0.96 0.96 0.012
aTheamount ofAA supplied exclusively by MGM wasdetermined foreach food. The amount ofAA disappear-
ance from the 100 g CP/kg food was subtracted from the remaining foods in order to determine AA disappearance
of MGM supplied AA.
bStandard error of mean, n= 10.
When MGM was fed to dogs in the present study, CP CIAD ranged from 0.73 to 0.82
and CTTAD ranged from 0.84 to 0.91 (Table 4). The fact that CIAD increased as MGM
concentration increased suggests that MGM is highly digestible in the dog. However, when
CIAD for DM was determined we noticed a slight decrease with increasing inclusions of
MGM. It is unclear why this decrease in digestibility occurred. Since MGM is 600 g CP/kg
it contains a degree of non-protein components. The presence of indigestible sugars and
pectins has been shown to depress digestibility of other plant protein sources; however, no
differenceswere noticed in CLIAD, which would beindicativeof their presence with higher
MGM inclusions. Digestibility of CP could have been lower at the lowest inclusion levels
because endogenous CP excretion would have represented a larger proportion of excreted
CP at these lower inclusion levels. That is a disadvantage of treatments changing in CP con-
tent; however, to balance CP would have required addition of multiple ingredients making
the evaluation of MGM more difficult. The comparatively small changes in faecal CP excre-
tion, (approximately 2g/d) compared with the larger changes in CP intake (approximately
60 g/d) indicate that changes in endogenous secretion with increasing CP intake were prob-
ably small and supports this experimental approach for the evaluation of a single protein
ingredient.
R.M. Yamka et al. / Animal Feed Science and Technology 116 (2004) 239–248 247
The present study indicates that MGM supplemented to poultry meal at an inclusion of
4.4 g/kg (100g CP/kg food) of the food can supply adequate amounts of digestible methio-
nine, tryptophan, leucine, histidine, arginine, and lysine when compared to NRC (1985)
requirements for adult canine maintenance. However, inadequate amounts of digestible
isoleucine, threonine, phenylalanine and valine were supplied by the 100 g CP/kg food. The
maintenance requirements for isoleucine, phenylalanine, threonine and valine were not met
until MGM was supplemented as 83.8g/kg (150 g CP/kg) of the food.
If the difference in AA digestibility between the 100g MGM/kg food and the remaining
foodsare determined, theapparentAA digestibility ofMGM(Table6) canbecalculated. The
AA CIAD of MGM in dogs ranged from 0.60 (tryptophan) to 0.98 (leucine). These findings
are generally in agreement with Knabe et al. (1989), when MGM was fed to pigs. Knabe
et al. (1989) determined that phenylalanine and leucine had the highest digestibilities (0.96
for both) of the essential AA studied. In the dog leucine CIAD was also highest; however,
phenylalanine was lower (0.87). Lysine CIAD were similar between the pig and dog (0.80
versus 0.82, respectively) whereas tryptophan tended to be lower in the dog (0.60 versus
0.72). The foods utilized in the present study did not have MGM as the only protein source.
They also contained brewer’s rice at dietary inclusions of 250 g brewer’s rice/kg in each
food. Brewer’s rice is also a source of protein and AA, is highly digestible and contains
75g CP/kg on a DM basis. Brewer’s rice contributed < 20 g of total protein/kg and thus
contributed from 0.067 to 0.20 of the total CP.
Althoughnopreviousresearch hasevaluatedMGM for dogs the digestibility of SBMand
other plant by-products have been studied extensively in dogs. Kendall and Holme (1982)
determined the digestibilities of SBM and various plant by-products; it was concluded
that soya bean products had a higher apparent digestibility when compared to other plant
by-products. However, MGM was not utilized in the experiment.
Zuo et al. (1996) compared the digestibilities of low oligosaccharide SBM and SBM to
poultry meal (PM) in ileal cannulated dogs. The CIAD and CTTAD for DM for all foods
ranged from 0.59 to 0.62 and 0.76 to 0.80, respectively. Crude protein CIAD and CTTAD
for all foods ranged from 0.68 to 0.78 and from 0.80 to 0.84, respectively. In the present
study, MGM CIAD and CLIAD for DM ranged from 0.83 to 0.89 and 0.89 to 0.92. Crude
protein CIAD and CLIAD ranged from 0.73 to 0.83 and 0.84 to 0.91, respectively. When
compared to the SBM used by Zuo et al. (1996), MGM has a higher overall digestibility.
The difference in digestibilities amongst the two protein sources could be the result of lower
fibre levels and lack of indigestible sugars and complexes that are commonly associated
with SBM (indigestible oligosaccharides, phytate, etc.). Approximately 200g/kg DM of
MGM is starch which has been shown to be highly digestible (>0.90) in dogs (Murray
et al., 1999). However, comparisons between studies may be difficult because of different
sources of maize starch and dogs utilized in each experiment.
Maize gluten meal is a comparable protein source to PM when comparing data from
the present study to a previous study investigating the nutritional value of PM as a protein
source in canine foods (Yamka et al., 2003). The average CIAD for DM (0.88) and CP
(0.78) of PM observed by Yamka et al. (2003) are similar to the average CIAD for DM
(0.87) and CP (0.78) of MGM.
In summary, the digestibility of MGM was investigated by adding increasing amounts
of MGM in the food. Maize gluten meal is highly digestible and the protein quality is high.
248 R.M. Yamka et al. / Animal Feed Science and Technology 116 (2004) 239–248
The CP and AA digestibility increased with increasing dietary MGM indicating MGM can
be an effective protein source at various percentages of the overall food. This information
can be utilized to more accurately formulate canine foods containing MGM.
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