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Evaluation of low-ash poultry meal as a protein source in canine foods

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Eight mature female dogs (18.0 +/- 0.2 kg) were used in a replicated 4 x 4 Latin square experiment to determine the feeding value of low-ash poultry meal (PM) in a complete food fed to dogs. All foods contained graded concentrations of PM (10.4 to 32.5% DM), resulting in foods that were 10, 15, 20, and 25% CP. Daily DMI averaged 284 +/- 14 g/d. An increase in PM resulted in an increase in fecal moisture from 44.7 to 55.1% (linear; P < 0.01), and fecal DM output increased from 24.8 to 31.6 g/d (linear; P < 0.05). Ileal DM flow increased from 27.1 to 40.7 g/d (linear; P < 0.01). Small intestinal DM digestibility decreased from 90.4 to 86.1% (linear; P < 0.01) and total-tract DM digestibility decreased from 91.2 to 89.4% (linear; P < 0.01) as PM increased. Large intestinal DM digestibility increased from 8.4 to 21.1% with increasing PM (linear; P < 0.05). Fecal excretion of CP increased from 5.6 to 10.0 g/d (linear; P < 0.01) and ileal flow of CP increased from 6.9 to 15.6 g/d (linear; P < 0.01) as PM increased. Small intestinal CP digestibility was unaffected with treatment (P > 0.05). Large intestinal CP digestibility increased from 21.6 to 37.1% (linear; P < 0.05) with increasing PM. Total-tract CP digestibility increased from 81.0 to 86.6% (linear; P < 0.01) as PM increased. Arginine had the highest overall digestibility ranging from 88.5 to 91.3%, whereas cysteine had the lowest digestibility, ranging from 67.1 to 71.4%. These data indicate that PM is a highly digestible protein source for canine foods with inclusions of 10.4 to 32.5% of DM.
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R. M. Yamka, U. Jamikorn, A. D. True and D. L. Harmon
Evaluation of low-ash poultry meal as a protein source in canine foods
2003, 81:2279-2284.J ANIM SCI
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Evaluation of low-ash poultry meal as a protein source in canine foods
1
R. M. Yamka, U. Jamikorn, A. D. True, and D. L. Harmon
2
Department of Animal Sciences, University of Kentucky, Lexington 40546
ABSTRACT: Eight mature female dogs (18.0 ± 0.2
kg) were used in a replicated 4 × 4 Latin square experi-
ment to determine the feeding value of low-ash poultry
meal (PM) in a complete food fed to dogs. All foods
contained graded concentrations of PM (10.4 to 32.5%
DM), resulting in foods that were 10, 15, 20, and 25%
CP. Daily DMI averaged 284 ± 14 g/d. An increase in
PM resulted in an increase in fecal moisture from 44.7
to 55.1% (linear; P < 0.01), and fecal DM output in-
creased from 24.8 to 31.6 g/d (linear; P < 0.05). Ileal
DM flow increased from 27.1 to 40.7 g/d (linear; P <
0.01). Small intestinal DM digestibility decreased from
90.4 to 86.1% (linear; P < 0.01) and total-tract DM di-
gestibility decreased from 91.2 to 89.4% (linear; P <
0.01) as PM increased. Large intestinal DM digestibility
Key Words: Amino Acids, Ash, Digestibility, Dogs
2003 American Society of Animal Science. All rights reserved. J. Anim. Sci. 2003. 81:2279–2284
Introduction
Poultry meal (PM) is of considerable value as a protein
source in canine foods. Information on the chemical com-
position and nutrient digestibility of poultry meal indi-
cates that it can be a variable product (Han and Parsons,
1990; Johnson et al., 1998). Two factors believed to affect
AA digestibility of animal meals are ash content and
processing temperature.
Results of research on apparent digestibility of AA
from various sources of PM have been inconsistent.
Johnson et al. (1998) found that the low-ash PM had a
slightly higher apparent digestibility of the essential AA
than the high-ash PM (68.0 vs. 66.9%). However, the
low-ash meat and bone meal was significantly lower in
apparent digestibility of AA than the high-ash meat and
bone meal (approximately 16 percentage units). From
this, Johnson et al. (1998) determined that any reduction
in protein quality with increased ash content was the
result of decreased concentrations of AA per unit of pro-
1
Published as publication No. 02-07-158 of the Kentucky Agric.
Exp. Stn.
2
Correspondence—phone: 859-257-7515; fax: 859-257-3412; E-
mail: dharmon@uky.edu.
Received August 29, 2002.
Accepted June 4, 2003.
2279
increased from 8.4 to 21.1% with increasing PM (linear;
P < 0.05). Fecal excretion of CP increased from 5.6 to
10.0 g/d (linear; P < 0.01) and ileal flow of CP increased
from 6.9 to 15.6 g/d (linear; P < 0.01) as PM increased.
Small intestinal CP digestibility was unaffected with
treatment (P > 0.05). Large intestinal CP digestibility
increased from 21.6 to 37.1% (linear; P < 0.05) with
increasing PM. Total-tract CP digestibility increased
from 81.0 to 86.6% (linear; P < 0.01) as PM increased.
Arginine had the highest overall digestibility ranging
from 88.5 to 91.3%, whereas cysteine had the lowest
digestibility, ranging from 67.1 to 71.4%. These data
indicate that PM is a highly digestible protein source
for canine foods with inclusions of 10.4 to 32.5% of DM.
tein, and not decreased digestibility. The results of other
poultry byproduct studies have varied. Zuo et al. (1996)
determined that apparent digestibility of essential AA
of poultry byproduct meal averaged 69.7% in dogs. Mur-
ray et al. (1997) found a higher apparent digestibility of
essential AA (81.0%) of poultry byproduct meal, indicat-
ing that the protein source was of higher quality when
compared with Zuo et al. (1996). Other studies have
shown digestibilities ranging from 77 to 89% of CP in
poultry based foods (Zuo et al., 1996; Murray et al., 1997).
Studies investigating the digestibility of PM in dogs have
ranged in concentrations of 7 to 32% of the total food
(Zuo et al., 1996; Murray et al., 1997; Johnson et al.,
1998). However, no individual study has investigated the
effect increasing PM has on apparent small intestinal
digestibility of AA in the dog. Therefore, the objective of
the present study was to determine the apparent small
intestinal digestibility of AA in response to increasing
protein from low-ash PM.
Materials and Methods
Dogs
Eight ileally cannulated (Walker et al., 1994) mature
female mongrel dogs with BW of 18.2 ± 0.2 kg were
used to evaluate protein and AA disappearance at the
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Yamka et al.2280
Table 1. Crude protein and amino acid composition
of protein sources used to formulate
the low-ash poultry meal foods
a
Item, Low-ash Brewer’s
% of DM poultry meal rice
Crude protein 69.3 8.3
Arginine 4.37 0.69
Cysteine 1.32 0.19
Glycine 6.53 0.38
Histidine 1.71 0.28
Isoleucine 2.34 0.31
Leucine 4.77 0.70
Lysine 3.11 0.32
Methionine 1.13 0.24
Phenylalanine 2.69 0.42
Threonine 3.02 0.31
Tryptophan 0.52 0.10
Tyrosine 1.84 0.13
Valine 3.16 0.48
Aspartate 5.58 0.78
Serine 4.42 0.43
Glutamate 8.60 1.46
Alanine 4.30 0.55
a
Analyzed before formulation of foods.
terminal ileum and through the total tract. The dogs
were located in the Division of Laboratory Animal Re-
search Facility at the University of Kentucky (Lexing-
ton) and were cared for in accordance with Institutional
Animal Care and Use Committee protocols. Dogs were
housed in an environmentally controlled room at 22°C
with a light:dark cycle of 14:10. The kennels measured
1 × 1.5 m, with a slotted floor sitting 0.2 m above ground.
Each kennel was cleaned twice daily, following feeding
and allowing for 25 min of exercise and socialization with
other dogs and people. Water was available ad libitum
throughout the experiment.
Table 2. Ingredient composition of low-ash poultry meal foods
Crude protein in food, %
Ingredient, % 10 15 20 25
Corn starch
a
46.6 40.8 35.1 29.5
Low-ash poultry meal 10.4 17.8 25.0 32.5
Rice, brewers 25.0 25.0 25.0 25.0
Grease, choice white 9.5 8.8 8.0 7.0
Cellulose
b
2.5 2.5 2.5 2.5
Dicalcium phosphate 1.9 1.3 0.7
Calcium carbonate 0.4 0.3 0.2
Soybean oil 1.0 1.0 1.0 1.0
Palatability enhancer 1.0 1.0 1.0 1.0
Vitamin-trace mineral
c
1.7 1.5 1.5 1.5
a
Buffalo corn starch from Corn Products International, Westchester, IL.
b
Cellulose from J. Rettenmaier USA LP, Schoolcraft, MI.
c
Formulated to supply (at least) the following (g/kg of food): 0.6 Mg, 1.8 Na, 7.0 K, 7.6 Cl, (mg/kg of food)
211 Fe, 163 Zn, 13 Cu, 13 Mn, 0.4 Se, 1.5 I, (IU/g of food) 18.2 vitamin A, 1.0 vitamin D, 0.18 vitamin E,
(mg/kg of food) 0.3 biotin, 1,484 choline, 1.9 folic acid, 62 niacin, 18 pantothenic acid, 8.6 pyridoxine, 8.0
riboflavin, 41 thiamin, and 0.13 vitamin B
12
.
Feeding and Treatments
The ingredient and chemical compositions of each pro-
tein source and food are presented in Tables 1, 2, and
3. Each food was formulated, extruded, and kibbled in
accordance with the AAFCO (2000) nutrient guide for
dogs and balanced to meet maintenance requirements
(Tables 2 and 3); however, the 10 and 15% CP foods were
below the AAFCO minimum requirement of 18% CP.
Differences between the four foods were based on vary-
ing proportions of PM found in the dry food. The source
of CP was PM, and foods were 10, 15, 20, and 25% CP.
Chromic oxide was added to each food at 0.2% DM to
serve as an indigestible marker to determine digestibil-
ity. 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 20 min to consume
the food. Bowls were removed after 20 min, and orts
were weighed and recorded. Throughout the experiment,
food samples were collected daily and pooled into plastic
collection bags for nutrient content analysis.
Sampling
The experiment was designed as a replicated 4 × 4
Latin square. Each experimental period was 14 d in
length. During the first 2 d 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 problems. Dogs were allowed 6 d for adaptation to
each new food.
On the first day of fecal collection (d 7), all feces were
removed from the cages and discarded before 0730. Fecal
output was collected from this point on for the next 5 d
at each mealtime and placed into labeled plastic bags.
Samples were frozen as they were collected and pooled
by dog within each period.
The ileal sampling period consisted of the 3 d following
fecal collection. During ileal collection, Bite-not collars
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Low-ash poultry meal in canine foods 2281
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 were attached
to the cannulas during sampling times. Ileal digesta
collection began at 0800 on d 12. Plastic, 28-g Whirl-Pak
collection bags (Nasco, Fort Atkinson, WI) were placed
on the animals’ cannulas to collect the ileal digesta. On
d 12 and 13, digesta were collected at 0800, 1000, 1200,
1400, and 1600. On d 14, samples were collected at 0900,
1100, 1300, and 1500. At each collection time, samples
were weighed, frozen, and added to a pooled sample.
Analyses
After collection, fecal and ileal samples were stored
frozen until they were lyophilized using a Dura-Dry MP
Freeze-Drier (FTS Systems, Stone Ridge, NY). Dry mat-
ter was determined as the difference in sample weight
before and after lyophilization. Fecal 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 samples
were ground using a conventional blender (Hamilton
Beach/Proctor Silex, Washington, NC). The dried and
Table 3. Chemical composition of low-ash poultry meal foods
Crude protein in food, %
Item 10 15 20 25
Dry matter, % 93.6 94.0 93.9 94.2
Dry matter basis, %
Organic matter 95.5 95.4 95.2 94.8
Crude protein 10.4 15.1 20.4 25.9
Crude fat
a
12.5 12.6 12.8 12.8
ME, kcal/kg
a
3600 3600 3600 3600
Crude fiber
a
2.2 2.3 2.4 2.5
Calcium
a
0.8 0.8 0.8 0.8
Phosphorus
a
0.6 0.6 0.6 0.6
Essential amino acids
Arginine 0.69 0.97 1.29 1.59
Histidine 0.23 0.31 0.41 0.50
Isoleucine 0.17 0.31 0.49 0.62
Leucine 0.69 0.99 1.36 1.68
Lysine 0.49 0.74 1.05 1.34
Methionine 0.18 0.25 0.34 0.41
Phenylalanine 0.37 0.54 0.74 0.91
Threonine 0.41 0.58 0.81 0.98
Tryptophan 0.17 0.19 0.22 0.24
Valine 0.38 0.56 0.75 0.92
Nonessential amino acids
Alanine 0.71 0.97 1.26 1.53
Aspartate 0.87 1.24 1.69 2.05
Cysteine 0.13 0.16 0.21 0.24
Glutamate 1.47 2.08 2.75 3.40
Glycine 0.83 1.23 1.68 2.08
Proline 0.63 0.93 1.27 1.54
Serine 0.48 0.69 0.93 1.15
Tyrosine 0.27 0.37 0.50 0.62
a
Values are calculated.
ground samples were then stored in labeled plastic bags
at room temperature until further analysis.
Ileal, fecal, and feed samples were dried, ashed, and
digested as described by Williams et al. (1962). The solu-
tions were allowed to settle and were analyzed the follow-
ing day using an ATI Unicam 99 atomic absorption spec-
trophotometer (Cambridge, U.K.) to determine Cr con-
centrations in the samples. Protein content (N × 6.25)
of the samples were obtained using a Leco CNS2000
(Leco Corp., St. Joseph, MI) N analyzer (AOAC, 1995).
Amino acid analyses of feed and ileal samples were
determined according to AOAC (1995). A 10-L aliquot
was derivatized with 6-aminoquinolyl-N-hydroxy-
succinimidyl carbamate and the AA concentration was
determined by reverse-phase liquid chromatography us-
ing Millipore Waters AccQ Tag System, as described by
Liu et al. (1995).
Calculations and Statistics
Nutrient 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 feces during the 5-d fecal col-
lection.
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Yamka et al.2282
Table 4. Dry matter digestibility in dogs fed increasing
concentrations of low-ash poultry meal
Crude protein in food, % Contrasts
b
Item 10 15 20 25 SEM
a
Linear Quadratic
Body weight, kg 17.8 18.0 18.2 18.1 0.2 NS NS
DMI, g/d 278.8 269.4 294.5 295.1 7.6 P < 0.05 NS
Fecal moisture, % 44.7 49.6 51.3 55.1 1.1 P < 0.01 NS
Feces, g of DM/d 24.8 25.2 28.6 31.6 2.1 P < 0.05 NS
Ileal flow, g of DM/d 27.1 27.9 35.6 40.7 3.1 P < 0.01 NS
DM digestibility
Small intestine, % 90.4 89.9 87.8 86.1 1.1 P < 0.01 NS
Large intestine, %
c
8.4 8.8 15.5 21.1 4.6 P < 0.05 NS
Total tract, % 91.2 90.8 90.3 89.4 0.6 NS NS
a
Standard error of mean, n = 8.
b
Probability of a greater F- value.
c
Percentage of ileal flow.
NS = nonsignificant, P > 0.05.
Data were analyzed as a replicated 4 × 4 Latin square
using the GLM and regression procedures of SAS (SAS
Inst., Inc., Cary, NC). The experimental unit was dog,
the model included square, treatment, period (square),
and dog (square), and the error was residual error mean
square. Means were separated using polynomial con-
trasts for linear, quadratic, and cubic effects of PM inclu-
sion. Differences were considered significant when P <
0.05.
Results
All dogs remained healthy throughout the experiment.
There were no differences in BW during the experiment
(P > 0.05, Table 4). No differences in BW were expected
since foods were adjusted to supply the proper amount
of energy required for maintenance of BW each period.
Despite these attempts at equalizing intake, a linear
increase in intake (P < 0.05) with increasing PM oc-
curred. Fecal moisture increased linearly (P < 0.01), as
did fecal DM output and ileal DM flow (P < 0.05 and P
Table 5. Crude protein digestibility in dogs fed increasing
concentration of low-ash poultry meal
Crude protein in food, % Contrasts
b
Item 10 15 20 25 SEM
a
Linear Quadratic
CP intake, g/d 28.8 40.6 60.0 73.8 0.2 P < 0.01 NS
Feces, g of CP/d 5.6 6.3 8.1 10.0 0.1 P < 0.01 NS
Ileal flow, g of CP/d 6.9 8.8 12.5 15.6 0.2 P < 0.01 NS
CP Digestibility
Small intestine, % 76.3 79.3 79.4 78.1 2.3 NS NS
Large intestine, %
c
21.6 24.1 27.4 37.0 4.0 P < 0.05 NS
Total tract, % 81.0 84.5 86.3 86.6 1.3 P < 0.01 NS
a
Standard error of mean, n = 8.
b
Probability of a greater F- value.
c
Percentage of ileal flow.
NS = non-significant, P >0.05.
< 0.01, respectively), in response to increasing the PM
in the foods. Small intestinal DM decreased as PM in-
creased (P < 0.01). Large intestinal DM digestibility in-
creased linearly (P < 0.05) as PM increased. Total-tract
DM digestibility was not affected (P > 0.05) by increas-
ing PM.
Table 5 depicts CP (N × 6.25) digestibilities. As ex-
pected, CP intake increased (P < 0.01) with increasing
CP. There was also a linear increase (P < 0.01) in fecal
CP excretion and ileal flow of CP (P < 0.01). Small intesti-
nal CP digestibility was not affected (P > 0.05) by in-
creased concentrations of PM, whereas large intestinal
CP digestibility increased linearly (P < 0.05). Total-tract
CP digestibility increased linearly (P < 0.01) as PM in-
creased.
Amino acid disappearance as a percentage of intake
is shown in Table 6. Digestibilities for all AA were not
affected by increased PM, with the exception of isoleu-
cine and tryptophan. Arginine had the highest digestibil-
ity, ranging from 88.5 to 91.3%. Cysteine had the lowest
overall digestibility, ranging from 67.1 to 71.4%.
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Low-ash poultry meal in canine foods 2283
Table 6. Disappearance of amino acids (percent of intake) in cannulated dogs fed
increasing concentrations of low-ash poultry meal
Crude protein in food, % Contrasts
b
Item 10 15 20 25 SEM
a
Linear Quadratic
Essential amino acids
Arginine 88.5 91.3 90.7 89.9 1.3 NS NS
Histidine 81.7 86.5 84.4 83.0 2.2 NS NS
Isoleucine 53.7 71.4 74.9 75.4 4.6 P < 0.01 NS
Leucine 78.3 83.5 83.5 82.6 2.3 NS NS
Lysine 77.1 83.0 83.0 82.0 2.6 NS NS
Methionine 86.3 89.0 90.3 89.0 1.6 NS NS
Phenylalanine 78.7 83.7 83.8 83.2 2.2 NS NS
Threonine 70.2 77.3 76.8 75.5 3.2 NS NS
Tryptophan 86.6 84.7 80.8 77.2 2.0 P < 0.01 NS
Valine 72.8 79.3 78.8 77.7 2.9 NS NS
Nonessential amino acids
Alanine 81.1 84.6 84.2 82.4 2.2 NS NS
Aspartate 68.9 76.0 72.8 69.4 4.0 NS NS
Cysteine 67.1 71.4 71.1 69.0 4.0 NS NS
Glutamate 80.2 84.5 83.3 81.8 2.3 NS NS
Glycine 80.3 85.6 83.8 81.7 2.4 NS NS
Proline 78.2 83.8 83.2 81.3 2.5 NS NS
Serine 70.1 77.6 76.2 75.3 3.2 NS NS
Tyrosine 75.6 80.0 80.0 78.7 2.7 NS NS
a
Standard error of mean, n = 8.
b
Probability of greater F-value.
NS = nonsignificant, P > 0.05.
Discussion
The purpose of this study was to determine the appar-
ent small intestinal digestibility of protein and AA in
response to increasing protein from low-ash PM. Total-
tract and small intestinal digestibility have been shown
to vary because of differences in processing conditions
and poultry byproduct sources (Muir et al., 1996; Zuo et
al., 1996; Murray et al., 1997; Johnson et al., 1998). The
results obtained in the present study are dissimilar to
the Johnson et al. (1998) study, which investigated low-
ash poultry byproduct meal as a protein source in canine
foods. Johnson et al. (1998) reported that DM small in-
testinal digestibility was 76% and CP small intestinal
digestibility was 68% for PM. Our values for small intes-
tinal and total-tract DM digestibility were approxi-
mately 7% higher (Table 4), indicating that the poultry
meal used in the present study may be of higher quality.
In another study, Zuo et al. (1996) fed an extruded
and kibbled food containing 32% poultry byproduct meal
to ileally cannulated dogs. The CP digestibilities were
approximately 10 percentage units lower (66% ileal di-
gestibility and 77% total tract) when compared with our
study. This lower digestibility suggests that the poultry
byproduct meal used in their study was lower quality
reinforcing the fact that poultry byproduct meal can be
highly variable.
The results from our canine AA digestibility study are
in agreement with Muir et al. (1996) and Murray et al.
(1997), who reported that poultry byproduct meal had
apparent digestibilities of AA ranging from 66 (aspar-
tate) to 89% (arginine) when poultry byproduct meals
were fed to dogs. Of the AA studied, arginine had the
highest small intestinal digestibility, whereas cysteine,
aspartate and isoleucine had the lowest. The small intes-
tinal digestibilities of AA observed by Muir et al. (1996),
Murray et al. (1997), and in the present study, are higher
than the digestibilities observed by Zuo et al. (1996) and
Johnson et al. (1998).
Variation in protein quality and AA availability
among major protein ingredients and the response to
varying levels of inclusion are of special concern to the
pet food industry. Because of differences in raw material
source and processing conditions, AA composition and
availability may be variable among animal meals. There-
fore, studies focusing on protein quality and AA avail-
ability of individual ingredients and different dietary
concentrations of these individual ingredients are
needed.
Increased processing time has been shown to decrease
digestibility and AA availability (Johnson et al. 1998).
Poultry byproduct normally contains only dry rendered
parts of the chicken, such as heads, feet, undeveloped
eggs, gizzards, and intestines, but not feathers, except
for the few that may be included from collection pro-
cesses. Renderers that provide poultry byproducts for the
pet food industry have different methods for determining
what will be utilized for byproducts. The differences in
sorting methods can lead to varying concentrations of
byproducts, resulting in a highly variable product (Mur-
ray et al., 1997). This variability can affect digestibility
and AA profiles, making it difficult to determine the
quality of the protein used to formulate canine foods.
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Yamka et al.2284
This study indicates that PM fed at an inclusion level
of 10.4% (10% CP) of the food can supply adequate
amounts of digestible leucine, histidine, arginine, threo-
nine, tryptophan, and lysine when compared to NRC
(1985) requirements for canine maintenance. However
inadequate amounts of digestible methionine, isoleucine,
phenylalanine, and valine were supplied by the 10% CP
food. The requirements for threonine and valine were
not met until PM was included as 17.8% (15% CP) of
the food. Isoleucine and phenylalanine requirements
were not met until PM was included as 25.0% (20% CP)
of the food. Therefore, foods containing less than 25.0%
PM as a supplemental protein source would not meet
the minimum AA requirements for maintenance in the
dog. To be able to effectively utilize PM in lower protein
foods (<20% CP), the food would need to include a phenyl-
alanine and isoleucine supplement or utilize another
protein source (plant protein source combined with ani-
mal protein source) to effectively supply all the essential
AA needed for canine maintenance. Brewer’s rice was
included as 25% of the DM in each food and contributed
from 8 to 20% of total protein. It is believed that the
contribution of brewer’s rice to total protein did not affect
digestibility in this study; thus, PM digestibility was
maintained across a wide range of inclusions.
These data show the value of ileal-cannulated dogs
to determine digestibility. Total-tract CP digestibility
increased with increasing PM; however, no differences
in small intestinal CP digestibility were observed. This
would result in large changes of AA utilization in the
large intestine. Further, microbial transformation or
production of AA in the large intestine can also lead to
erroneous estimates of digestion and absorption (Wil-
liams, 1995). Crude protein or AA present in the feces can
be of dietary, endogenous, or microbial origin, making it
impossible to differentiate AA origin in the feces.
The general assumption in the pet food industry is
that animal protein usually has a higher digestibility
and is of higher quality when compared to plant protein
sources. Proteins of plant origin usually have a lower
digestibility than animal proteins because plant ber
and carbohydrates lower digestion, due to a reduced deg-
radation rate of nutrients in the gut and increased bacte-
rial activity (Meyer, 1984; Neirinck et al., 1991; Murray
et al., 1997). The digestibility of PM in the present study
was investigated by adding increasing concentrations
of PM into the foods. A ranking of dietary treatments
according to apparent digestibility showed that ileal di-
gestibility of the 10% PM food for dogs tended to be
lower than that of 25% PM food. However, the impact
of endogenous protein and AA on apparent digestibility
would have been greatest for the 10% CP diet, and the
differences among digestibilities of all treatments were
small. These results show that PM is digested efficiently
at a wide range of concentrations in the dog.
Implications
For dogs, a high-quality protein source should contain
all the essential amino acids in proper amounts and be
readily bioavailable. The results of this study imply that
poultry meal in dietary inclusions of 10 to 32.5% of the
food can be an excellent source of protein for dogs; how-
ever, adequate amounts of digestible amino acids were
not supplied until poultry meal was incorporated as
32.5% (25% crude protein) of the dry matter. Comple-
mentary sources of protein may be needed to meet amino
acid requirements at lower protein intakes.
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Johnson, M. L., C. M. Parsons, G. C. Fahey, N. R. Merchen, and
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... When included in the diet in association with animal proteins, soy protein complements the essential amino acid profile and increases the nutritional quality of the food [9]. Additionally, because it is largely available, it contributes to reducing the production costs of commercial foods [11,12]. Soybean meal is a by-product derived from the grinding, heating and extraction of the lipid content of the grain [9]. ...
... In contrast to what was observed for soybean meal, most studies that investigated poultry offal meal did not describe statistical differences in the digestibility results [3,12,27,29,31,34]. Only one study [33], in which different inclusion levels were tested, showed opposite results, i.e., when the level of inclusion of the ingredient was increased, the ADC of DM decreased, whereas when its inclusion level was reduced, the ADC of DM increased. ...
... The ADC of CP was the variable that most varied in the results: 4 articles reported no statistical differences [10,13,31,34]; another 4 [3,25,27,29] showed reduced digestibility; and only one [9] described an increase in the coefficient. Results were divergent in only two articles [12,33], in which the authors compared increasing levels of inclusion and observed that higher levels resulted in increased digestibility of the ingredient, whereas lower levels induced a reduction in the ADC of CP. For the ADC of EE, no significant differences were described in most studies [9,10,13,29,31,33,34]. ...
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Soybean meal and poultry offal meal are protein ingredients commonly used in the formulation of commercial diets for dogs. However, there remains great variability in the data on the digestibility of each protein source. This systematic review study aimed to examine the intake, apparent nutrient digestibility coefficients and fecal output of protein sources (soybean meal and poultry offal meal) in adult dog food as reported in published studies. The article search was conducted in August 2018 in the PUBMED, SciELO, Science Direct and AGRIS indexing databases. The literature search was performed using "digestibility", "source protein" and "dog" as the main key terms combined with sub-terms to broaden the scope of the search. Criteria were defined for readability, exclusion and inclusion of articles. Results were organized in groups according to the search in the indexing databases, totaling 1,414 articles. After the works were selected following the inclusion criteria, 17 articles were evaluated in this review. According to most studies, plant-based ingredients have a less variable nutritional composition than animal-derived ingredients and poultry offal meal increases the digestibility coefficients of nutrients and energy and reduces fecal dry matter production. Factors inherent to raw-material origin, ingredient and food processing, as well as the high heterogeneity of the methodologies evaluated in the studies are directly related to the obtained results. To ensure a more accurate evaluation of the quality and of effects on the digestibility of protein sources, we recommended that articles include ingredient processing data and that the variables be evaluated under standardized study conditions.
... When included in the diet in association with animal proteins, soy protein complements the essential amino acid profile and increases the nutritional quality of the food [9]. Additionally, because it is largely available, it contributes to reducing the production costs of commercial foods [11,12]. Soybean meal is a by-product derived from the grinding, heating and extraction of the lipid content of the grain [9]. ...
... In contrast to what was observed for soybean meal, most studies that investigated poultry offal meal did not describe statistical differences in the digestibility results [3,12,27,29,31,34]. Only one study [33], in which different inclusion levels were tested, showed opposite results, i.e., when the level of inclusion of the ingredient was increased, the ADC of DM decreased, whereas when its inclusion level was reduced, the ADC of DM increased. ...
... The ADC of CP was the variable that most varied in the results: 4 articles reported no statistical differences [10,13,31,34]; another 4 [3,25,27,29] showed reduced digestibility; and only one [9] described an increase in the coefficient. Results were divergent in only two articles [12,33], in which the authors compared increasing levels of inclusion and observed that higher levels resulted in increased digestibility of the ingredient, whereas lower levels induced a reduction in the ADC of CP. For the ADC of EE, no significant differences were described in most studies [9,10,13,29,31,33,34]. ...
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O objetivo do presente trabalho foi estimar por metanálise os coeficientes de digestibilidade aparente da matéria seca (CDAMS) e proteína bruta (CDAPB) de ingredientes proteicos utilizados na dieta de cães adultos. Com base na compilação dos dados dos 12 artigos científicos escolhidos, houve diferença estatística (p<0,05) entre todos os grupos para o CDAMS, o qual superior para a farinha de vísceras de aves e inferior para a farinha de carne e ossos. Com relação ao CDA PB, não houve diferenças estatísticas (p>0,05) entre o farelo de soja e a farinha de vísceras de aves, e nesse caso o coeficiente apresentou os melhores resultados para a farinha de peixe e os inferiores para a farinha de carne e ossos (p<0,05).
... CM exhibited pro-oxidant behavior at 3 out of 5 tested concentrations and had an E max of only 5% at 0.2 mg/mL (see Figure 5 and Table 5). CM is commonly used in pet food preparations [52]. However, the outcomes of the current study indicate that CM inclusion offers little or no benefits relating to scavenging the ROS produced by activated neutrophils. ...
... CM exhibited pro-oxidant behavior at 3 out of 5 tested concentrations and had an Emax of only 5% at 0.2 mg/mL (see Figure 5 and Table 5). CM is commonly used in pet food preparations [52]. However, the outcomes of the current study indicate that CM inclusion offers little or no benefits relating to scavenging the ROS produced by activated neutrophils. ...
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European legislation permits the inclusion of insect proteins in pet and aquaculture diets. Black soldier fly larvae (BSF) are one of the most actively produced species due to their low environmental impact and nutritional characteristics. BSF protein derivatives (proteins and protein hydrolysates) contain a substantial amount of low molecular weight peptides that are known to possess antioxidant potential. In this study, the in vitro antioxidant potential of commercial BSF proteins and protein hydrolysates was investigated for (1) radical scavenging activity, (2) myeloperoxidase activity modulation, and (3) neutrophil response modulation. Chickenmeal and fishmeal are commonly used in pet food and aquaculture formulations. Hence, both were used as industrial benchmarks during this study. The results indicate that fishmeal and chickenmeal are ineffective at suppressing the oxidative damage caused by neutrophil response and myeloperoxidase activity. Fishmeal and chickenmeal even exhibit pro-oxidant behavior in some of the models used during this study. On the other hand, it was found that BSF protein derivatives could be effective in protecting against the cellular damage resulting from neutrophil and myeloperoxidase activities. The outcomes of this study indicate that BSF protein derivatives could be potentially included in pet food and aquaculture feed formulations as health-promoting ingredients.
... Some of these protein sources have been evaluated in an animal model (Johnson et al., 1998;Yamka et al., 2003Yamka et al., , 2004Dust et al., 2005). However, technology and material composition have changed over time. ...
... The proximate analysis and most amino acid composition data from samples agrees with prior published research and standard reference tables (Morita and Kiriyame, 1993;Fialho et al., 1995;Murray et al., 1997;Johnson et al., 1998;Hertrampf and Piedad-Pascual, 2000;Schmidt et al., 2003;Yamka et al., 2003;Keegan et al., 2004;Norberg et al., 2004;Dust et al., 2005;Ayadin et al., 2008;Guimarães et al., 2008;Hou et al., 2008;AAFCO, 2013;Lammert et al., 2014;Agarwal et al., 2015). There are a few exceptions. ...
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New protein ingredients are used to support pet food market growth and the development of new products while maintaining animal dietary needs. However, novel protein sources (e.g., spray-dried chicken, and (or) rice, pea, and potato protein concentrates) have limited data available regarding their protein quality. The objective of this study was to evaluate protein ingredients used in the pet food industry by laboratory analysis and a chick growth assay as a model. Following analysis for proximate and amino acid composition, chicks (six birds per pen with four pens per treatment) were fed experimental diets for 10 d. Diets contained 10% crude protein from each of the experimental protein sources (spray-dried egg-SDEG; spray-dried egg white-SDEW, spray-dried inedible whole egg-SDIE, chicken by-product meal-CBPM, chicken meal-CKML, low-temperature fluid bed air-dried chicken-LTCK, low-temperature and pressure fluid bed dried chicken-LTPC, spray-dried chicken-SDCK, whey protein concentrate-WPCT, corn gluten meal-CGML, corn protein concentrate-CPCT, potato protein isolate-PPIS, rice protein concentrate-RPCT, pea protein isolate-PEPI, soy protein isolate-SPIS, and soybean meal-SBML) along with an N-free diet (negative control). Chicks fed SDEG, SDIE, and LTPC had the highest protein efficiency ratio (PER; P < 0.0001; 5.18, 5.37, and 5.33, respectively), LTCK and SDCK were intermediate (4.54 and 4.79), and the CBPM and CKML were the lowest among the poultry proteins for EAA:NEAA, PER, and Lys availability. Among the vegetable proteins, PPIS and SBML had the highest PER values (3.60 and 3.48, P < 0.0001). In general, the chick PER method ranked the quality of animal protein sources higher than vegetable proteins, and these results were consistent with the EAA:NEAA ratio and Lys availability.
... In particular, dry pet foods prepared starting from only Chicken Fresh Meats (CFMs), a Mix of Chicken Fresh Meats and Chicken Meat Meals (CMix), and a formulation consisting of only Chicken Meat Meals (CMMs) were analyzed. Chicken-based dry pet food was chosen by virtue of its highquality protein source, additionally characterized by high digestibility [16,18]. A soluble protein content analysis, which represents a convenient digestibility index [10,13,17], was carried out using the Bradford assay [45]. ...
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Dry pet food, made of fresh meats and especially meat meals, represents one of the main types of complete food available on the market by virtue of its practicality and long shelf life. The kibble production process includes mixed thermal and mechanical treatments that help to improve the palatability and durability of the final product but may have undesirable effects on nutrient bioavailability and digestibility. An analysis of the protein and lipid content of different dry pet food formulations, together with an in vitro digestibility analysis, can reveal which formulation can provide a more nourishing diet for pets. In this study, a quantitative and qualitative analysis was performed on three different formulations of chicken-based dry pet food, consisting of fresh meats, meat meals, or a mix of these two. The soluble protein concentration was determined by the Bradford assay, while the crude protein content was assessed through the Kjeldahl method. Quadrupole time-of-flight liquid chromatography/mass spectrometry (Q-TOF LC/MS) was used to analyze the amino acid (AA) and lipid compositions. Finally, a gastric and small intestinal digestion simulation was used to determine the in vitro digestibility. The results show that dry pet food consisting only of chicken fresh meats has the highest content of soluble protein; it also contains more Essential AAs, Branched-Chain AAs, and Taurine, as well as a greater quantity of monounsaturated and polyunsaturated fatty acids. In addition, its in vitro digestibility was the highest, exceeding 90% of its dry weight, in agreement with the soluble protein content. These findings thus make the fresh-meat-based formulation a preferable choice as dry pet food.
... Apparent ileal and total tract digestibility values of CP were large for all diets. Much smaller apparent ileal digestibility of CP (28 to 34 percentage units) and smaller apparent total tract digestibility of CP (5 to 14 percentage units) are noted when ileally cannulated dogs or pigs are fed protein by-products [e.g., fish meal, poultry by-product meal, or meat meal diets (Jørgensen et al., 1984;Knabe et al., 1989;Zuo et al., 1996;Murray et al., 1997;Johnson et al., 1998;Bednar et al., 2000;Yamka et al., 2003)]. This undoubtedly is due to the protein quality of the test substrates. ...
... As regards the sum of SCFA and BCFA, despite of the higher protein content (Yamka et al., 2003) of the GF diet (39.24%, as-fed) than the CTR diet (24.40%, as-fed), dogs of the GF and CTR groups showed similar (P ¼ 0.913) content of the sum of organic acids in the faeces (Table 7). ...
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Two different diets characterized by the absence of cereals or by the presence of conventional cereals were evaluated on the nutrient digestibility and faecal characteristics and faecal fermentative end-product concentrations of 8 neutered adult Labrador retrievers housed at the Regional Centre Helen Keller (Messina, Italy) during the training work for the service guide for the blind. Dogs (age = 17 ± 1 months, initial body weight [BW] = 26.3 ± 1 kg, and body condition score [BCS] = 4.5 ± 0.11) were divided into 2 homogeneous groups for sex (half males and half females). Dogs in the grain free (GF) group were fed a commercial diet characterized by the absence of grain cereals, and dogs in the control (CTR) group were fed a super-premium pet food characterized by conventional grains as the carbohydrate source. The trial lasted 84 d, preceded by a 7-d of adaption period. Physical examination, digestibility, and faecal characteristics were studied. The statistical model included the effects of diet (GF vs. CTR), time (from d 0 to 84, end of the trial) and the interaction (diet × time). The high-protein, low-carbohydrate dry diet (GF) offered higher apparent nutrient digestibility of protein (+10%; P = 0.002) and fat (+7%; P
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The study aimed to measure variations in industrial process and nutritional variables of poultry by-product meal (PBM) in rendering plants from batch cookers. A total of 200 samples of low ash PBM with mineral matter (MM) content of 11% (LA, n = 104) or high ash with MM above 11% (HA, n = 96) were collected from 5 industrial processing plants. The highest coefficients of variation in chemical composition were for MM (LA - 19.70%; HA - 19.59%), ether extract (LA - 20.72%; HA - 14.86%), collagen (LA - 21.16%; HA - 30.00%) and water activity (LA - 24.54%; HA - 25.89%). However, the crude protein (LA - 5.07%; HA - 7.39%), dry matter (LA - 1.75%; HA - 2.90%) and organic matter digestibility (LA - 4.81%; HA - 6.78%) were lower. The variability of the data related to the process of PBM were: maximum process temperature (LA - 3.91%; HA - 3.56%), average process temperature (LA - 3.73%; HA - 4.71%) and processing time (LA - 27.37%; HA - 37.59%). This study evidenced that the corrective measures by limiting the amount of bones in the raw material, optimizing the pressing step for the poultry fat extraction, and also controlling the processing time of PBM may favor the production of more standardized PBM in terms of chemical composition and quality.
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Wild swarms of the long-horned grasshoppers Ruspolia differens (Serville) which are widely harvested for consumption and sale in Africa are seasonal and unsustainable, hence the need for innovative ways of artificially producing the insects. We investigated the development, survival, and reproduction of R. differens in the laboratory on diets mixed with host plants [Digitaria gayana Kunth, Cynodon dactylon (L.) and Megathyrsus maximus Jacq (Poales: Poaceae); Ageratum conyzoides L. (Asterales: Asteraceae)] identified from guts of their wild conspecifics with a view to developing a suitable diet for artificial mass rearing of the edible insect. A standard diet comprising ground black soldier fly, Hermetia illucens L. (Diptera: Startiomyidae) larvae, soybean flour, maize flour, vitamin premix, and ground bones was tested for rearing R. differens as a control against the same ingredients incorporated with individual powders of the different host plants. Whereas R. differens developed more slowly in the diet mixed with D. gayana than in the control diet; its development was faster in the diet mixed with C. dactylon. Mortalities of R. differens in host plant-based diets were 42.5-52.5%, far lower than in the control diet with 71% mortality. The insects raised on the diet mixed with M. maximus laid approximately twice more eggs compared to R. differens fecundities from the rest of the diets. However, inclusion of host plants in the diets had no detectable influence on R. differens adult weight and longevity. These findings support inclusion of specific host plants in artificial diets used for mass rearing of R. differens to enhance its survival, development, and fecundity.
Chapter
This chapter presents information on the different classes of animal discards that are available as well as factors that could influence their use in the diets of livestock. Meat and bone meal (MBM) is one of the most important animal discards that are important in swine and poultry feed both in terms of availability, cost, and nutrient and energy composition. MBM tankage, as well as meat meal and meat meal tankage are used to describe different types of animal discards that are composed primarily of meat and bone or meat alone. Miller and De Boer and Reese et al. provided information on the recommended level of inclusion of some animal discards in livestock feeds. The main challenge of using animal discards in livestock feed is that the nutrient and energy contents of these products vary widely between and within discards depending on the source, processing techniques, and geographical location.
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Several experiments were conducted to evaluate various methodologies for determining availability of amino acids (AA) and energy in alfalfa meal (AM), feather meal (FM), and poultry by-product meal (PBPM). Digestibility of AA was determined with 48-h precision-fed cockerel assays using conventional (CONV) and cecectomized (CEC) cockerels. Amino acid bioavailability was assessed with chick growth assays. True digestibility values of most AA were significantly lower for CEC than for CONV cockerels. In the chick growth assays, partitioning weight gains to reflect only growth attributable to supplemental crystalline AA or test feedstuff AA consumption often yielded higher bioavailability values than when total weight gains were used for FM and PBPM but lower ones for AM. The magnitude of differences between AA digestibility (cockerels) and AA bioavailability (chicks) values varied among feedstuffs; the largest differences were observed for FM. The TMEn values of AM and PBPM were lower for CEC birds than for CONV birds, whereas TMEn of FM was similar for both types of birds.
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A study of a new amino acid analysis method using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate as a precolumn derivatization reagent for the analysis of food and feed is described. All amino acids, including methionine sulfone and cysteic acid, were well separated on a liquid chromatographic system using the optimized chromatographic conditions. Salts in food and feed interfered very slightly with the derivatization yields of all amino acids. Several typical agricultural products and animal feeds, including 2 AOAC test samples, were analyzed with the method. The results agreed well with the data generated by using the classical postcolumn method with ion-exchange chromatography. The average relative standard deviations for corn and broiler starter feed were 0.74 and 0.70%, respectively. Good recoveries of all amino acids were demonstrated (average, 101%), even for a sample with a very complex matrix.
Article
Accurate assessment of amino acid requirements of livestock for maintenance and growth and accurate supply of these amino acids in feed is essential to optimise growth and production. During passage through the gut and during absorption, the composition of dietary supplied amino acids is modified compared with that absorbed into the portal circulation. Amino acids are utilised for endogenous secretion and protein synthesis in gut tissue and transamination occurs within the gut tissues. In pigs, each amino acid has its own characteristic of appearance in the portal vein which varies according to the amount of ingested protein. When small rather than larger amounts of amino acids are ingested, the absorbed mixture tends to be poorer in lysine, arginine, serine and proline and richer in histidine. Factors which influence the metabolism of gut tissue may alter the quantity and composition of amino acids absorbed. The gut micro-flora increases protein synthesis in gut tissue; in conventional compared with germ free chicks protein synthesis in gut and liver was increased by 36%. Raw kidney bean lectins produce hyperplasia in gut tissue, and the toxic effect is considerably increased by the presence of a normal gut microbial population. In-feed antibiotics appear to act at least at two levels, either via a nutrient sparing effect, with improvements in digestibility and/or enhanced absorption of amino acids plus a reduction in cell turn-over at the surface of the enterocyte. Hind-gut microbial fermentation influences amino acid digestibility. The lower the digestibility of the protein supplement the more microbial fermentation affects digestibility. Total tract digestibility is therefore not a good estimate of the amino acids absorbed in the small intestine. In intact compared with caecectomized cockerels there was little difference between faecal and ileal digestibility of amino acids for cereals, slight differences for oilseed meals, but significant differences for some animal meals. Lysine digestibility of meat and bone meal in intact and caecetomized birds was 0.88 and 0.82 respectively in meal without heat treatment and 0.58 and 0.45 respectively in heat treated meal. With diets for growing pigs in which meat and bone meal or cottonseed meal partially replaced soya bean meal, formulations based on ileal digestible amino acids produced better performance than those formulated on the basis of total amino acids. Ileal digestibility values are appropriate for estimation of amino acid digestibility of cereals as they account for losses in digestibility but in heat damaged meat meals differences exist between ileal digestibility and availability of lysine, methionine, threonine and tryptophan. Correlations between in vitro methods and in vivo ileal digestibility are quite close although in vitro values tend to be higher; inclusion of the association between amino acids and cell wall carbohydrates raises the variation explained between samples in ileal protein and amino acid digestibility to > 92%. Near-infrared reflectance spectrophotometry holds promise as a tool for predicting ileal digestibility. Use of ileal digestibility values in diet formulation increases the range of ingredients that can be employed, improves the accuracy of formulation and prediction of animal performance. Ileal digestibility measurements represent a good compromise between the requirement for a rapid, economical determination of the digestibility of amino acids in feed and the measurement of availability of amino acids for tissue synthesis.
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A rapid and accurate atomic absorption method for the determination of chromium in faeces samples from pasture experiments using chromic oxide ‘markers’ is described. Of the elements present after ashing and digesting the samples in a phosphoric acid—manganese sulphate—potassium bromate solution silicate, aluminium, calcium and magnesium were found to interfere in the determination. The effects of these interferences were overcome by the addition of calcium to the test solution and by the addition of silicate to the standards, which were prepared in ‘blank’ solutions. The sensitivities of a number of alternate chromium resonance lines relative to that of Cr 3578·7 Å. are given. These lines may be used to increase the concentration range of the analysis. The results of a comparison of the atomic absorption method with a chemical method are given.
Article
We studied the effects of dietary fibers with various fermentation characteristics on nutrient digestion at the distal ileum and in the total tract of dogs. The following high-protein (34%), high-fat (23%) diets were fed: 1) a control treatment (CON) with 0% supplemental fiber; 2) beet pulp (BP), 7.5%; 3) low-cellulose mixture (LCM), 2.5% cellulose + 5.0% pectin; 4) high-cellulose mixture (HCM), 5.0% cellulose + 2.5% pectin; or 5) Solka Floc (SF), 7.5% cellulose. Nutrient intakes by fiber-supplemented dogs were similar among treatment groups but greater (P < .05) than for dogs fed the control diet. Digestion of nutrients at the distal ileum was similar among groups except for fat: the dogs fed BP digested less fat than those fed the other sources of dietary fiber. Digestion of amino acids at the distal ileum was similar for all groups, except for lysine, which increased (P < .05) in digestibility as dietary cellulose concentration increased. Dogs consuming LCM had lower apparent ileal digestibility values for all nutrients, including most amino acids, than dogs consuming HCM or SF. Total tract digestion of DM and OM by dogs fed supplemental fiber was less (P < .05) than for dogs fed the control diet. The BP treatment was higher than other fiber treatments in total tract digestion of OM (P < .10) and total dietary fiber (P < .05). Total tract digestibilities of all nutrients exhibited either linear or quadratic responses to dietary cellulose concentrations. Apparent ileal and total tract nutrient digestion was influenced by the source of dietary fiber consumed.
Article
We investigated digestion responses to conventional and low oligosaccharide soybean meal (SBM) incorporation into diets for dogs. Five female dogs were fitted with T-type cannulas at the terminal ileum and fed five diets in a 5 x 5 Latin square design. Corn grain + poultry meal-based diets containing different levels and types of SBM (0% SBM, 18.55% conventional SBM, 18.55% low oligosaccharide SBM, 37.1% conventional SBM, 37.1% low oligosaccharide SBM) were formulated. Each period consisted of 11 d (7-d diet adaptation; 4-d collection of ileal digesta and feces). Intakes of DM, OM, CP, fat, and GE were not affected (P > .10) by treatment. Higher (P < .01) starch intakes and higher (P < .05) total dietary fiber (TDF) intakes were noted for dogs fed diets with SBM. Digestibilities of CP (P < .04) and starch (P < .002) at the ileum were higher for dogs fed the higher levels of SBM. Ileal digestibilities of most individual amino acids followed the CP response. Total tract digestibility of CP was higher (P < .006) in dogs fed the SBM diets. There were no significant differences in nutrient digestibilities between conventional and low oligosaccharide SBM. Stachyose and raffinose intakes by dogs were decreased dramatically (P < .001) as a result of substituting the low oligosaccharide SBM for conventional SBM at the higher dietary concentration, although sucrose intake by dogs fed low oligosaccharide SBM was higher (P < .001). Galactinol was present in low oligosaccharide SBM but not in conventional SBM. Total tract digestion of all oligosaccharides was near 100%. The low oligosaccharide SBM was digested as extensively, but no better than, conventional SBM.
Article
We conducted experiments to determine amino acid (AA) digestibility of nine animal by-product meals using precision-fed cecectomized roosters and ileally cannulated dogs. The products initially evaluated in roosters were meat and bone meals (MBM) containing 24 or 34% ash, poultry by-product meals (PBP) containing 7 or 16% ash, lamb meals (LM) containing 15 or 24% ash, a LM analog containing a mixture of LM and turkey meal, and two MBM processed at either a low or high temperature. The MBM and PBP differing in ash, low-ash LM, and low-temperature MBM then were incorporated into extruded dry dog foods and evaluated in cecectomized roosters and ileally cannulated dogs. True digestibility of total AA in roosters averaged 76% for the nine meals fed alone, with the low-temperature MBM being highest at 84% and the low-ash LM being lowest at 66% (P < .05). No consistent differences in rooster AA digestibility were observed between pairs of meals differing in ash content. Digestibilities of AA were higher in the low-temperature MBM than in the high-temperature MBM. Differences in rooster AA digestibility values among the six extruded dog foods containing selected animal meals were similar to those observed when the animal meals were fed alone. The ileally cannulated dog assay yielded results for AA digestibilities that were highly correlated (r = .87 to .92) with those of the rooster assay, whereby the high-ash MBM and low-temperature MBM foods had the highest mean AA digestibility at 82% and the low-ash LM food had the lowest mean AA digestibility at 62% (P < .05). Again, no consistent differences in AA digestibilities for dogs were observed between pairs of dog foods containing MBM or PBP differing in ash content. Results of this study indicated that processing temperature influenced AA digestibility of MBM, but species raw material source and ash content had no consistent effect on AA digestibility. Results also indicated that the precision-fed cecectomized rooster assay could be used to predict differences in AA digestibility among animal by-product meals for dogs.
Article
Approximately 25 to 40% of the DM in premium dog diets is animal by-product. However, limited information is available regarding the compo- sition and digestibility of these by-products, especially small intestinal digestibility. The effects of raw and rendered animal by-products incorporated into dog diets on nutrient digestion at the ileum and in the total tract were studied in this experiment. Diets fed contained various animal by-products including a rendered beef meat and bone meal (RMBM); fresh beef (FB); poultry by-product meal (PBPM); fresh poultry (FP); a plant-based control protein source, defatted soy flour (DS); and an animal-based control protein source, dehydrated whole egg (WE). The diets were extruded and kibbled. By-products varied widely in concentrations of OM, CP, amino acids, and fat. Nutrient intakes were numerically higher for FB than for all other treatments. All nutrient intakes were higher ( P < .03) for the FB treatment than for the RMBM treatment. Digestibilities of DM, OM, CP, fat, and GE at the ileum were higher ( P < .06) when dogs were fed diets containing FP than when fed diets containing PBPM. Amino acids were highly digestible at the ileum; however, digestibilities of all amino acids except cystine were higher ( P < .04) for the diets incorporating FP vs PBPM. Total tract digestion was different among treatments for DM ( P < .02), OM ( P < .01), and GE ( P < .02), and diets containing animal by-products were similar in total tract digestibility, greater than the DS control, and lower than the WE control. Rendering of poultry, but not beef, seemed to have a slight negative influence on small intestinal, but not total tract, digestibility by dogs.