Italian Journal of Animal Science 2013; volume 12:e93

PAPER

Effect of corn particle Introduction Corresponding author: Prof. Marco Bagliacca,

size and inclusion of organic Many Authors have reported on the effect of Dipartimento di Scienze Veterinarie, Università

acid in the diet on growth the form and particle size of poultry feed on
performance parameters (Healy, 1992; Nir et
di Pisa, viale delle Piagge 2, 56100 Pisa, Italy.
Tel. +39.050.2216885 – Fax: +39.050.2210655.
performance and al., 1994ab; Nir et al., 1995; Engberg et al., E-mail: mbagliac@vet.unipi.it
gastrointestinal structure 2002, Amerah et al., 2007b). It is also well
Key words: Broiler performance, Particle size,
in young chicks known that physical properties of feed, such as
proventriculus by-passing organic acids, may
Organic acids, Gut traits.

influence food deterioration, gut development,

Baldassare Fronte,1 Ismail Bayram,2 Acknowledgments: we are grateful to Mr. Biagini
pathogen proliferation and production of toxic and Mr. Rustici of the Bandite di Scarlino, for
Abdil Burhaneddin Akkaya,3
metabolites (Ricke, 2003; Gauthier et al., 2007; hosting the trials in the Public Center for Game
Giacomo Rossi,4 Marco Bagliacca1 Grilli et al., 2007). However, there is still no Production (CPPS) Casolino, Mr. Lorenzo and Mr.
1
Dipartimento di Scienze Veterinarie, information available about the contemporary Paolo, workers of the CPPS Casolino for their
Università di Pisa, Italy use of different particle sizes in the feed and extremely effective collaboration, and VETAGRO
2 SpA, Reggio Emilia, Italy, for providing the organ-
Hayvan Besleme Bölümü, the use of proventriculus by-passing organic
Afyon Kocatepe Üniversitesi, acids. Given this, the aim of the present study ic acids used in the trial.

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was to investigate the effects of different corn The trial was carried out at the Public Center for
Afyonkarahisar, Turkey Game Production, Località Casolino, Scarlino,
particle sizes combined or not with proven-

on
3
Cb-Ideal Tar. Hay. Vet. Ltd. Şti. GR, Italy, and the research was funded by the
Afyonkarahisar, Turkey triculus by-passing organic acids on growth
Province of Grosseto and the University of Pisa.
4 performances and some histological traits of
Dipartimento di Scienze Veterinarie,
the gut of the young broiler chicks during the

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Università di Camerino, Italy Received for publication: 20 May 2013.
starter phase when they are establishing their Revision received: 10 October 2013.
ability to use energy and amino acids from Accepted for publication: 25 October 2013.
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feed. The presence of organic acids in the
small intestine can, in fact, be guaranteed by This work is licensed under a Creative Commons
Abstract Attribution NonCommercial 3.0 License (CC BY-
ia
bacterial degradation of the unabsorbed starch
contained in the coarser particles that remain NC 3.0).
c

The effect of 3 corn particle sizes (dgw: 375, undigested in the upper part of the gut, or can
©Copyright B. Fronte et al., 2013
er

1117, and 2402 µm) combined with or without be added directly to the feed as an organic acid Licensee PAGEPress, Italy
organic acids (0.3 g/kg of Galliacid S®) was blend. Italian Journal of Animal Science 2013; 12:e93
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investigated on broilers from day 1 to day 21; doi:10.4081/ijas.2013.e93

540 1-day old Ross 708 males were raised in 36
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pens (3x2 factorial design, 6 blocks each). We

measured: body weight, feed intake, feed con- Materials and methods Particle Size in Feeedstuffs, 1969) and calcu-
version ratio, liver weight, pH weight and lated as follows:
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height of empty gizzard, pH and length of This study was approved by the Ethical dgw = log–1 [Σ(Wi log di) ΣW–1] and Sgw =
intestine and caeca, height and width of ileal Board of the Universities of Pisa (Italy) and log–1[ΣWi (log di - log dgw)2 ΣW–1]½
on

villi, crypt depth/gland diameter, total bacteria every phase of animal husbandry and slaugh-
count. Different corn particle sizes and organic ter was carried out according to international where
acid supplements only affected feed intake ethical and welfare standards. dgw is geometric mean diameter of the particle
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(days 14 and 21), feed conversion ratio (day A total of 576 1-day-old Ross 708 males were sizes;
14), villus height, and crypt depth. On day 21, randomly allocated to 6 groups and 36 pens Sgw is geometric standard deviation of the par-
fine milling had negative effects on body (0.8×1.2 m) randomised in 6 blocks, 16 birds to ticle sizes;
weights compared with larger feed particle a pen. The experimental mash (i.e. non-crum- di is geometric diameter of particles on the ith
size (816 vs 848 and 844 g); acidic additive had bled) broiler starter diets (Table 1) were for- sieve (=di X di+1]½;
a positive effect on broiler growth (859 vs 813 mulated with the same composition but with Wi is the weight fraction on the ith sieve.
g). Length of small intestinal villi and crypt three different corn particle sizes (fine, medi- All the diets were distributed ad libitum and
depth were affected by both particle size and um and coarse milling) and were combined or met or exceeded NRC recommendations
organic acids (fine to coarse small intestinal not (in a 3×2 factorial design) with a proven- (1994). Each pen was provided with a wood
villi: 1869a, 1401c, and 1039d µm in non-acidi- triculus by-passing organic acid blend shaving floor, heated by liquid propane gas
fied; 1708b, 1535c, and 942e µm in acidified. (Galliacid S®). The mash feed form was used heaters, and submitted to a 24-h artificial
Fine to coarse crypt depth: 102ab, 98b; 65c µm in to increase the effects of different milling lighting regime. Individual live weight and pen
non-acidified; 106a, 70c, and 66c µm in acidi- approaches since the benefits associated with feed intake were measured weekly. At Day 22,
fied). No difference was observed in total bac- crumble or pellet feed form on broiler perform- 4 broilers from 3 pens were randomly selected
teria counts of the gut in relation to the differ- ance are well known (Attia et al., 2012; and slaughtered by cervical dislocation after
ent treatments. Use of organic acids during Engberg et al., 2002; Bjerrum et al., 2005; diazepam injection. The liver and the whole
starter phase is useful, especially when the Huang et al., 2006). The particle sizes of the gastrointestinal structure was removed and
milling process is inappropriate. different feeds were determined by a standard dissected, and the following traits were meas-
set of sieves (Committee on Classification of ured:

[Ital J Anim Sci vol.12:e93, 2013] [page 567]

 Fronte et al.

- liver weight: after opening the abdomen, the ured using a digital pH meter; sectioned at 2-3 µm and stained with
liver was removed and immediately - total bacterial count: approximately 1 g of the haematoxylin and eosin (at least 10 fields
weighed; small intestinal and caecal contents was with 8-10 villi per field and 10 coronal sec-
- filled and empty gizzard weight: the entire mixed with 9 mL of 0.85% NaCl sterile dilu- tions were examined for each chicken);
gut was removed, and the gizzard was care- tion (Bryant and Burkey, 1953), and measurements were performed using an
fully excised and immediately weighed. The homogenised for 3 min in an Omnimixer. image analysis system (Image-Pro Plus;
gizzard was then slit longitudinally, washed Serial dilutions were made in saline and pre- Media Cybernetics, Silver Spring, MD, USA)
to remove food particles, and re-weighed; pared in duplicate on pour plates or in shake on digitalised images (Nikon Optiphot-2).
- gizzard height: the longitudinally slit giz- tubes. The bacterial count comprehensive of Data were analysed as a randomised com-
zard was measured by means of a scanner- evaluation of total aerobes and anaerobe pop- plete block design with 6 treatments in a facto-
based image acquisition. Each half dissec- ulations in the small intestine and caecum, rial arrangement, and main effects (particle
tion of the gizzard was placed with its was performed using pour plates with size and organic acids) and interactions were
frontal surface toward the scanner Tryptone Glucose Extract Agar (TGEA). analysed by ANOVA using the GLM procedure
(Microtek Scanmaker 4, Redondo Beach, Anaerobic counts were established by use of (SAS, 2008). Differences between groups were
CA, USA; 300 dots per inch, auto contrast off either shake culture tubes containing thio- tested for significance by Tukey test. Bacteria
and no active adjustment, black felt covering glycolate medium with added agar (15 g/L) or counts were log transformed before the analy-
the glass below the lid); the anterior and pour plates of the same medium overlaid sis, and weight and length of the organs were

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posterior sections were not used because of with 3% agar (all media were manufactured analysed as absolute values, adding the live
variability in size. The uncompressed TIFF by either Difco or BBL). Incubation was at

on
weights as a covariate in the model (relative
files obtained were analysed using Image 37°C for 48 h for aerobes and for 96 h for values).
Pro Plus® 4.0 (Media Cybernetics, Silver anaerobes. All colonies that developed in the
Spring, MD, USA); shake culture tubes or overlaid agar plates

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- intestine length: the distance from the giz- were recorded as anaerobes, although we
zard to the entry of the caeca was measured realised that some facultative anaerobic bac- Results and discussion
by suspending from the pyloric extremity
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teria were included. Total numbers of bacter-
against a centimetre scale; ial colonies were counted at the end of each
- caeca length: total length of right and left incubation period; Particle size
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caecum were measured from the ileo-caecal - height and width of small intestinal villi and Corn textures used in the different diets are
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junction against a centimetre scale; crypt depth measurements: from each ani- shown in Table 1. The particle sizes, cate-
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- pH of gizzard, small intestine and caeca: mal, a 2 cm section of distal ileum next to gorised in coarse, medium and fine milling,
contents were collected, homogenised with the ileo-caecal valve was fixed overnight in were: 375±1.819 µm, 1117±1.442 µm, and
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a little deionised water, and pH was meas- 70% ethanol, routinely paraffin-embedded, 2402±1.193 µm (dgw±Sgw).
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Table 1. Ingredients, chemical composition and particle sizes of corn in the diets.
Ingredients Calculated analysis
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Maize, g/kg 530.0

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Soybean meal solv. extr. 44, g/kg 335.0 Metabolisable energy, MJ/kg 12.88
Corn gluten, g/kg 50.0 Crude protein, g/kg 224.2
Soybean oil, g/kg 39.0 Fat, g/kg 67.8
N

CaHPO4, g/kg 18.0 Crude fibre, g/kg 51.3

CaCO3, g/kg 16.0 Ash, g/kg g/kg 72.6
Vitamin and mineral premix°, g/kg 5.0 Ca, g/kg 10.0
NaCl, g/kg 2.4 (2.1)§ P total, g/kg 7.6
NaHCO3, g/kg 1.6 Na+, g/kg 1.6 (1.5)
DL-methionine, g/kg 1.5 Cl–, g/kg 1.7 (1.6)
L-lysine HCl, g/kg 1.5
Organic acids - Galliacid S®#, g/kg 0 (0.3)§

Sieve diameter, µ
2830 2000 1180 1000 710 595 425 300 250 90 Residuals
Corn particle sizes^
Fine dgw=375; Sgw=1.819 0.00 0.00 0.00 7.14 10.29 15.81 16.04 13.02 21.21 15.12 1.37
Medium dgw=1117; Sgw=1.442 0.00 6.61 59.00 13.30 11.79 5.19 1.86 0.00 0.00 0.00 2.25
Coarse dgw=2402; Sgw=1.193 31.21 59.59 8.88 0.00 0.15 0.00 0.00 0.00 0.00 0.00 0.17
°Premix supplies (mg/kg diet): vitamin A (retinol), 4.5; vitamin D3 (cholecalciferol), 0.075; vitamin E (dl-alpha-tocopherol), 30; vitamin K3 (menadione), 3; vitamin B1 (thiamin), 2; vitamin B2 (riboflavin), 8;
vitamin B6 (pyridoxine), 5; Vitamin B12 (cyanocobalamin), 0.03; d-biotin, 0.1; vitamin PP (nicotinic acid), 40; vitamin B5 (pantothenic acid), 15; vitamin B9 (folic acid), 1.25; choline chloride, 600; Mn, 150; Zn, 60;
Fe, 35; Co, 0.5; Cu, 10; J, 0.5; Se, 0.1; antioxidant (ethoxyquin), 2.5. #Organic acid composition: fumaric acid 25%, calcium formate + calcium propionate + potassium sorbate 25%, hydrogenated vegetable oil
matrix 50% (microencapsulation). §In brackets the values for the diets containing the organic acids. ^Geometric mean and log normal geometric standard deviation according to Ensor et al., 1969.

[page 568] [Ital J Anim Sci vol.12:e93, 2013]

 Particle size and organic acids in chicks

Growth performances preference for particular particle sizes, signifi- acids) confirmed the results of Nir et al.
Total mortality was 2.25% (min 2-max 3 cant avoidance of finer particles was shown by (1994a) who obtained the best broiler perform-
birds per group). The particle size by organic the decrease in the concentration of the larger ance from Days 7 to 21 of age with diets pre-
acid interaction was not significant for body particles in the feeder over time, either using pared from the medium texture. The reduction
weights. The presence of the organic acids in mash or crumbled diets. Feed intake, in fact, in the negative effects due to the inappropriate
the feed improved the broiler growth starting was significantly lower in the fine-milled feed milling (too fine but also too coarse) obtained
already from Week 1. The negative effect on group both in the medium-milled or coarse- with the presence of the organic acids might
body weight of the chicks fed fine-milled feed milled groups. The significant interaction be explained by a greater palatability induced
started to be evident from the Week 2, but no between particle size and organic acids in the by the presence of the organic acids which
difference was observed between medium and last week was probably due to the reduction in became evident only with apparently unim-
coarse particles (Table 2). the negative effect of fine milling in the group proved milled diets. The suggestions of
Our results on the growth of the broiler con- receiving feed with added organic acids and Gauthier et al. (2007) and Grilli et al. (2007)
firmed the generally negative effects of the the remarkable increase in feed intake in the that dietary supplemental organic acids gener-
fine milling of corn (Parson et al., 2006). The medium group who did not receive organic ally improve the digestibility of proteins, Ca, P,
reduced body weights observed in the chicks acids. This increase in feed intake affected Mg, Zn and also, as a substrate, organic acids
fed the fine-milled feed were probably due the overall performance indices (the same trend enter the intermediary metabolism, are in line
reduced palatability of this feed when it is pre- was shown by Feed Conversion Ratio, FCR). with our results regarding growth performance

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sented in mash form. As already reported by This increase (over 100 g more than that of of chicks.

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Portella et al. (1988), regarding the chicks coarse particle-fed treatment without organic

Table 2. Growth performance in relationship to the particle size of the corn and the presence of the organic acids in the diet.

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Without organic acids lu With organic acids
n Fine Medium Coarse Fine Medium Coarse
Body weight, g
ia
Day 1 576 42 42 41 41 41 41
164b 167ab 167ab 170ab 175a 175a
c

Day 7 572
Day 14 570 402c 407bc 415abc 413abc 424ab 429a
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Day 21 563 782b 830a 828a 849a 866a 861a

Feed intake, g
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Day 1-7 36 165 162 163 168 166 166

Day 7-14 36 383 376 371 396 364 381
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Day 14-21 36 611d 755a 661cd 671bcd 720ab 713abc

Day 1-21 36 1159c 1293a 1195bc 1235abc 1250ab 1261ab
Feed conversion ratio
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Day 1-7 36 1.35 1.30 1.32 1.31 1.25 1.25

Day 7-14 36 1.61 1.59 1.52 1.63 1.48 1.51
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Day 14-21 36 1.64ab 1.85a 1.62b 1.58b 1.64ab 1.69ab

Day 1-21 36 1.58 1.67 1.54 1.55 1.52 1.55
N

Particle size Organic acids SEM F value

of interaction
Fine Medium Coarse No Yes
Body weight, g
Day 1 41 41 41 42 41 0.074 0.091
Day 7 167 171 171 166b 173a 0.189 0.190
Day 14 408b 416ab 422a 408b 422a 0.293 0.169
Day 21 816b 848a 844a 813b 859a 0.407 1.972
Feed intake, g
Day 1-7 166 164 165 164 167 0.455 0.030
Day 7-14 389 370 376 376 380 0.757 1.232
Day 14-21 641c 738a 687b 676b 701a 0.959 7.702**
Day 1-21 1197b 1272a 1228ab 1216b 1248a 1.115 6.469**
Feed conversion ratio
Day 1-7 1.33 1.27 1.28 1.32a 1.27b 0.042 0.229
Day 7-14 1.62 1.53 1.51 1.57 1.54 0.064 0.643
Day 14-21 1.61 1.75 1.65 1.70 1.64 0.062 3.418*
Day 1-21 1.57 1.60 1.55 1.60 1.54 0.050 2.659
a,b,c
Means bearing different letters differ per P<0.05; * P<0.05; ** P<0.01.

[Ital J Anim Sci vol.12:e93, 2013] [page 569]

 Fronte et al.

Carcass traits (Parson et al., 2006; Jensen et al., 1962; Nir et mum, the further increase of a positive factor
Due to the fact that the differences between al., 1994b). Contrary to observations by may not respond like that observed at a lower
blocks were significant, we discarded the worst Engberg et al. (2002) and Huang et al. (2006), level (decreasing instead of increasing the villi
block to minimise bird use without any signif- we did not observe any decrease in pH due to height). For this reason, to be able to under-
icant loss in sensitivity of the experiment increased production of volatile fatty acids stand the phenomenon, when all villi are well
(Festing, 1994). A random selection of 4 birds (VFA) in the digestive tract of any broilers in elongated and defined, the only geometric
from each of the remaining 3 blocks showed relation to the physical properties of the feed. mean diameter and geometric standard devia-
the weights of the slaughtered birds were Also the presence of the organic acids did not tion might be not sufficient to describe the
slightly heavier than the whole reared group, influence the pH of the digestive tract of any of characteristics of the corn particles used in a
but the differences between these were not the broilers, confirming that the antibacterial feed but the papers should report the complete
significant (Table 3). Coarse-milled diets pro- mechanism for organic acid action is not still distribution of the particles between the differ-
duced the highest liver development in the fully understood; activity may vary depending ent sieves. The presence of a particular frac-
chicks (P<0.05). No significant interaction on the physiological status and physicochemi- tion, in fact, could greatly influence the gas-
was found between particle size and organic cal characteristics of the organism but cannot trointestinal structure:
acids, and the organic acids did not influence be explained by pH modulation (Ricke, 2003). - particles <250 (dust-like particles) nega-
liver weight. Since fatty acids are synthesised tively influence the villi height and the gas-
from dietary carbohydrate in liver and then Histological and microbiological trointestinal structure causing ulcerations,

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transported as triglycerides in the plasma to haemorrhages and hardly affect perform-
traits ance;

on
the storage sites, the greater mass of the liver
Independently of the use of organic acids or - particles >1100 µm may be too large for
relates to the better utilisation of carbohy-
different particle sizes, all the villi were elon- chicks to use;
drates that can be obtained with the use of
gated proportionately and were well defined; - particles >0.500 µm (medium and large)
coarse milling. The weight of the gizzard was

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morphology was similar or better defined than may only be useful in a feed to promote cor-
significantly lower in the fine milling group
that reported in the literature (Awad et al., rect development of the intestine, at least till
(3.22% vs 3.41% and 3.53% in medium and
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2009; Nourmohammadi and Afzali, 2013). No day 21 of age (Amerah et al., 2007a, 2007b).
coarse milling). In fact, particles that are too
villi were found atrophied or with pieces scat- On the other hand, the short-chain fatty
fine are not able to sufficiently stimulate giz-
tered in the lumen of the intestine (Nir et al.,
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zard development, so that gizzard function may acids, which promote the proliferative activ-
1994a). Either the two main effects (particle ity in the crypt and villus height, are directly
be reduced due to lower contraction intensities
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and retention times (Amerah et al., 2007a). size and organic acid content) or the interac- produced by bacterial degradation of the
tion (particle size*organic acid content)
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The smaller size of the empty gizzard, reported starch. Starch contained in the coarse parti-
also by Nir et al. (1994ab) and Healy (1992) in affected the villi characteristics in the small cles led to longer residence time within the
intestine. Finer particle sizes enhanced the
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the chicks receiving the fine-milled feed, was gizzard and small gut leading to a more
probably due either to the faster passage of the height of villi (1869 µm without organic acids muscular gizzard; however, more starch
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feed in the gut or to the lower feed consump- and 1708 µm with organic acids) (Table 4). reached, undigested, the intestine. Addition
tion. It is well known that particle size and The same effect was observed in villi width: of short-chain fatty acids, with optimal par-
form of the feed influence the development finer particle size showed larger villi than ticle size, may be sufficient for the optimal
-c

and the physiology of the avian digestive tract every other group (P<0.05). Also crypt depths development of the intestine, and a further
in chicks from Day 7 of age (Nir et al., 1994a; were affected by the particle size and the supplementation can reduce bacterial activ-
on

Nir et al., 1995; Engberg et al., 2002). In our organic acids with the same trend. Villus- ity and villus height. The ratio between vil-
experiment, the reduction in gizzard size was height-to-crypt-depth ratios confirmed the lus-height-to-crypt-depth, however, con-
interactive effect (F4.873**) but showed the firmed the positive effect of coarse particle
N

linked with the reduction in growth, contrary

to observations made by Amerah et al. (2007a) best value for coarse feed without acids (20.5), size and the presence of the organic acids.
who reported that a reduction in particle size followed by fine, medium and coarse feeds In fact, the villus-height:crypt-depth ratio
may not be consistent because gizzard effi- with acids (18.6, 18.9 and 18.4, respectively); are directly correlated with increased
ciency may vary with gizzard size according to the worst were fine and medium feeds without epithelial cell turnover, digestive capacity
gizzard volume. The presence of the organic acids (16.5 and 16.9, respectively). and better performance (Nourmohammadi
acids that bypass the gizzard did not seem to In contrast to reports by other Authors, we and Afzali, 2013).
have any interaction effect on the particle size observed greater villi height when organic In our experiment, analysis of total bacteria
and did not influence gizzard development. No acids were not used and coarser particles were count did not reach the minimum statistical
interaction was observed between pH of the used (Amerah et al., 2007a, 2007b). In this difference; coarse milling of corn and organic
different intestinal tracts and intestine length, study, all the villi and crypt depths were well acid additive did, however, show greater mean
and no difference was found between the main defined suggesting for all of them a good rate counts of total bacteria. Feed acidification with
effects of particle sizes and organic acids. of nutrient absorption and a reduced rate of various short-chain organic acids, such as
However, as expected, the greater caeca devel- enterocyte cell migration from the crypt to the fumaric, propionic, lactic and sorbic, have
opment (measured as length of both tracts) villus (Nourmohammadi and Afzali, 2013; Van been reported to increase nutrient absorption
observed in chicks receiving the fine milled Leeuwen et al., 2004). The trend of the villi and to decrease colonisation of pathogens and
diet without organic acids suggests that the height, crypt depth and their ratio might follow production of toxic metabolites (Jørgensen et
fine ground maize may be retained longer in a parabolic curve with an optimal maximum al., 1999; Kranker et al., 2001; Stege et al.,
the digestive tract of these chicks and, conse- rather than a linear curve with a slope without 2001; Leontides et al., 2003; Huang et al., 2006
quently, there may be a longer digestion phase a maximum so that, after the optimal maxi- Mikkelsen et al. 2004).

[page 570] [Ital J Anim Sci vol.12:e93, 2013]

 Particle size and organic acids in chicks

Table 3. Carcass traits in relationship to the particle size of the corn and the presence of the organic acids in the diet.
Without organic acids With organic acids
n Fine Medium Coarse Fine Medium Coarse
Slaughtering weight, g 71 780c 925ab 892b 920ab 959a 932ab
Liver°, % 71 2.22b 2.45b 2.48ab 2.16b 2.20b 2.51a
Empty gizzard°, % 69 3.36ab 3.45ab 3.52ab 3.08b 3.37ab 3.54a
Gizzard pH 70 2.79 2.91 2.92 2.92 2.92 2.95
Small intestine pH 69 6.66 6.54 6.94 6.52 6.60 6.56
Caeca pH 70 7.03 7.41 7.37 7.11 7.00 7.43
Gizzard high°, cm 72 1.627 1.472 1.449 1.392 1.565 1.500
Intestine length§, mm 71 143.4 148.0 141.1 142.6 146.6 147.9
Caeca length§, mm 69 30.7a 30.2ab 27.5b 28.9ab 29.0ab 28.7ab

Particle size Organic acids SEM F value

of interaction

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Fine Medium Coarse No Yes

on
b b a
Slaughtering weight, g 850 942 912 937 866 0.995 4.255**
Liver°, % 2.2b 2.3b 2.5a 2.3 2.4 0.199 2.903
Empty gizzard°, % 3.22b 3.41a 3.53a 3.44 3.33 0.219 0.416

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Gizzard pH 2.85 2.91 2.93 2.87 2.93 0.084 0.108
Small intestine pH 6.60 6.60 6.75 6.72 6.56 0.123 0.251
Caeca pH 7.07 7.23 7.40 7.27 7.18 0.092 1.261
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Gizzard height°, cm 1.510 1.518 1.475 1.516 1.486 0.052 2.027
Intestine length§, mm 141.4 148.8 144.9 144.1 145.7 0.381 1.158
ia
Caeca length§, mm 29.3 30.1 28.1 29.4 28.8 0.180 2.774
°Relative organ weights reconverted to percentages; SEM reported as original. §Lengths, expressed to parity of slaughter weights. a,b,c
Means bearing different letters differ per P<0.05; *P<0.05; **P<0.01.
c
er
m
om
-c
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Table 4. Histological and microbiological traits of the gut in relation to the particle size of the corn and the presence of organic acids
in the diet.
N

Without organic acids With organic acids

n Fine Medium Coarse Fine Medium Coarse
Villus height, m 211 1869a 1401c 1039d 1708b 1535c 942e
Villus width, m 211 178a 105b 101b 175a 106b 98b
Crypt depth, m 211 102ab 98b 65c 106a 70c 66c
Villus-height-to-crypt-depth ratio 211 16.5b 16.9b 20.5a 18.6ab 18.9ab 18.4ab
Total bacteria°, n 61 1.26×109 1.78×109 3.83×109 9.98×109 2.46×109 2.85×109

Particle size Organic acids SEM F value

of interaction
Fine Medium Coarse No Yes
a b c a
Villus height, µm 1788 1468 991 1436 1395b 0.748 4.964**
Villus width, µm 177a 105b 100b 128 126 0.294 0.073
Crypt depth, µm 104a 84b 66c 88a 81b 0.228 9.371**
Villus-height-to-crypt-depth ratio 17.5b 17.9ab 19.4a 17.9 18.6 0.148 4.873**
Total bacteria°, n 2.24×109 2.09×109 3.30×109 2.05×109 3.03×109 0.147 0.444
a,b,c,d,e
Means bearing different letters differ per P<0.05. °Bacteria counts re-converted to number of colonies in the table. SEM is expressed as log values.

[Ital J Anim Sci vol.12:e93, 2013] [page 571]

 Fronte et al.

more numerous groups of bacteria in the finishing swineherds. Epidemiol. Infect.

Conclusions bovine rumen. J. Dairy Sci. 36:205-217. 131:599-606.
Engberg, R.M., Hedesmann, M.S., Jensen, B.B., Mikkelsen, L.L., Naughton, P.J., Hedemann,
The negative effects observed on the start- 2002. The influence of grinding and pellet- M.S., Jensen, B.B., 2004. Effects of physical
ing growth performances suggest sub-optimal ing of feed on the microbial composition properties of feed on microbial ecology and
chick wellbeing. From this point of view, the and activity in the digestive tract of broiler survival of Salmonella enterica serovar
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