Fibrillated cellulose enhances digestion in dogs_low res

1. Pet food
www.AllAboutFeed.net ALLABOUTFEED Volume 21, No. 8, 2013 19
Fibrillated cellulose
enhances digestion in dogs
Faeces volume and consistency are
indicators of the quality of dog foods.
Three independent feeding trials with
dogs show that a fibrillated, cellulose-rich
fibre lowers faeces volume, enhances
digestion and maintains optimum faeces
consistency.
By Anton C. Beynen
I
n dog food marketing health claims
are commonly used. These claims
often are not easily understood,
whereas the evidence may be loose or
unverifiable. Claims that can be
checked by dog owners are probably
more effective for determining pur-
chasing behaviour. Faeces volume and
consistency are indicators of intestinal
health and can be qualified by owners.
This communication deals with the
impact of dietary fibre type, at constant
level of dietary crude fibre, on faeces
characteristics and digestibility of
macronutrients in dogs.
Pet food and faeces
Owners often inspect the consistency
of faeces produced by their dog.
Faeces consistency is considered an
indicator of food quality in terms of
digestibility. Optimum faeces consist-
ency refers to well formed stools that
are not too moist and loose, and not
too dry and hard. Such faeces point at
adequate food digestibility and good
intestinal health. Optimum faeces
consistency is highly appreciated by
dog owners. Many owners also prefer
low faeces volume and an associated
low defecation frequency.
Faeces assessment is critical during
the process of developing pet foods.
Optimum faeces consistency contrib-
utes to the sales success of the food on
the market. In feeding trials, faeces
quality can be scored consistently and
objectively with the use of a grading
scale. Faeces can be collected quanti-
tatively and weighed to obtain an index
of volume. The degree of digestion of
macronutrients in the food can be
determined as amount of intake minus
faecal excretion and can be expressed
as percentage of intake, representing
the so-called apparent digestibility.
Type and amount of fibre
Fibre can be defined as the portion of
the plant cell wall that is resistant to the
dog’s digestive enzymes. Industrially
produced dog foods contain different
types and amounts of fibre. The fibre
component is present in core plant
ingredients or is added as a fibre-rich
feedstuff on preparation. Dietary fibres
can have different physical and physio-
logical properties. In contrast to insolu-
ble fibres, the soluble fibres form vis-
cous solutions and may be largely
degraded by the colonic microflora.
Thus, insoluble versus soluble fibres are
more recovered in faeces.
Health claims on regular dog foods or
indications for therapeutic foods may
highlight the presence of soluble or
insoluble fibre. Regarding fibre, com-
mercially prepared canine foods are
typified by their crude fibre content,
which is compulsorily listed in the guar-
anteed analysis panel on the packaging.
Crude fibre content is determined by
boiling an ether-extracted food sample
in dilute acid and then in dilute alkali.
The combustible, organic residue is the
crude fibre fraction. Analysed crude
fibre in foods contains variable fractions
of cellulose, lignin and hemicelluloses.
Clearly, crude fibre analysis yields a
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2. Pet food
www.AllAboutFeed.net20 ALLABOUTFEED Volume 21, No. 8, 2013
nonspecific outcome with little physio-
logical relevance. It is common practice
to assume that crude fibre does not
provide energy to dogs. Regular, dry
dog foods contain 2-4% crude fibre.
Light foods may contain up to 8% and
veterinary weight reduction diets have
higher levels. When expressed on a dry
matter basis, wet dog foods contain
similar concentrations of crude fibre.
Fibrillated cellulose
The Arbocel preparations of cellulose
and lignocellulose (J. Rettenmaier &
Söhne GmbH + Co KG, Rosenberg,
Germany) are natural, highly purified
products, forming a completely insolu-
ble fibre network. The cellulose-based
fibres are made by a special method to
achieve a very fine and defined particle
structure. The so-called fibrillation tech-
nique produces fibres with high capil-
lary effect and surface activity.
Arbocel BWW 40 contains only cellu-
lose. Controlled research has shown
that incorporation of the cellulose prep-
aration into chew treats ameliorates
dental disease in dogs (Beynen et al.,
2010) and that addition to the food
reduces hair ball symptoms in cats
(Beynen et al., 2011). Arbocel RC
contains 46% cellulose, 24% lignin and
16% hemicellulose; the crude fibre con-
tent is 66%. The three studies described
below demonstrate that inclusion of
Arbocel RC in dog food improves
digestion, reduces faeces volume and
maintains optimum faeces consistency.
Fibrillated cellulose versus wheat bran
Within the framework of her PhD study
at the Ludwig Maximilians University
of Munich, Ludolph (2007) has used
diets containing either wheat bran or
Arbocel RC as fibre source. Wheat bran
contains about 11% crude fibre. The
main fibres in wheat bran are hemicel-
lulose (about 28%), cellulose (about
8%) and lignin (about 5%).
Adult, female beagle dogs (n=16) with
average weight of 12.2 kg were fed the
two diets according to a cross-over
design. On a group basis, faeces were
collected quantitatively for 21 days.
The dry foods were based on corn
(42.5%) and chicken meal (14.5%).
The control diet contained 15% wheat
bran which was replaced by 2.7%
Arbocel RC, 9.3% wheat flour and 3%
greaves in the test diet. The diets
contained 3.1 and 3.2% crude fibre.
An individually determined amount of
food was provided once per day.
Acceptance was similar for the two
diets. Average weight of fresh faeces
was computed as 147 g/day for the
wheat-bran diet and 110 g/day for the
diet containing Arbocel RC; measured
dry matter contents of faeces were
27.6 and 29.0%, respectively. It was
calculated that apparent dry matter
digestibility was 2.3% units higher for
the Arbocel diet. Faeces quality was
scored on a 1-4 scale (1 = solid;
2 = optimally formed; 3 = pasta like;
4 = liquid). For the wheat-bran and the
Arbocel diet the average faecal scores
were found to be 2.3 and 2.2.
Another experiment comparing Arbocel
RC with wheat bran was carried out by
Shiva Kumar and colleagues (2012) at
Provimi Animal Nutrition India. The
control, extruded, dry food consisted of
69% cereals (wheat flour, wheat bran,
corn gluten), 20% poultry meal, 6%
fats and oils and 5% premixes. The test
diet contained 3% Arbocel RC at the
expense of wheat bran. The two diets
were iso-nitrogenous and iso-energetic;
the analysed crude fibre contents were
identical (2.1%). The diets were fed to
six adult dogs, weighing 30-42 kg. A
cross-over design with periods of 10
days was used. Food was supplied
once daily, the amount being equiva-
lent to maintenance energy require-
ments. During the last five days of
each period, faeces were collected.
Table 1 documents that the apparent
digestibilities of dry matter, crude
protein, crude fat and carbohydrates
(nitrogen-free extract) were increased
by consumption of Arbocel. The
increases are statistically significant.
Based on the mean values for amount
of food supplied and dry matter digest-
ibility, the faecal output of dry matter
was calculated. For the control diet and
the Arbocel diet, faecal excretion of dry
matter was 169 and 149 g/day. When
assuming a faecal dry matter content
of 28%, the production of fresh faeces
for the control and Arbocel diet would
be 604 and 532 g/day.
Fibrillated cellulose versus beet pulp
At the Free University of Berlin, Kröger
et al. (2011) fed eight Beagles dry foods
with similar crude fibre content, but
containing either sugar beet pulp or
Arbocel RC. Dried beet pulp contains
12-18% crude fibre, but has a high con-
tent (about 20%) of soluble fibre in the
form of pectin. The control diet con-
tained 50% rice flour, 31% poultry meal
and 12% beet pulp. The test diet con-
tained 59.8% rice flour, 30.1% poultry
meal and 2.7% Arbocel RC. The control
and test diets contained 3.1 and 2.4% of
crude fibre. The dogs received each diet
for 8-12 weeks. The amount of faeces
produced was determined daily. Faeces
collected during the last five days of
each feeding period were used to
measure digestibility of macronutrients.
The Arbocel versus beet-pulp diet sig-
nificantly reduced the amount of fresh
faeces from 168 to 94 g/day and raised
the faecal dry matter content from 29.7
to 42.3%. Thus, the output of dry faecal
matter was reduced from 50 to 40 g/
day. This indicates that Arbocel RC had
increased the digestibility of dietary dry
matter. Table 1 shows that the feeding of
Arbocel RC instead of beet pulp
increased the apparent digestibilities
of dietary organic matter and crude
protein; the differences are statistically
significant. Fat digestibility was unaf-
fected. Scores for faeces consistency,
on a 5-point scale, were 2.1 and 2.3 for
the control and test diet.
Volume and consistency
When feeding diets with similar content
of crude fibre, the intake of Arbocel RC
instead of wheat bran or beet pulp
reduces fresh faeces output in dogs.
The decrease ranged from 12 to 44%
Expt 1 Expt 2 Expt 3
700
500
600
400
300
200
100
0
WB or BP A
Figure1-InfluenceofdietaryArbocelRCondailyoutputoffreshfaeces
(g/day)bydogs.Experiments1and2:Arbocel(A)versuswheatbran(WB);
experiment3:Arbocelversusbeetpulp(BP).Withinexperiments,thedry
foodscontainedsimilaramountsofcrudefibre.
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3. Pet food
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(Figure 1). The impact of dietary fibre
type is the sum of the effects caused by
the addition of one fibre source and
omission of the other. The influence of
Arbocel RC may be specific because it
is seen in comparison with two different
fibre sources. Arbocel is not digestible
and poorly fermentable. Thus, ingested
Arbocel is excreted and higher intakes
induce higher faecal output. However,
compared with other fibre types,
Arbocel RC lowers faecal output and
maintains optimum faeces consistency.
The Arbocel-induced lowering of faeces
production is explained by the
observed increase in dry matter digest-
ibility, which in turn is caused by
increased digestibility of protein, fat
and carbohydrates. Low digestibility of
the base diet appears to enhance the
promoting effect of Arbocel on diges-
tion. The mechanism by which Arbocel
stimulates digestion is not known, but
it could relate to the formation of spe-
cific networks in the intestinal content,
leading to enhanced access of diges-
tive enzymes to their substrates.
Alternatively, wheat bran and beet pulp
may inhibit digestion.
Pet food quality, as perceived by dog
owners, relates to faeces volume and
consistency. The three studies described
here indicate that dietary fibre type is a
determinant of faeces characteristics
and digestive efficiency. This knowledge
may be implemented in pet food
formulation and production. AAF
References are available on request
from the author (beynen@freeler.nl)
Digestibility, % of intake
Experiment 1: Wheat bran Arbocel
Dry matter 84.2 86.5
Experiment 2: Wheat bran Arbocel
Dry matter 65.3 69.5
Crude protein 69.6 77.9
Crude fat 93.9 97.0
Carbohydrates 67.4 74.3
Experiment 3: Beet pulp Arbocel
Organic matter 86.7 90.4
Crude protein 82.5 85.7
Crude fat 97.6 97.7
Table 1 - Influence of dietary Arbocel RC on
group-mean apparent digestibility of dry
matter and macronutrients in dogs.Within
experiments, the dry foods contained similar
amounts of crude fibre.
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