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-

                                                            815
816                                                    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. The
EFFECTS 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 was
EFFECTS 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 in
820                                                                                                                                                                                                                                                                                                                                                                                                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,

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           Downloaded from https://academic.oup.com/ps/article-abstract/90/4/815/1515579 by guest on 17 November 2019
 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 reported
EFFECTS 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

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      Downloaded from https://academic.oup.com/ps/article-abstract/90/4/815/1515579 by guest on 17 November 2019
                                                                                                                                                                                                                                                                                                                                                                                                                                                         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 not
822                                                           Liu et al.

significantly affected by fiber inclusion level. This may             Carré, B., L. Derouet, and B. Leclercq. 1990. The digestibility of
partly be attributed to a high content of fiber in the                   cell-wall polysaccharides from wheat (bran or whole grain), soy-
                                                                         bean meal, and white lupin meal in cockerels, muscovy ducks,
C diet and therefore a limited effect on SCFA content,                   and rats. Poult. Sci. 69:623–633.
but could also be attributed to the limited number of                 Castellini, C., R. Cardinalia, P. G. Rebollar, A. Dal Bosco, V. Ji-
replicates in combination with high individual varia-                    meno, and M. E. Cossu. 2007. Feeding fresh chicory (Cichorium
                                                                         intybus) to young rabbits: Performance, development of gastro-
tion. It should be noted that a large numerical differ-                  intestinal tract and immune functions of appendix and peyer’s
ence in pH existed between chickens fed diets CR60 and                   patch. Anim. Feed Sci. Technol. 134:56–65.
C (0.6 units) and between chickens fed diets CR60 and                 Choct, M., and G. Annison. 1992. The inhibition of nutrient diges-
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
   Notably, several studies have shown significant en-                   dietary fiber, on functional and morphological parameters of the
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.
various dietary NSP sources (Sigleo et al., 1984; Chun                   Method B. Off. J. L257:23–25.

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                                                                      Flickinger, E. A., J. Van Loo, and G. C. Fahey. 2003. Nutritional
et al., 1989; Meehye, 2002; Kleessen et al., 2003; Reh-                  responses to the presence of inulin and oligofructose in the diets
man et al., 2007). In contrast, no changes were found in                 of domesticated animals: A review. Crit. Rev. Food Sci. Nutr.
villus height or crypt depth in the jejunum of broilers in               43:19–60.
the current study. This may be because the physiological              González-Alvarado, J. M., E. Jiménez-Moreno, R. Lázaro, and G. C.
                                                                         Mateos. 2007. Effect of type of cereal, heat processing of the ce-
effect of dietary fiber is more pronounced in the distal                 real, and inclusion of fiber in the diet on productive performance
GI tract rather than in the proximal part (Brunsgaard                    and digestive traits of broilers. Poult. Sci. 86:1705–1715.
and Eggum, 1995). The ceca are recognized as the key                  Gonzalez-Alvarado, J. M., E. Jimenez-Moreno, D. G. Valencia, R.
site of fermentation in the poultry gut and interact ac-                 Lazaro, and G. G. Mateos. 2008. Effects of fiber source and heat
                                                                         processing of the cereal on the development and pH of the gastro-
tively with the microbiota (Józefiak et al., 2004). In the               intestinal tract of broilers fed diets based on corn or rice. Poult.
present study, thinner cecal mucosa was observed with                    Sci. 87: 1779–1795.
increasing dietary fiber level. The morphological change              Hesselman, K., and P. Åman. 1986. The effect of β-glucanase on the
                                                                         utilization of starch and nitrogen by broiler chickens fed barley of
in the cecum was dependent on the amount of fiber in                     low or high-viscosity. Anim. Feed Sci. Technol. 15:83–93.
the diet rather than the source. Similarly, changes of                Hetland, H., M. Choct, and B. Svihus. 2004. Role of insoluble non-
intestinal morphology also appeared to be independent                    starch polysaccharides in poultry nutrition. World’s Poult. Sci.
of the types of fiber in rats fed water-soluble extract                  J. 60:415–422.
                                                                      Hetland, H., and B. Svihus. 2001. Effect of oat hulls on performance,
of chicory and other NSP diets (Meehye, 2002). How-                      gut capacity and feed passage time in broiler chickens. Br. Poult.
ever, as suggested by Kalmendal et al. (2011), it can-                   Sci. 42:354–361.
not be ruled out that the thinner mucosal layer of the                Ivarsson, E., B. E. Frankow-Lindberg, H. K. Andersson, and J. E.
broiler intestine is a result of distension because of the               Lindberg. 2011. Growth performance, digestibility and faecal
                                                                         coliform bacteria in weaned piglets fed a cereal-based diet includ-
increased bulk-forming capacities of insoluble fiber.                    ing either chicory (Cichorium intybus L) or ribwort (Plantago
   In conclusion, the present study indicates that chic-                 lanceolata L) forage. Animal 5:558–564.
ory forage has potential to be used as a valuable fiber               Jamroz, D., K. Jakobsen, K. E. Bach Knudsen, A. Wiliczkiewicz,
source for broiler chickens. It appears to be palatable                  and J. Orda. 2002. Digestibility and energy value of non-starch
                                                                         polysaccharides in young chickens, ducks, and geese fed diets
and can be included at 60 g/kg without any major                         containing high amounts of barley. Comp. Biochem. Physiol.
negative effects on diet digestibility and growth per-                   131:657–668.
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