Livestock Science 134 (2010) 143–145
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Livestock Science
j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / l i v s c i
Feeding chicory inulin to entire male pigs during the last period before
slaughter reduces skatole in digesta and backfat☆
N.P. Kjos a,⁎, M. Øverland a,b, A.K. Fauske c, H. Sørum c
a
b
c
Norwegian University of Life Sciences, P. O. Box 5003, N-1432 Ås, Norway
Aquaculture Protein Centre, CoE, P. O. Box 5003, N-1432 Ås, Norway
Norwegian School of Veterinary Science, Ullevålsveien 72, P. O. Box 8146 Dep., N-0033 Oslo, Norway
a r t i c l e
Keywords:
Entire male pigs
Chicory inulin
Skatole
Microbiotica
i n f o
a b s t r a c t
The effect of chicory inulin in diets for entire male pigs on skatole levels in colon, rectum and in
adipose tissue, and on the composition of microbiota in colon and rectum was evaluated. Entire
male pigs of the crossbreed [(Landrace × Yorkshire) × Landrace)] (n = 46; final BW = 101 kg)
were fed with a control diet or diets containing either 3, 6 or 9% chicory inulin (containing 70%
inulin) during the last four weeks before slaughter. Digesta samples for skatole analyses and for
microbiological examinations were taken from colon descendens and rectum. Backfat samples
were taken for skatole analyses. The skatole levels in adipose tissue were in general low
(0.03 μg/g fat). There was a reduction in skatole with increasing dieatary levels of inulin (linear,
P = 0.006). Skatole levels in the digesta samples were also reduced (linear, P b 0.002) by
increased dietary inclusion of inulin. Pigs fed with increasing levels of inulin showed a
reduction of enterobacteria in colon descendens (linear, P = 0.04) and rectum (linear,
P = 0.02), and a tendency towards reduced levels of Enterococcus spp in colon descendens
(linear, P = 0.09) and rectum (linear, P = 0.08). In conclusion, addition of chicory inulin in the
finishing diet is an effective method to reduce skatole levels in digesta and adipose tissue of the
entire male pigs, but the inclusion should be at least 6%, corresponding to 4.2% pure inulin.
© 2010 Elsevier B.V. All rights reserved.
1. Introduction
Skatole is a compound with a feacal-like off-odour produced
by microbes in the hindgut of pigs from the breakdown of the
amino acid tryptophan. Skatole production can be influenced
by the dietary composition, especially during the last days
before slaughter. Several studies have shown that fermentable
carbohydrates, like inulin at dietary inclusion levels of 5%
(Rideout et al., 2004) or 14% (Byrne et al., 2008) and raw potato
starch (Claus et al., 2003; Andersson et al., 2005; Zamaratskaia
et al., 2005), are effective in reducing the concentration of
skatole in the hindgut and adipose tissue. However, the optimal
inclusion level of inulin in diets for entire male pigs to obtain an
☆ This paper is part of the special issue entitled “11th International
Symposium on Digestive Physiology of Pigs”.
⁎ Corresponding author. Tel.: +47 64 96 51 00; fax: +47 64 96 51 01.
E-mail address: [email protected] (N.P. Kjos).
1871-1413/$ – see front matter © 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.livsci.2010.06.120
efficient reduction in skatole formation has not yet been
investigated. The aim of our study was, therefore, to study the
effect of increasing levels of chicory inulin in diets for entire
male pigs on skatole concentration in digesta and adipose
tissue, and to give a general view of the microbiota in the
gastrointestinal tract (GIT).
2. Materials and methods
2.1. Animals, allotment and diets
An experiment was carried out using 46 crossbred
growing–finishing pigs [(Landrace × Yorkshire) × Landrace)]
from 9 litters (initial BW 21.9 kg). Pigs were allotted to
treatments by weight and litter, and were individually fed
with each pig as one experimental unit. All pigs were fed with
the same grower diet until four weeks prior to slaughter, then
they were switched to the experimental finisher diets (from
144
N.P. Kjos et al. / Livestock Science 134 (2010) 143–145
Table 1
Composition of the experimental finisher diets, g kg−1.
Diets
Control
3% Inulin a
6% Inulin a
9% Inulin a
Chicory inulin
Barley
Wheat
Soybean meal
Molasses
Vegetable fat
Premix
0
485
250
170
15
45
35
30
456
250
170
15
45
34
60
427
250
170
15
45
33
90
399
250
170
15
45
31
a
Chicory inulin, containing 70% pure inulin.
and indole were collected at slaughter. The digesta samples
were taken from colon and rectum. Skatole and indole in
backfat and faeces were analyzed by methods described by
Gibis (1994) and Jensen and Jensen (1994), respectively. For
microbiological examinations, the intestinal contents were
diluted and plated onto selective media to identify enterobacteria, Enterococcus ssp, and lactic acid producing bacteria
(LAB), the bacterial counts from the samples were performed
according to procedures described by Garrido et al. (2004).
2.3. Statistical analyses
67.0 kg BW until slaughter at 100.5 kg BW). The dietary
treatments were: 1) a basal diet, 2) basal diet + 3% chicory
inulin, 3) basal diet + 6% chicory inulin, and 4) basal diet + 9%
chicory inulin. The chicory inulin (Raftifeed®IPE, Orafti LTD,
Belgium) contained 70% of inulin. Pigs were limit-fed twice
per day according to a feeding scale close to appetite feeding,
and had free access to water. The basal diet was comprised of
barley, wheat, and soybean meal, as shown in Table 1.
Statistical analysis was performed using the GLM procedure of SAS (1990) according to a completely randomized
block design. The model included dietary treatment, litter and
pen. Orthogonal polynomials were used to test linear
responses to increased level of chicory inulin. Significant
difference among treatments was shown as P ≤ 0.05, tendency for difference was defined as P between 0.05 and 0.10,
while not significant differences (NS) were shown as P ≥ 0.10.
2.2. Sample collection and analysis
3. Results and discussion
Adipose tissue samples from the dorsal subcutanous fat
layers in the neck region of all pigs were taken for
determination of skatole and indole. Digesta samples for
microbiological examination and determination of skatole
3.1. Skatole and indole
There were significant effects of chicory inulin on the
levels of skatole in digesta from colon and rectum, but the
Table 2
Effect of chicory inulin on skatole and indole in digesta and adipose tissue of entire male pigs.
Diets
Control
3% Inulin a
6% Inulin a
9% Inulin a
No. of pigs
Colon
Skatole, μg g DM−1
Indole, μg g DM−1
Rectum
Skatole, μg g DM−1
Indole, μg g DM−1
Adipose tissue
Skatole, μg g−1
Indole, μg g−1
11
11
12
12
39.20a
81.22
33.15ab
88.97
15.86bc
80.44
53.04a
76.11
38.37ab
90.75
24.90bc
93.01
0.041ab
0.047
0.055a
0.091
0.020bc
0.063
S.E.M. b
P-value
Linear contrast
5.41c
77.55
7.266
11.622
0.012
0.911
0.002
0.681
6.75c
85.37
8.097
14.315
0.004
0.834
0.001
0.635
0.010
0.019
0.010
0.48
0.006
0.64
S.E.M. b
P-value
Linear contrast
0.011c
0.070
c
a, b, c Means in a row with different subscript differ (P b 0.05).
a
Chicory inulin, containing 70% pure inulin.
b
Standard error of means.
c
Probability of linear contrasts with increasing levels of chicory inulin.
Table 3
Effect of chicory inulin on microbiota in digesta of entire male pigs (log cfu).
Diets
Control
3% Inulin a
6% Inulin a
9% Inulin a
No. of pigs
Colon
Enterobacteria
Enterococcus spp
Lactic acid bacteriae
Rectum
Enterobacteria
Enterococcus spp
Lactic acid bacteriae
11
11
12
12
6.634
5.579
6.151
6.675
4.437
4.988
6.436
4.843
5.945
6.006
4.240
4.657
0.217
0.439
0.543
0.121
0.19
0.17
0.042
0.092
0.17
6.394ab
5.628
6.043
6.679a
5.271
6.618
5.844b
5.045
4.182
5.672b
4.661
5.209
0.270
0.380
0.691
0.042
0.360
0.096
0.022
0.083
0.126
a, b Means in a row with different subscript differ (P b 0.05).
a
Chicory inulin, containing 70% pure inulin.
b
Standard error of means.
c
Probability of linear contrasts with increasing levels of chicory inulin.
c
N.P. Kjos et al. / Livestock Science 134 (2010) 143–145
levels of indole were not affected by the dietary treatments
(Table 2). The feeding of chicory inulin clearly reduced the
concentration of skatole in colon (linear, P = 0.002) and in
rectum (linear, P = 0.001). The addition of chicory inulin also
reduced the concentration of skatole in adipose tissue (linear,
P = 0.006), but the level of indole was not affected. The levels
of skatole in the adipose tissue of the pigs in this study were
in general low (0.03 μg/g fat in average for all pigs), compared
to the acceptable level of skatole (0.2 μg/g fat). The results
show that the addition of chicory inulin to diets is an effective
method to reduce skatole levels in digesta or adipose tissue of
entire male pigs, but a dietary inclusion of at least 6% should
be recommended. The level of 6% chicory inulin is
corresponding to 4.2% pure inulin. Earlier, Rideout et al.
(2004) found that 5% chicory inulin extract reduced skatole in
faeces of barrows, and Byrne et al. (2008) found that 25%
dried chicory root or 16% chicory inulin in diets for intact
male pigs during the last six weeks until slaughter reduced
skatole in adipose tissue. Hansen et al. (2008), found no
significant reduction of skatole in adipose tissue by feeding
10% or 13.3% dried chicory root (equivalent to 5.6 or 7.4%
chicory inulin) for one or two weeks prior to slaughter.
3.2. Microbiologial determination in the gastrointestinal tract
Pigs fed with increasing levels of chicory inulin had lower
levels of enterobacteria in colon decendens (linear, P = 0.04)
and in rectum (linear, P = 0.02) (Table 3). Chicory inulin also
tended to reduce the numbers of Enterococcus spp in colon
descendens (linear, P = 0.09) and in rectum (linear, P = 0.08).
The levels of LAB were not affected by the dietary treatments.
Lesniewska et al. (2006) found that rats fed chicory inulin and
two strains of LAB reduced the number of enterobacteria in
the GIT. The LAB may have better conditions in the GIT of pigs
fed with chicory inulin compared to enterobacteria and
enterococci, although no significant changes in the number of
LAB were found in our study. Further, it has been demonstrated that in germ free animals LAB possess antagonistic
activity against opportunistic bacteria such as Escherichia coli
and other potentially pathogenic enterobacteria (Pêna et al.,
2005). Most of the studies regarding the effect of inulin on gut
microflora have been performed with piglets, and in general
they show that inulin might have positive effects of microbial
characteristics in the GIT.
4. Conclusion
Feeding chicory inulin during the last four weeks before
slaughter resulted in a dose-dependent reduction of skatole
in digesta from colon and rectum and in adipose tissue, with
145
the best results obtained at 6% and 9% inclusion. The inclusion
of chicory inulin also reduced the population of enterobacteria in colon descendens and rectum of entire male pigs.
Conflict of interest
There are no conflicts of interest, including any financial,
personal or other relationships with other people or organizations, related to this paper.
Acknowledgement
This study was supported by grant # ES122080 “Male pigs —
feeding, husbandry and environment” from the Research
Council of Norway.
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