Growth performance, digestibility, and gut development of broiler chickens on diets with inclusion of chicory (Cichorium intybus L.)
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Growth performance, digestibility, and gut development of broiler chickens
on diets with inclusion of chicory (Cichorium intybus L.)
H. Y. Liu,1 E. Ivarsson,1 L. Jönsson, L. Holm, T. Lundh, and J. E. Lindberg2
*Department of Animal Nutrition and Management, PO Box 7024; and †Department of Anatomy,
Physiology and Biochemistry, PO Box 7011, Swedish University of Agricultural Sciences,
SE-750 07 Uppsala, Sweden
ABSTRACT A total of 256 broiler chickens (1 d old) and 60 g/kg chicory root diets. In contrast, a lower per-
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were used in a 32-d growth trial to study the effects formance and digestibility of DM, organic matter, and
of chicory (Cichorium intybus L.) forage and root in- AME as well as a thinner cecal mucosa layer were found
clusion on growth performance, digestibility, and gut for the 120 g/kg chicory forage diet (P ≤ 0.05). No diet
development. The chicory forage originated from 2 har- effects on organ parameters or on pH of cecum digesta
vests (June and September) and was included at 60 and were detected. The soluble nonstarch polysaccharides
120 g/kg. The chicory root was included alone at 60 g/ fractions of chicory forage did not have any major nega-
kg or together with chicory forage, from both harvests, tive effects on performance and gut development, and
in equal amounts (60 g/kg). The cereal-based control chicory forage from the September harvest was seen to
diet and 7 experimental diets were fed to each of 4 pens have a higher nutritional value than that from the June
of chickens (8 chickens/pen). A higher BW gain and harvest. Thus, results from the current study suggest
lower feed conversion ratio were found at 13 d of age in that chicory forage is a potentially useful fiber-rich feed
chickens fed the 60 g/kg chicory forage diet (P ≤ 0.05), ingredient with high palatability for broiler chickens.
whereas performance did not differ between the control
Key words: chicory, dietary fiber, gut development, digestibility, broiler chicken
2011 Poultry Science 90:815–823
doi:10.3382/ps.2010-01181
INTRODUCTION their chemical properties (Bach knudsen, 2001). For
example, high-methylated citrus pectin increases diges-
Recent studies have shown that chickens require fiber ta viscosity but the low-methylated forms do not. Thus,
in the diet to stimulate the development of the up- chickens fed diets with low-methylated citrus pectin
per gastrointestinal (GI) tract (Hetland et al., 2004; maintain performance and show no major change in
González-Alvarado et al., 2008). However, it is also intestinal environment (Langhout and Schutte, 1996;
known that inclusion of fiber in poultry diet is associ- Langhout et al., 1999). Whereas soluble NSP can be
ated with negative effects on performance, digestibil- digested to some extent in chickens (Carré et al., 1990),
ity, and health (Choct and Annison, 1992). The detri- insoluble NSP is poorly digested and mainly acts as
mental effect is mainly related to the soluble nonstarch bulk in the diet. Despite this, the inclusion of insolu-
polysaccharide (NSP) components in the dietary fiber ble NSP has been shown to improve feed utilization in
fraction and increased digesta viscosity in the intes- chickens (González-Alvarado et al., 2007; kalmendal et
tine (Bedford and Classen, 1992). Soluble NSP, such as al., 2011).
β-glucans in barley, arabinoxylans in wheat, and pectin Chicory (Cicorium intybus L.) is a perennial herb
in citrus pulp and beet pulp, all have viscous properties used as a palatable forage crop for sheep, deer, and
and have been shown to impair chicken performance cattle (Li and kemp, 2005). Recent studies in weaned
when included in the diet (Hesselman and Åman, 1986; pigs have shown high feed intake and growth perfor-
Choct and Annison, 1992; Langhout et al., 1999). How- mance on cereal-based diets with chicory forage inclu-
ever, the negative effect of fiber sources varies with sion, with only minor negative effects on nutrient and
energy digestibility (Ivarsson et al., 2011). The chicory
©2011 Poultry Science Association Inc. forage has a high content of uronic acids, which in di-
Received October 12, 2010. cotyledonous plants derive from galactosyl uronic acid;
Accepted January 8, 2011.
1 These authors contributed equally to this work. uronic acid is the building block in pectin (Voragen et
2 Corresponding author: jan.erik.lindberg@slu.se al., 2001). The chicory root has a high content of fruc-
815816 Liu et al.
tooligosaccharides and inulin, which can be used to ma- vegetative stage in June and September (the 2 harvests
nipulate the composition of microflora in the gut and selected were the first and third among 3 consecutive
enhance its integrity (Flickinger et al., 2003). Inulin is harvests) from the same field with a stubble height of
one of the best-studied prebiotic sources in domestic approximately 5 cm, dried indoors at 30°C with forced
animal application (Castellini et al., 2007). Thus, both air for 1 wk, and milled through a 3-mm screen before
the forage and the root of chicory are of interest as fiber mixing with the other feed ingredients. The diets were
sources in poultry nutrition. given as pellets throughout the experiment except for
The present study aimed to explore the effects on the first 7 d, when the pellets were ground before giv-
growth performance, nutrient digestibility, and gut ing to the chicks. All diets contained 5 g/kg of titanium
development when chicory fiber in the form of forage dioxide as indigestible digesta marker. None of the diets
and root was included in a cereal-based diet for broiler contained coccidiostats.
chickens.
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Chicken Performance and Excreta
MATERIALS AND METHODS
Collection
Birds and Housing
Body weight and feed intake (FI) were registered by
A total of 256 male and female 1-d-old broiler chick- pen at arrival and on d 6, 13, 20, and 27. Feed conver-
ens (Ross 308) with an initial BW of 44.0 ± 15.1 g sion ratio (FCR) was calculated and corrected for mor-
was included in the experiment. They were randomly tality. The performance is presented for the first phase
distributed into 32 pens (1.50 × 0.75 m) with initially 8 (0–13 d) and for the overall experiment (0–27 d). Fresh
chickens/pen. During the first week of the experiment, excreta samples for determination of digestibility were
4 weak and dead birds from 4 different diets were re- collected from each pen once daily from d 27 to 30 and
placed. Wood shavings were used as litter from d 1 to stored at −20°C until analysis was carried out.
27. During an excreta collection period, between d 27
and 30, the chickens were kept on a net floor. The birds
had free access to water and feed throughout the ex- Tissue Sampling and Morphological
periment. Room temperature was gradually decreased Examination
from 34°C on d 0 to 21°C on d 25 and kept at 21°C until
the chickens were sent for slaughter. The chickens had On d 31, 1 chicken was randomly selected from each
continuous artificial light for the first 3 d; thereafter, pen and killed by an intravenous injection of sodium
the dark period was gradually increased to 5 h from d pentobarbital through the wing vein. The birds were
13 to age to slaughter. The experiment was carried out immediately dissected. One segment of tissue (3 cm)
at Funbo-Lövsta Research Centre (Uppsala, Sweden) from the proximal cecum and 1 segment at around 20
and was approved by the ethical committee of the Upp- cm from the duodenal loop (jejunum) were collected.
sala region. Samples were rinsed in PBS (0.01 M, pH 7.4) to remove
digesta and placed in 4% phosphate-buffered paraform-
Experimental Diets aldehyde (0.067 M, pH 7.2) fixative for 48 h. The tissue
segments were then trimmed and embedded in paraffin
Diets were formulated to meet the nutritional require- according to standard procedures.
ments of the chickens according to NRC (1994; Table 1). Embedded tissue samples were cut to a thickness of 4
However, because the CP content in the diets was kept µm, stained with hematoxylin and eosin, and examined
constant throughout the study, the dietary content was using a light microscope (Nikon Microphot-FXA mi-
lower than recommended during the first phase of this croscope, Bergström Instrument AB, Stockholm, Swe-
study. A total of 8 diets were formulated, 1 cereal-based den) equipped with image analysis software (Eclipsenet
control diet (C) and 7 experimental diets, with part of 1.20.0, Nikon Instruments, Melville, NY). The slides
the cereal substituted with the following (Table 2): 60 were coded and all measurements were made by an indi-
g/kg of air-dried chicory forage from either the June vidual using the 10× objective lens. Villus height, crypt
harvest (CF160) or the September harvest (CF260); depth, and the thickness of the muscularis externa at
60 g/kg of chicory root (Inulin-60, which is produced by counterpart locations were evaluated on 10 well-orien-
indirect drying of chicory root, milled to a powder con- tated villus and crypt preparations from the jejunum.
taining 60% inulin; Inter-Harz GmbH, Klein Offenseth- Measurements were made only where the villus-crypt
Sparrieshoop, Germany; CR60); 120 g/kg of air-dried unit was perpendicular to the muscularis mucosa. The
chicory forage from either the June harvest (CF1120) villus height was depicted as the distance from the top
or the September harvest (CF2120); a mix of 60 g/ of the villus to the villus-crypt junction. The total mu-
kg of chicory forage from the June harvest and 60 g/ cosal thickness was measured from the top of the villus
kg of Inulin-60 (CF1R); and a mix of 60 g/kg chicory to the border over the muscularis mucosa. The depth
forage from the September harvest and 60 g/kg of Inu- of crypt was then defined as the difference between
lin-60 (CF2R). Chicory forage was harvested at the the total mucosal thickness and the villus height. TheEFFECTS OF CHICORY INCLUSION ON BROILERS 817
Table 1. Ingredient composition (g/kg) of control and experimental diets1
Item C CF160 CF260 CR60 CF1120 CF2120 CF1R CF2R
Wheat 550 507.5 507.5 507.5 460 460 460 460
Inulin-602 0 0 0 60 0 0 60 60
Soybean meal 160 160 160 160 160 160 160 160
Barley 187.5 170 170 170 157.5 157.5 157.5 157.5
Fish meal 20 20 20 20 20 20 20 20
Vegetable fat3 30 30 30 30 30 30 30 30
NaCl 3 3 3 3 3 3 3 3
Chicory (June) 0 60 0 0 120 0 60 0
Chicory (September) 0 0 60 0 0 120 0 60
l-Lysine 3.5 4 4 3.7 4 4 4 4
Monocalcium phosphate 18 17.5 17.5 17.8 17.5 17.5 17.5 17.5
Calcium carbonate 20 19.5 19.5 20 19.5 19.5 19.5 19.5
dl-Methionine 4 4.5 4.5 4.5 4.5 4.5 4.5 4.5
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Premix4 2 2 2 2 2 2 2 2
Titanium dioxide 5 5 5 5 5 5 5 5
1C: control. CF 60: 60 g/kg of chicory forage from June harvest. CF 60: 60 g/kg of chicory forage from September harvest. CR60: 60 g/kg of chicory
1 2
root. CF1120: 120 g/kg of chicory forage from June harvest. CF2120: 120 g/kg of chicory forage from September harvest. CF1R: mix of chicory forage
from June harvest and chicory root. CF2R: mix of chicory forage from September harvest and chicory root.
2Produced by indirect drying of chicory root, milled to a powder containing 60% of inulin (Inter-Harz GmbH, Klein Offenseth-Sparrieshoop, Ger-
many).
3Liquid vegetable fat comprising a mixture of fatty acids (AkoFeed Standard, AkoFeed, Karlshamn, Sweden).
4Supplemented per kilogram of feed: vitamin A (all-trans retinol), 12,000 IU; vitamin D , 5,000 IU; vitamin E (dl-α-tocopheryl acetate), 70 IU;
3
vitamin K3, 4 mg; vitamin B1, 3 mg; vitamin B2, 8 mg; vitamin B6, 5 mg; vitamin B12, 0.02 mg; pantothenic acid, 20 mg; folic acid, 2 mg; niacin, 60
mg; biotin, 0.175 mg; iron, 20 mg; copper, 15 mg; cobalt, 0.25 mg; manganese, 70 mg; zinc, 70 mg; iodine, 1 mg; selenium, 0.035 mg; molybdenum,
0.50 mg.
thickness of the muscularis externa, which consists of chicken was randomly selected and weighed and the en-
an inner circular layer and a longitudinal outer muscu- tire GI tract was removed. Immediately, pH was mea-
lar layer, was measured. For cecum, the thickness of the sured in the cecal content (1 side randomly). The length
mucosa and the muscularis externa were measured. and weight of the small intestine and the counterpart
cecum were registered after removal of digesta, and the
Digestive Organ Measurement and pH gizzard was weighed. The proportion of organ to BW
of Digesta was calculated for each organ from each chicken. Ileal
digesta between 5 cm posterior of Meckel’s diverticulum
On d 32, the remaining chickens, 1 pen at a time, were and the ileo-cecal-colonic junction were pooled from the
transported to the facility’s slaughter house, stunned additional 2 to 5 birds within replicates, placed on ice
by electricity, and killed by bleeding. From each pen 1 immediately, and stored at −20°C until analysis.
Table 2. Analyzed chemical composition (g/kg of DM) and gross energy content (kcal/kg of DM) of control and experimental diets1
and chicory forage from June (CF1) and September (CF2) harvests
Item C CF160 CF260 CR60 CF1120 CF2120 CF1R CF2R CF1 CF2
Ash 74 80 82 74 83 94 81 84 149 198
CP 197 201 204 192 191 201 194 190 137 144
Nonstarch polysaccharides
Total 152 174 166 147 172 177 153 147 434 400
Insoluble 114 121 122 110 125 118 113 103 265 206
Arabinose
Total 24 28 23 23 21 22 21 21 19 19
Insoluble 18 17 17 17 17 16 16 15 9 7
Xylose
Total 40 39 36 36 35 33 33 30 50 24
Insoluble 35 32 35 31 34 30 30 26 49 23
Uronic acid
Total 18 25 29 17 35 39 29 30 165 177
Insoluble 8 9 9 9 10 10 10 10 26 22
Klason lignin 19 20 25 12 26 16 24 23 100 92
Dietary fiber 171 174 191 159 198 193 177 170 534 492
Fructan 20 21 21 54 19 17 48 45 4 5
Gross energy 4,296 4,272 4,248 4,248 4,224 4,200 4,248 4,200 3,696 3,528
1C: control. CF 60: 60 g/kg of chicory forage from June harvest. CF 60: 60 g/kg of chicory forage from September harvest. CR60: 60 g/kg of chicory
1 2
root. CF1120: 120 g/kg of chicory forage from June harvest. CF2120: 120 g/kg of chicory forage from September harvest. CF1R: mix of chicory forage
from June harvest and chicory root. CF2R: mix of chicory forage from September harvest and chicory root.818 Liu et al.
Chemical Analysis values from each chicken were used for histology analy-
sis, whereas individual values from each pen were used
Samples were analyzed for DM by drying at 103°C for for organ measurements. The results were presented as
16 h and for ash after ignition at 600°C for 3 h (Jennis- the least squares means value ± SEM. To assess the
che and Larsson, 1990). Crude protein (N × 6.25) was effect of fiber level (CF60 vs. C; CF120 vs. C; CF60
determined by the Kjeldahl method (Nordic Commit- vs. CF120), fiber source (CR60 vs. C; CR60 vs. CF60;
tee on Feed Analysis, 2003) using a Kjeltec Auto 1030 CFR vs. CF120), and time of harvest (CF1 vs. CF2),
analyzer (Tecator AB, Höganäs, Sweden). Crude fat linear contrasts were calculated involving average value
was determined according to European Communities of each comparison. All differences were considered sig-
(1984) using a hydrolyzing unit (Soxtec System 1047 nificant at P ≤ 0.05.
Hydrolysing Unit, Tecator AB) and an extraction unit
(Soxtec System HT6, Tecator AB). Total NSP and con-
stituent sugars, Klason lignin, and total dietary fiber RESULTS
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were determined according to Bach Knudsen (1997).
Fructan content was determined according to AOAC Performance
(2000) method 999.03 using Fructan Assay Kit (cat. no.
K-FRUC, Megazyme, Bray County, UK). Gross energy Chicken BW gain was affected by diets during the
was measured with a bomb calorimeter (6300 Oxygen first phase (d 0–13, P ≤ 0.001) but not during the
Bomb Calorimeter, Parr, Moline, IL). Titanium dioxide overall period (d 0–27; Table 3). Thus, the final BW (d
was analyzed according to Short et al. (1996). 27 of age) was not affected by diets (data not shown).
No effects of diets were seen on FI. However, FCR val-
ues on d 13 and 27 differed between diets (P ≤ 0.05).
Calculations With respect to fiber level, chickens fed diet CF60 had
Dietary fiber was calculated as total NSP + lignin. a higher BW gain at the first period compared with
The total tract apparent digestibility (TTAD) and il- those fed diet C and diet CF120 and a lower FCR than
eal apparent digestibility (IAD) were calculated using chickens fed diet CF120 (P ≤ 0.01). On d 27, FCR was
the indicator technique (Sauer et al., 2000) according higher (P ≤ 0.05) in the CF120 group than in the C
to the equation and CF60 groups. Regarding fiber sources, at 13 d of
age BW gain was higher and FCR was lower in chickens
fed diet CF60 compared with those fed diet CR60 (P ≤
TTAD or IAD =
0.001). The FCR was higher (P ≤ 0.05) in chickens fed
[1 − (IT × DCexc):(DCT × Iexc)] × 100, diet CR60 than in those fed diets CF60 and C at 13 and
27 d of age, respectively. Harvest also affected BW gain
where IT is the indicator concentration in the exper- and FCR at the first phase (d 0–13), where chickens fed
imental diet (g/kg), DCexc is the dietary component diet CF2 had a higher BW gain (P ≤ 0.01) and lower
concentration in excreta or ileal digesta (g/kg), DCT is FCR (P ≤ 0.05) than those fed diet CF1.
the dietary component concentration in the experimen-
tal diet (g/kg), and Iexc is the indicator concentration Digestibility and AME
in excreta or ileal digesta (g/kg).
The AME content (kcal/kg of DM) was calculated Diet affected (P ≤ 0.05) the TTAD of DM, organic
as matter (OM), energy, all fiber components, and the
IAD of CP (Table 4). Fiber level influenced the TTAD
AME = gross energydiet × CTTAD of energyexcreta, of all dietary components. The TTAD of DM and OM
were higher (P ≤ 0.05) for diet C than for diet CF60.
where gross energydiet is the dietary gross energy con- Also, diet C had a higher (P ≤ 0.05) TTAD than diet
tent (kcal/kg of DM) and CTTAD of energyexcreta is CF120 for all dietary components. Diet CF60 had a
the coefficient of TTAD of gross energy. higher (P ≤ 0.05) TTAD for all dietary components,
except for OM, than diet CF120. Fiber source influ-
Statistical Analysis enced the digestibility of all dietary components except
the TTAD of xylose. The TTAD of DM, OM, and ener-
Statistical analysis was performed with the GLM pro- gy were higher (P ≤ 0.05) in diet C than in diet CR60.
cedure in SAS (version 9.1, SAS Institute, Cary, NC) The TTAD of arabinose and uronic acid was lower (P
to determine dietary effect by one-way ANOVA. The ≤ 0.05) for diet CR60 than for diets C and CF60. The
experiment was structured as a randomized complete TTAD of NSP was higher (P ≤ 0.05) in diet CF120
block design with 8 treatments in 4 blocks. The mod- than in diet CFR. The TTAD of fiber components was
el included diet (C, CF160, CF260, CF1120, CF2120, different between harvests. Diet CF2 had a higher (P
CR60, CF1R, and CF2R) as the fixed factor. The pen ≤ 0.05) TTAD of arabinose and uronic acid than diet
served as the experimental unit for performance and CF1.The IAD of CP was higher in diets C and CR60
digestibility data. Means of 10 villus and crypt unit than in diet CF60 (P ≤ 0.05), but no difference wasEFFECTS OF CHICORY INCLUSION ON BROILERS 819
observed between the other dietary components. The
harvest. CF2120: 120 g/kg of chicory forage from September harvest. CF1R: mix of chicory forage from June harvest and chicory root. CF2R: mix of chicory forage from September harvest and chicory
control. CF160: 60 g/kg of chicory forage from June harvest. CF260: 60 g/kg of chicory forage from September harvest. CR60: 60 g/kg of chicory root. CF1120: 120 g/kg of chicory forage from June
Table 3. Effects of fiber level, fiber source, and time of harvest on BW gain, feed intake (FI), and feed conversion ratio (FCR; feed intake:BW gain) at first phase (0–13 d) and
harvest:
Time of
CF1 vs.
AME decreased with increasing fiber level (P ≤ 0.05)
CF2
NS
**
*
and was affected by fiber source; it was lower (P ≤
0.05) in diet CR60 than in diet C.
CF120
CFR
NS
NS
NS
vs.
Fiber source
Cecal Content pH, Digestive Organ, and Gut
CR60
CF60
Morphology Parameters
***
vs.
**
*
No significant differences were observed in organ pa-
CR60
C vs.
P-value
NS
NS
**
rameters or in pH value of cecal digesta (Table 5). Je-
junum morphology was not affected by diet (data not
shown), whereas cecum morphology was affected (P ≤
CF120
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CF60
0.05). The cecum mucosal thickness decreased with in-
***
***
vs.
*
creasing level of fiber. Chickens in the C group had a
Fiber level
thicker mucosal layer (P ≤ 0.01) of cecum than those
CF120
C vs.
fed diets CF60 and CF120 (Table 5).
NS
NS
**
DISCUSSION
CF60
C vs.
NS
NS
**
This is the first study using chicory forage as a fiber
0.03
0.06
35.6
64.1
19.4
10.4
SE
source in chicken diets. The results indicate that this
fiber source can be included in a cereal-based diet for
broiler chickens at the level of 120 g/kg, over a growth
1.67
1.48
CF2R
period of 27 d, without impairing the final BW com-
1,206
2,019
496
4
336
pared with the breed standard but resulting in higher
feed intake and poorer FCR (Ross, 2007). During the
1.66
1.63
first phase of the study (d 0–13) a reduction in BW
CF1R
1,260
2,089
506
4
311
gain and an increase in FCR were found compared with
the expected performance of the breed standard (Ross,
2007) when chicory forage content in the diet increased.
*P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001. Only contrasts with significance are shown in the table.
1.70
1.57
CF2120
This may be attributed to the use of a single feed,
1,294
2,202
528
4
338
with high dietary fiber content, during the entire rear-
ing period. Moreover, the CP content of the diet used
was lower than recommended (NRC, 1994) during the
1.75
1.78
CF1120
first phase of this study. It should also be noted that a
1,255
2,199
544
4
306
high feed spoilage was observed during the first phase
Diet2
of this study.
The maintained BW gain for the total rearing period,
1.75
1.67
CR60
irrespective of fiber source and fiber level, can be attrib-
1,183
2,067
522
4
313
uted to an increase in gut fill or organ weight or both
and may not necessarily reflect an increase in the car-
1.67
1.36
cass weight. A higher fiber intake will result in a larger
CF260
1,307
2,188
527
4
388
proportion of the diet being fermented, with a subse-
quent reduction in the net energy content (Jørgensen et
are least squares means ± pooled SE.
al., 1996; Jamroz et al., 2002). Thus, energy available
1.65
1.48
CF160
for body growth in the current study should be ex-
1,287
2,118
514
4
347
pected to decrease with increasing fiber level. Previous
studies have shown that increased gut fill (Hetland and
Svihus, 2001; Kalmendal et al., 2011) or increased gut
1.60
1.54
overall experiment (0–27 d)1
organ weights or both (Jørgensen et al., 1996; Hetland
1,287
2,058
513
4
332
C
and Svihus, 2001; González-Alvarado et al., 2008) may
explain unchanged BW gain in chickens fed fiber-rich
diets. Gut fill was not recorded in the current study,
BW gain (g/bird)
BW gain (g/bird)
Experiment overall
but GI tract weights and lengths were recorded, and
they did not differ between diets. The lack of effect on
FI (g/bird)
FI (g/bird)
First phase
GI tract weights could be attributed to differences in
1Values
Pens (n)
the basal diet composition between studies. In the cur-
FCR
FCR
2C:
root.
Item
rent study, the cereal-based C diet was already high in820 Liu et al.
fiber content and substitution of cereal to chicory may
harvest. CF2120: 120 g/kg of chicory forage from September harvest. CF1R: mix of chicory forage from June harvest and chicory root. CF2R: mix of chicory forage from September harvest and chicory
control. CF160: 60 g/kg of chicory forage from June harvest. CF260: 60 g/kg of chicory forage from September harvest. CR60: 60 g/kg of chicory root. CF1120: 120 g/kg of chicory forage from June
harvest:
Time of
CF1 vs.
not have had any major effect on GI tract growth. In
CF2
NS
NS
NS
NS
NS
NS
NS
*
*
contrast, if the basal diet contains starch (Hetland and
Svihus, 2001) or sepiolite (a complex magnesium sili-
cate added as an inert material; González-Alvarado et
CF120
CFR
NS
NS
NS
NS
NS
NS
NS
NS
vs.
*
al., 2007), which is substituted by different fiber source,
it will result in a greater change in diet fiber content
Fiber source
and dietary properties (Bach Knudsen, 2001).
CR60
CF60
NS
NS
NS
NS
NS
NS
vs.
**
**
**
Insoluble NSP have been shown to increase digesta
passage rate in poultry and thereby increase the FI
CR60
P-value
C vs.
(Hetland et al., 2004; Kalmendal et al., 2011), whereas
***
NS
NS
NS
**
*
*
*
*
soluble NSP have been shown to increase digesta vis-
cosity, decrease water absorption, increase water intake,
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Table 4. Effects of fiber level, fiber source, and time of harvest on total tract apparent digestibility variables of birds fed experimental diets1
and reduce FI (van der Klis et al., 1993). Inclusion of
CF120
CF60
chicory forage and root in the diet increased dietary to-
***
***
NS
NS
vs.
**
**
*
*
*
tal fiber content as well as the content of both insoluble
Fiber level
and soluble NSP. However, no dietary treatment effect
CF120
C vs.
on FI was observed in the current study. Although the
***
***
***
***
***
***
NS
**
*
viscosity of digesta was not measured, the good growth
performance and high FI indicated that the soluble
CF60
C vs.
NSP fractions in chicory forage did not cause any ma-
NS
NS
NS
NS
NS
*
*
*
*
jor viscosity problems.
Improved feed utilization (FCR) was seen at 13 d
0.96
0.85
2.64
2.69
2.49
4.17
1.76
0.77
32.56
SE
of age in chickens fed diet CF60 compared with those
fed diet CF120, whereas the FCR was comparable be-
tween the C and CF120 diets. Recently, Kalmendal et
66.7
68.8
17.5
18.8
15.4
29.5
77.5
69.6
CF2R
4
2,915
al. (2011) reported that 30% inclusion of sunflower cake
(a high-fiber feed ingredient) in a cereal-based diet for
broiler chickens impaired FCR, but 20% inclusion did
65.3
67.8
18.4
17.2
16.0
31.2
75.8
68.9
CF1R
4
2,918
not. This suggests that there may be critical dietary
fiber-specific inclusion levels for chickens of different
ages.
CF2120
65.5
69.0
26.6
24.4
19.9
36.2
74.3
70.2
4
2,930
*P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001. Only contrasts with significance are shown in table.
In the current study, chickens fed chicory forage
harvested in September (CF2) had a better perfor-
mance than chickens fed chicory forage harvested in
CF1120
66.0
69.0
21.0
12.4
13.1
30.0
76.4
69.4
4
2,925
June (CF1). This could not be supported by improved
Diet2
TTAD of dietary components and energy. However,
differences in dietary chemical composition may affect
67.7
70.0
25.5
23.0
23.0
24.6
81.1
71.0
CR60
4
3,010
nutrient and energy utilization at gut level, which can
have an effect of performance (Bedford and Classen,
1992; Choct and Annison, 1992). Thus, we suggest that
68.8
71.5
31.1
31.0
26.4
49.1
72.6
72.9
CF260
4
3,091
the better performance could be attributable to differ-
ences in chemical composition between chicory forage
from the 2 harvests, with higher CP and soluble NSP
67.1
69.7
29.1
37.1
21.2
37.5
74.7
71.0
CF160
4
3,024
content and lower lignin content in the September har-
are least squares means ± pooled SE.
vest (CF2) than in the June harvest (CF1).
Fiber level affected the digestibility of DM, OM, and
70.6
73.0
31.2
31.0
28.5
48.0
79.4
73.8
4
3,163
C
AME, with lower TTAD and AME for diet CF120.
However, the numerical difference in TTAD of OM (73
vs.71) was in the same range as reported (68 vs. 66)
Ileal apparent digestibility of CP
when low-methylated (low viscosity) citrus pectin was
included in a maize-based diet, but lower than reported
Nonstarch polysaccharides
(68 vs. 57) with inclusion of high-methylated (high vis-
AME (kcal/kg of DM)
cosity) citrus pectin (Langhout et al., 1999). This sup-
ports our contention that the soluble NSP in chicory
Organic matter
forage do not have a major effect on digesta viscosity.
Uronic acids
The TTAD of total NSP in the present study was on
Arabinose
1Values
Pens (n)
Energy
average 25.1, with the highest value for the C diet. The
Xylose
2C:
root.
Item
DM
digestibility values were in the same range as reportedEFFECTS OF CHICORY INCLUSION ON BROILERS 821
by Jørgensen et al. (1996). Clear effects on NSP di-
harvest. CF2120: 120 g/kg of chicory forage from September harvest. CF1R: mix of chicory forage from June harvest and chicory root. CF2R: mix of chicory forage from September harvest and chicory
control. CF160: 60 g/kg of chicory forage from June harvest. CF260: 60 g/kg of chicory forage from September harvest. CR60: 60 g/kg of chicory root. CF1120: 120 g/kg of chicory forage from June
harvest:
Time of
CF1 vs.
gestibility of both inclusion level and fiber source were
CF2
NS
observed. A lower NSP digestibility compared with the
C diet was observed in diets with the highest inclusion
(120 g/kg) of chicory forage (diet CF120) and in diets
CF120
CFR
NS
vs.
with inclusion of chicory root (diets CR60 and CFR).
However, no reduction in NSP digestibility was found
Fiber source
Table 5. Effects of fiber level, fiber source, and time of harvest on cecum mucosa thickness, relative organ weight, organ length, and pH in digesta from cecum1
for diets with the lower inclusion (60 g/kg) of chicory
CR60
CF60
NS
vs.
forage (diet CF60). These results implied that NSP can
be used to some extent in broiler chickens and that
thresholds exist for NSP inclusion in the diet, which
P-value
CR60
C vs.
NS
may differ between NSP sources. The TTAD of NSP in
the chicory forage diet was higher than the TTAD in
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chicory root diets (diet CR60). It seems that the fiber
CF120
fractions in chicory forage and the cereal-based C diet,
CF60
NS
vs.
which chemically differ from inulin, are more digestible.
In the present study, uronic acid was the NSP compo-
Fiber level
nent that showed the highest digestibility values, which
CF120
C vs.
***
differed most in content and composition between the
diets. In monocotyledonous plants, like cereals, uronic
acids derive from glucuronic acid (Schooneveld-Berg-
CF60
C vs.
**
mans et al., 1999), whereas uronic acids in dicotyledon-
ous plants, like chicory, derive from galacturonic acids,
0.02
0.88
0.14
the building block in pectin (Barry, 1998; Voragen et
0.3
9.6
1.0
SE
16
al., 2001). Inclusion of 60 g/kg of chicory forage in-
creased the uronic acid content in the diet by factor
0.24
CF2R
5.8
10.3
3.4
1.5 and changed the uronic acid composition of the diet
190
18
4
318
without depressing the digestibility. However, inclusion
of 120 g/kg of chicory forage had a negative influence
0.27
CF1R
5.9
13.0
3.1
184
19
4
285
on the TTAD of uronic acid. Jørgensen et al. (1996)
found that the digestibility of uronic acid decreased
CF2120
0.27
when the inclusion level of pea fiber in diets for broil-
5.7
10.7
3.2
186
20
4
281
er chickens was increased from 187 to 375 g/kg. This
clearly indicates that the capacity of broiler chickens to
CF1120
digest galacturonic acids is highly dependent on the in-
0.26
6.1
10.0
3.2
179
19
4
290
clusion level. Harvest time of chicory forage also influ-
**P ≤ 0.01; ***P ≤ 0.001. Only contrasts with significance are shown in table.
Diet2
enced the TTAD of uronic acids, with higher values for
the September harvest (CF2) than for the June harvest
0.25
CR60
5.4
10.8
2.9
179
20
4
331
(CF1). This can be explained by the different propor-
tions of insoluble and soluble uronic acid between the 2
0.27
CF260
harvests, with a higher content of soluble uronic acid in
5.9
12.2
3.1
184
19
4
309
the September harvest than in the June harvest.
The IAD of CP was lower in diets with the low in-
0.21
CF160
clusion level (60 g/kg) of chicory forage (diet CF60)
6.3
12.9
3.1
200
19
4
310
compared with C, whereas no differences in IAD of CP
are least squares means ± pooled SE.
were observed between C and the other diets. This may
0.22
6.0
12.5
3.1
be attributed to higher microbial activity in the gut in
C
184
17
4
376
diet CF60, reflected by a higher NSP digestibility and
a consequently reduced IAD value.
Relative organ weight (g/kg of BW)
In chickens, a lowered pH in the ceca is an indication
of increased short-chain fatty acid (SCFA) production
Cecum mucosa thickness (µm)
(van der Wielen et al., 2000). A high fiber inclusion in
the diet should be expected to increase microbial fer-
mentation in the gut and consequently affect the con-
pH of cecal digesta
Organ length (cm)
tent of SCFA and pH (Jørgensen et al., 1996; Langhout
Small intestine
Small intestine
and Schutte, 1996). However, in broiler chickens fed a
diet with inclusion of inulin, no change in total SCFA
1Values
Gizzard
Pens (n)
Cecum
Cecum
concentration was found in cecal digesta (Rehman et
2C:
root.
Item
al., 2008). In the current study the cecal pH was not822 Liu et al.
significantly affected by fiber inclusion level. This may Carré, B., L. Derouet, and B. Leclercq. 1990. The digestibility of
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diet CF160 (0.9 units). tion by wheat pentosans. Br. J. Nutr. 67:123–132.
Chun, W., T. Bamba, and S. Hosda. 1989. Effect of pectin, a soluble
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largement of villus height or crypt depth in the small small intestine in rats. Digestion 42:22–29.
intestine in monogastric animals that have ingested European Communities. 1984. Determination of crude oils and fat.
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GI tract rather than in the proximal part (Brunsgaard and digestive traits of broilers. Poult. Sci. 86:1705–1715.
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