Effects of level and source of oregano leaf in starter diets for broiler chicks

Abstract

This study was carried out to evaluate the effects of different levels and sources of oregano leaf in starter diets for broilers. The 10 different dietary treatments included 1) a nonsupplemented corn-soybean meal diet (negative control); 2) the basal diet + 55 mg/kg of penicillin (positive control); 3 to 6) 2.5, 5.0, 10.0, and 20.0 g of oregano of Mexican origin/kg of diet; and 7 to 10) 2.5, 5.0, 10.0, and 20.0 g of oregano of Mediterranean origin/kg of diet, respectively. Each diet was fed to 6 replicate pens of 5 male birds in battery brooders for 18 d. Broiler chicks fed diets containing penicillin had higher BW at 18 d and improved FE from 1 to 18 d of age compared with those fed the negative control diet or those fed different levels of oregano leaf of both origins. In addition, different levels of oregano leaf had no effects on BW, FCR, or mortality rate. Birds fed the diet with 20.0 g/kg of oregano of Mediterranean origin were intermediate in feed conversion to birds fed the negative and positive control diets. Higher levels of oregano than used in this study in a more challenging rearing environment may be needed to elicit a stronger positive response to oregano leaf in broiler diets.

Full text

© 2010 Poultry Science Association, Inc.
2010 J. Appl. Poult. Res. 19 :137–145
doi: 10.3382/japr.2009-00088
Effects of level and source of oregano leaf
in starter diets for broiler chicks
1
A. Karimi ,*† F. Yan ,* C. Coto ,* J. H. Park ,* Y. Min ,* C. Lu ,* J. A. Gidden ,‡
J. O. Lay Jr. ,‡ and P. W. Waldroup *2
* Poultry Science Department, University of Arkansas, Fayetteville 72701;
† Animal Science Department, University of Kurdistan, Sanandaj, Kurdistan, Iran; and
‡ Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville 72701
Primary Audience: Nutritionists, Feed Additive Companies, Veterinarians, Researchers,
Production Managers
SUMMARY
This study was carried out to evaluate the effects of different levels and sources of oregano
leaf in starter diets for broilers. The 10 different dietary treatments included 1) a nonsupple-
mented corn-soybean meal diet (negative control); 2) the basal diet + 55 mg/kg of penicillin
(positive control); 3 to 6) 2.5, 5.0, 10.0, and 20.0 g of oregano of Mexican origin/kg of diet; and
7 to 10) 2.5, 5.0, 10.0, and 20.0 g of oregano of Mediterranean origin/kg of diet, respectively.
Each diet was fed to 6 replicate pens of 5 male birds in battery brooders for 18 d. Broiler chicks
fed diets containing penicillin had higher BW at 18 d and improved FE from 1 to 18 d of age
compared with those fed the negative control diet or those fed different levels of oregano leaf of
both origins. In addition, different levels of oregano leaf had no effects on BW, FCR, or mortal-
ity rate. Birds fed the diet with 20.0 g/kg of oregano of Mediterranean origin were intermediate
in feed conversion to birds fed the negative and positive control diets. Higher levels of oregano
than used in this study in a more challenging rearing environment may be needed to elicit a
stronger positive response to oregano leaf in broiler diets.
Key words: broiler chick , oregano , Mediterranean , Mexican , feed conversion ratio
DESCRIPTION OF PROBLEM
It has been well established that antibiotics
have a valuable role in poultry production as
growth-promoting agents and in disease con-
trol. However, because of increasing concern
regarding antibiotic-resistant bacteria, their use
in animal and poultry feed has been banned in
several countries and is under significant public
scrutiny in other countries. Consequently, the
poultry industry may be adversely affected by
disease challenge and loss of production as a re-
sult of those restrictions. The European ban on
antibiotic use in animal and poultry nutrition has
1 Published with approval of the director, Arkansas Agricultural Experiment Station (Fayetteville). Mention of a trade name,
proprietary product, or specific equipment does not constitute a guarantee or warranty by the University of Arkansas and does
not imply its approval to the exclusion of other products that may be suitable.
2 Corresponding author: Waldroup@uark.edu
by guest on October 29, 2015http://japr.oxfordjournals.org/Downloaded from

increased infection and the use of therapeutic
antibiotics; however, it has resulted in an overall
decrease in antibiotic use in animal and poultry
production [1].
Several types of herbal products and their oil
extracts have enhanced broiler performance and
resulted in growth-promoting effects. These may
serve as environmental friendly alternatives to
the antibiotic growth promoters commonly used
in animal and poultry feed. The proposed mode
of action of herbal products is attributed to their
antimicrobial properties [2–7], oxidative-resis-
tant activity [8–10], enhancement of the immune
system [11], and, consequently, improvement in
poultry performance.
Oregano (Origanum vulgare L.) is a species
of Origanum, an aromatic herbal product, which,
because of its highly potent chemical nature, has
been used as a functional herbal product, mainly
for preserving food quality, for inhibiting micro-
bial proliferation on ready-to-cook poultry meat,
and, more recently, as an alternative growth pro-
moter in swine and poultry nutrition [12–16].
Carvacrol, thymol, γ-terpinene, and ρ-cymene
are the most important components of oregano
essential oil involved in the functional proper-
ties of oregano [4, 6].
Based on several studies conducted to inves-
tigate the influence of oregano products (oil ex-
tract or its dried leaf) on broiler performance,
researchers have concluded that oregano has the
potential to promote broiler performance [3, 12,
13, 16] and reduce bacterial inhabitants of the
gastrointestinal tract such as Clostridium per-
fringens and Escherichia coli [5, 7]. However,
prediction of the broiler response to oregano and
other herbal supplements is not straightforward;
it is highly influenced by herbal variety [17–22],
level of supplementation [5, 23–26], environ-
mental and sanitary conditions (challenged vs.
unchallenged), nutrient composition of the diet
[17, 27, 28], and the possible interaction with
other additives such as organic acids [29].
Because the effects of different levels of
oregano from different geographical regions
have not been studied, the objective of the pres-
ent study was to investigate the effects of dif-
ferent levels of dried oregano leaf of 2 origins
(Mediterranean vs. Mexican) on broiler chick
performance during the starter period.
MATERIALS AND METHODS
This experiment was conducted to evaluate
the effects of different levels of dried oregano
leaf from 2 origins. Both oregano samples were
provided by a local company [30] that provides
breading mixes for the poultry industry. The
relative percentage of several volatile essential
oil contents of both dried leaf oregano samples
(Mediterranean vs. Mexican) were determined
by gas chromatography (GC)-mass spectrom-
etry (MS) with headspace analysis. The analysis
used a CombiPal (CTC Analytics) autosampler
interfaced with a Varian 450 gas chromatograph
and a Varian 320 triple quadruple MS system
[31]. For the headspace measurement, the sam-
ple was heated to 60°C for 5 min and 0.5 mL
of the headspace was collected. The GC separa-
tion was conducted using a 30M Varian Factor 4
VF-5ms capillary column [31]. The temperature
program was 40°C for 1 min, followed by a lin-
ear temperature program increasing to 250°C at
10°C/min, followed by a 3-min hold. The split
ratio on the column was 20:1. Mass spectrom-
etry analysis was by electron ionization-MS us-
ing the system in the MS-only mode [31, 32].
Identification of components was based on an
automated comparison of experimental spectra
with spectra contained in the National Institute
of Standards and Technology NIST05 mass
spectral database and on subsequent visual con-
firmation by the instrument operator [33]. The
relative distribution of components in the head-
space was determined using the integrated areas
for each of the GC components resolved in the
total ion chromatogram, using the standard Var-
ian Workstation software [31]. The percentage
of each component was based on the peak area
divided by the sum of the peak areas for all com-
ponents.
Experimental Diets
A corn-soybean meal basal diet was formu-
lated to meet the nutrient levels suggested by a
major poultry breeder [34]. The basal diet was
formulated on a digestible amino acid basis us-
ing the suggested amino acid digestion coeffi-
cients [35], with total amino acid levels for the
major ingredients based on published values
[36], adjusted for the CP and moisture content
JAPR: Research Report
138
by guest on October 29, 2015http://japr.oxfordjournals.org/Downloaded from

of the ingredients used in the study. Composi-
tion and calculated nutrient content of the basal
diet is shown in Table 2. The basal diet was
supplemented with complete vitamin and trace
mineral premixes obtained from commercial in-
tegrators.
Dietary Treatments
During this study, 10 dietary treatments were
compared. One treatment (negative control) con-
sisted of the unsupplemented diet and one treat-
ment (positive control) consisted of an antibiotic
product, penicillin (55 mg/kg) [37]. Eight addi-
tional treatments were based on the use of differ-
ent levels of 2 different sources of dried oregano
(Mediterranean vs. Mexican origin), each fed at
2.5, 5.0, 10.0, or 20.0 g/kg of diet. All additives
were preblended with a portion of the basal diet
before being added to the final mix. Each diet
was fed in mash form to 6 replicate pens of 5
male chicks of a commercial broiler strain. Test
diets and tap water were provided for ad libitum
consumption from the day of hatch to 18 d of
age.
Chicks and Housing
Three hundred sexed 1-d-old male chicks of
a commercial meat-type strain (Cobb 500) [38]
were obtained from a local hatchery, where they
had been vaccinated in ovo for Marek’s disease
and had received vaccinations for Newcastle
disease and infectious bronchitis posthatch via
a coarse spray. Five birds were randomly as-
signed to each of 60 compartments in electri-
cally heated battery brooders with raised wire
floors, maintained in a temperature-controlled
room. A 24-h lighting program was provided.
The experimental procedures used in this trial
were approved by the University of Arkansas In-
stitutional Animal Care and Use Committee and
were in compliance with recommended guide-
lines [39].
Measurements
Birds were weighed as a group on arrival
and at 18 d of age. Feed intake was recorded at
the same time points for determination of FCR.
Chicks were checked twice daily for mortality,
with BW of dead birds used to adjust FCR.
Statistical Analysis
Data were analyzed according to the GLM
procedure of SAS [40] as a completely random-
ized design experiment. Significant differences
among treatments were accepted at P ≤ 0.05 and
means were separated using Duncan’s new mul-
tiple range test.
RESULTS AND DISCUSSION
Oregano Essential Oil Content
The relative chemical composition of both
samples of dried oregano leaf is shown in Table
1, with the major constituents carvacrol, O-cy-
mene, γ-terpine, and β-terpineol in the Medi-
terranean sample, and carvacrol, O-cymene,
thymol, and eucalyptol in the Mexican sample.
Both oregano samples used in this study were
rich in essential oils, with both having the ex-
pected high levels of carvacrol and O-cymene
characteristic of oregano. However, the relative
concentrations and overall composition were
different between the 2 oregano samples. Varia-
tions in the chemical composition of essential
oils of herbal products are predictable, which is
mainly related to the geographical origin or their
botanical characteristics, and these have been
reported by other researchers [41, 42].
Performance of Broiler Chicks
The results of the present experiment on the
comparative effects of different levels of dried
oregano leaf of 2 origins compared with the con-
trol (negative) and penicillin (positive control)
treatments are summarized in Table 3.
Effects of Penicillin
Broiler chicks fed a diet containing 55 mg/
kg of penicillin had significantly higher BW at
18 d of age compared with the negative control
and with all the oregano treatments. The broiler
chicks fed penicillin had significantly improved
FCR compared with birds fed the negative con-
trol diets and with birds fed all oregano diets ex-
cept those fed 20.0 g/kg of oregano of Mediter-
ranean origin. Mortality rate was not affected by
dietary treatment. Based on these results, the use
of an antibiotic growth promoter such as peni-
cillin was confirmed as effective in improving
KARIMI ET AL.: OREGANO IN BROILER DIETS 139
by guest on October 29, 2015http://japr.oxfordjournals.org/Downloaded from

broiler BW and feed conversion. Antimicrobial
growth-promoting agents mainly have been used
in broiler diets to decrease or control the detri-
mental effects of undesirable microorganisms.
The mode of action and the growth-promotion
potential of antibiotics have been fully discussed
in several recent reviews [43–49].
Oregano Compared with the Control
The supplementation of broiler diets with
dried oregano leaf had no significant effect on
BW of broiler chicks at 18 d of age compared
with birds fed the control diet. In addition, the
origin of the dried oregano leaf (Mexican vs.
Mediterranean) or the levels of supplementation
(2.5, 5.0, 10.0, or 20.0 g/kg of basal diet) had no
significant effect on broiler BW. Supplementa-
tion of different oregano levels and sources had
no effects on FCR.
Oreganum vulgare L. is the most variable
species of Origanum and the only one common-
ly known as oregano in most European coun-
tries. Oregano is mainly native to Europe, the
JAPR: Research Report
140
Table 1. Relative concentration (%) of volatile essential oils from dried oregano leaf of Mediterranean and Mexican
origin as identified by headspace gas chromatography-mass spectrometry analysis
Entry no.
Retention time,
min Compound
Area percentage, %
Ratio,
Mediterranean:MexicanMediterranean Mexican
1 6.27 α-Thujene 1.20 <0.20
2 6.42 α-Pinene 4.38 0.80 5.2
3 6.71 Camphene 0.97 1.00 1.0
4 7.06 β-Sabinene 1.75 <0.20
5 7.17 β-Pinene 1.05 0.40 2.9
6 7.27 β-Myrcene 2.26 1.20 2.0
7 7.65 3-Carene 1.32 0.50 2.7
8 7.77 α-Terpinene 1.06 0.30 3.4
9 7.91 O-Cymene 16.75 19.40 0.9
10 7.98 Unknown 2.32 1.30 1.8
11 8.02 Unknown 0.80 <0.20
12 8.06 Eucalyptol 6.03 11.80 0.5
13 8.44 γ-Terpine 11.57 0.40 26.4
14 8.64 β-Terpinol 1.89 0.60 3.2
15 8.88 Unknown 0.48 0.20 2.2
16 8.98 Fenchone 0.28 3.20 0.1
17 9.05 Linalool 2.30 <0.20
18 9.15 β-Terpineol 9.12 0.40 20.8
19 9.24 Thujone 0.14 <0.20
20 9.51 Terpineol isomer 0.31 <0.20
21 9.78 Terpineol isomer 0.14 <0.20
22 9.92 Camphor 0.43 <0.20
23 10.28 Borneol 1.36 0.90 1.5
24 10.38 1-Terpen-4-ol 2.34 2.70 0.9
25 10.59 α-Terpineol 1.01 1.50 0.7
26 11.02 Methyl thymyl ether 0.34 0.50 0.7
27 11.16 Isothymol methyl ether 0.71 <0.20
28 11.26 Lanalyl anthranilate 1.84 <0.20
29 11.37 Thymoquinone 0.20 <0.20
30 11.80 Thymol isomer <0.2 0.40
31 11.88 Thymol 2.00 12.30 0.2
32 12.04 Carvacrol 19.54 29.80 0.7
33 13.78 Caryophyllene 2.19 4.80 0.5
34 13.90 α-Bergamotene <0.2 0.70
35 14.02 Unknown 0.13 0.40 0.3
36 14.24 α-Caryophyllene 0.12 2.70 0.0
37 14.78 Bisabolene 0.47 0.50 1.0
38 15.84 Caryophyllene oxide 0.21 0.40 0.5
by guest on October 29, 2015http://japr.oxfordjournals.org/Downloaded from

Mediterranean, and southern and central Asia.
The aromatic, slightly bitter taste and functional
properties of oregano are related to the amount
and composition of its phenolic components.
Carvacrol, thymol, γ-terpinene, and ρ-cymene
are the 4 main components present in oregano
plants [4], and it has been shown that mixing
carvacrol and thymol in the proper amounts may
exert the total antimicrobial inhibition that is ev-
ident with oregano essential oils. This is due to
damage of membrane integrity and to changing
the pH homeostasis and equilibrium of organic
ions [2, 4, 6]. The composition of essential oils
of a particular oregano product can differ be-
tween harvesting seasons or geographical loca-
tions. D’Antuono et al. [50], in a study on native
populations of O. vulgare L. in northern Italy,
showed that great variability exists between the
oil extract (5 to 50 mg/g) and oil composition
(the carvacrol-thymol, biosynthetic pathway,
high linaleol content, the presence of abundant
sesquiterpenes). Dunford and Vazquez [51], in
a study on Mexican oregano (Lippia berlandieri
Schauer), reported that the crop yield and its oil
content were influenced by crop age and orega-
no oil from younger plants containing more total
thymol and carvacrol contents than the mature
plants.
The results of the experiments that have been
carried out to evaluate the response of broiler
chicks to natural additives such as oregano are
inconclusive. Whereas some have reported the
full or partial effectiveness of oregano products
in improving broiler performance [12, 13, 15,
16, 52], others have reported no significant im-
provement [7, 8]. Halle [12] showed that broiler
chicks fed an herbal mixture or 2 different es-
sential oils (oregano-clove or oregano-cinna-
mon) had lower feed intake and improved feed
conversion efficiency; BW was not affected by
the different treatments. Modeva and Profirov
[13] reported that the addition of 0.025 or 0.05%
of a commercial herbal extract containing 5%
essential oil of oregano improved BW gain, in-
creased the activity of enzymes involved in pro-
tein metabolism, and decreased alkaline phos-
phatase activity. Zhang et al. [52] showed that
feeding 2 different commercial mixes of herbal
oil extracts including oregano had no signifi-
cant positive effects on BW, feed consumption,
mortality, or carcass yield, but slightly improved
FCR at 14 d of age. They also reported that feed-
ing higher levels of essential oil mix in a mash-
based diet significantly decreased feed intake
and improved FCR. Çabuk et al. [15] showed
that feeding different levels of herbal oil ex-
KARIMI ET AL.: OREGANO IN BROILER DIETS 141
Table 2. Composition and calculated nutrient content
of basal diet
Item Amount, g/kg
Ingredient
Yellow corn 565.16
Poultry oil 9.05
Soybean meal 388.86
Ground limestone 2.15
Defluorinated phosphate 20.12
Sodium chloride 3.09
Sodium bicarbonate 0.40
MHA-8413.13
l-Threonine 0.35
l-Lysine HCl 1.69
Vitamin premix25.00
Mintrex P_Se31.00
Total 1,000.00
Calculated nutrient
CP % 22.06
Ca % 1.00
Total P % 0.82
Available P % 0.50
Dietary electrolyte balance, mEq/kg 271.22
ME, kcal/kg 2,975.00
Na, % 0.25
Chloride, % 0.25
Digestible Met, % 0.55
Digestible Lys,4 % 1.18
Digestible Trp, % 0.23
Digestible Thr,4 % 0.75
Digestible Ile, % 0.83
Digestible Val,4 % 0.90
Digestible Arg, % 1.34
Digestible TSAA,4 % 0.84
1MHA-84 is a supplemental methionine product [55], and
contains 84% methionine activity.
2Provides per kilogram of diet: vitamin A (from vitamin
A acetate), 7,715 IU; cholecalciferol, 5,511 IU; vitamin E
(from d l -α-tocopheryl acetate), 16.53 IU; vitamin B12, 0.013
mg; riboflavin, 6.6 mg; niacin, 39 mg; pantothenic acid, 10
mg; menadione (from menadione dimethylpyrimidinol), 1.5
mg; folic acid, 0.9 mg; choline, 1,000 mg; thiamine (from
thiamine mononitrate), 1.54 mg; pyridoxine (from pyridox-
ine hydrochloride), 2.76 mg; d-biotin, 0.066 mg; ethoxy-
quin, 125 mg.
3Provides per kilogram of diet: Mn (as manganese methi-
onine hydroxy analog complex), 40 mg; Zn (as zinc methi-
onine hydroxy analog complex), 40 mg; Cu (as copper me-
thionine hydroxy analog complex), 20 mg; Se (as selenium
yeast), 0.3 mg.
4Amino acid values are at NRC minimum recommended
levels.
by guest on October 29, 2015http://japr.oxfordjournals.org/Downloaded from

tract including oregano and several other herbal
products had no significant effects on BW and
gastrointestinal relative weight; however, feed
intake and mortality rate were decreased and
the FCR was significantly improved, especially
in broilers from younger compared with older
breeders. LiHua et al. [16] reported that feed-
ing 75, 100, 125, and 150 mg/kg of oregano oil
extract significantly improved ADG, feed con-
version efficiency, and average breast and leg
muscle percentages, and decreased abdominal
fat percentage in broilers. They reported that 100
mg/kg of oregano oil was the optimal level for
broiler performance. Although the effectiveness
of oregano oil extract in broiler performance has
been demonstrated in some studies, in other stud-
ies, supplementation of broiler diets with orega-
no oil had no significant effects on performance
[7, 8]. Basmacioğlu et al. [8] showed that feed-
ing oregano and rosemary oil individually or in
combination had no significant effects on broiler
performance and mortality. Fukayama et al. [7]
reported that different levels of oregano extract
had no significant effect on broiler performance.
Barreto et al. [53], also in a comparative study
of different herbal products including oregano
extract, showed that neither herbal product had
significant effects on broiler performance, gas-
trointestinal morphology, or AME.
Most studies conducted to evaluate the effec-
tiveness of natural herbal products have mainly
used their oil extracts; however, several studies
have been conducted on the effects of the dried
leaf product as a more direct and less expensive
route of herbal application in practical condi-
tions [9, 10, 21]. Halle et al. [21] showed that
supplementation of diets for male broiler chicks
with graded levels of oregano herb (0, 2, 4, 10,
and 20 g/kg) significantly decreased feed intake
and BW and improved FE. Giannenas et al. [9]
JAPR: Research Report
142
Table 3. Effects of dietary treatments on live performance of male broilers
Item 18-d BW, g 0- to 18-d FCR 0- to 18-d mortality, %
Negative control 570.0b1.400a0.00
Penicillin 55 mg/kg 666.8a1.274b3.33
Mexican oregano, g/kg
2.5 600.8b1.385a3.33
5.0 584.7b1.369a0.00
10.0 596.0b1.408a0.00
20.0 571.2b1.409a0.00
Mediterranean oregano, g/kg
2.5 572.5b1.405a0.00
5.0 590.0b1.379a0.00
10.0 581.3b1.377a0.00
20.0 585.8b1.335ab 0.00
P-value <0.001 0.01 0.54
SEM 11.2 0.030 1.49
Oregano level, g/kg
0.0 570.0 1.400 0.00
2.5 586.6 1.395 1.67
5.0 587.3 1.374 0.00
10.0 588.7 1.393 0.00
20.0 579.0 1.372 0.00
Oregano source
Mexican 584.5 1.394 0.67
Mediterranean 580.1 1.379 0.00
P-value
Oregano level 0.38 0.77 0.41
Oregano source 0.52 0.37 0.32
Source × level 0.29 0.44 0.41
SEM 11.46 0.03 1.05
a,bMeans in a column with a common superscript do not differ significantly (P ≤ 0.05).
by guest on October 29, 2015http://japr.oxfordjournals.org/Downloaded from

showed that broiler BW, daily BW gain, and
FCR were improved in birds fed dehydrated
oregano plant (5 g/kg) as a single supplement
or in combination with α-tocopheryl acetate;
however, the effects of oregano at 5.0 and 7.5
g/kg were higher than those at 2.5 and 10.0 g/
kg of the diet. Bampidis et al. [14] reported that
feeding different levels (0.0, 1.25, 2.5, and 3.75
g/kg) of dried oregano leaf (O. vulgare ssp. hir-
tum) had no significant effect on turkey perfor-
mance up to 43 d; however, feeding a higher
level of oregano after 43 d of age decreased
feed intake and relative weights of the gizzard
and small intestine, and increased feed conver-
sion efficiency, but had no significant effects on
BW, carcass weight, carcass yield, and relative
weights of the heart and liver. Florou-Paneri et
al. [10] reported that broiler chicks fed oregano
had higher performance than birds fed the con-
trol treatment at 42 d of age. Cross et al. [54], in
a study on the effects of herb and oil extracts of
different herbal products (thyme, oregano, mar-
joram, rosemary, or yarrow) showed that dietary
thyme oil or yarrow herb had the greatest influ-
ence on chick performance. They also showed
that the form of feeding of some herbal prod-
ucts (herb vs. oil) had different effects on broiler
performance. Birds fed yarrow herb compared
with its oil extract had greater BW and BW gain,
whereas birds fed thymol oil had greater BW and
BW gain than did those fed the herb [54].
CONCLUSIONS AND APPLICATIONS
1. The origin of the dried oregano leaf
(Mexican vs. Mediterranean) or the lev-
els of supplementation (2.5, 5.0, 10.0, or
20.0 g/kg of basal diet) had no differen-
tial effects on broiler BW and FCR.
2. The antibacterial growth promoter peni-
cillin was effective in improving BW and
feed conversion in broiler starter diets.
3. A high level of dried oregano leaf (20.0
g/kg) of Mediterranean origin resulted in
FCR intermediate to the positive (peni-
cillin) and negative control-fed birds.
4. More research is needed to determine the
effectiveness of dried oregano leaf, espe-
cially at higher levels and with emphasis
on other criteria, such as its effects on
the gastrointestinal microbiota ecosys-
tem and meat quality under different en-
vironmental challenge conditions, to fur-
ther clarify the extent of effectiveness of
dried oregano leaf in broiler nutrition as
a natural alternative to antibiotic growth
promoters.
REFERENCES AND NOTES
1. Castanon, J. I. R. 2007. History of the use of antibi-
otic as growth promoters in European poultry feeds. Poult.
Sci. 86:2466–2471.
2. Lambert, R. J. W., P. N. Skandamis, P. J. Coote, and
G. J. E. Nychas. 2001. A study of the minimum inhibitory
concentration and mode of action of oregano essential oil,
thymol and carvacrol. J. Appl. Microbiol. 91:453–462.
3. Giannenas, I. A., P. Florou-Panera, M. Papazahari-
adou, E. Christaki, N. A. Botsoglou, and A. B. Spais. 2003.
Effect of dietary supplementation with oregano essential oil
on performance of broilers after experimental infection with
Eimeria tenella. Arch. Anim. Nutr. 57:99–106.
4. Burt, S. 2004. Essential oils: Their antibacterial prop-
erties and potential applications in foods—A review. Int. J.
Food Microbiol. 94:223–253.
5. Giannenas, I. A., P. Florou-Paneri, M. Papazahari-
adou, N. A. Botsoglou, E. Christaki, and A. B. Spais. 2004.
Effect of diet supplementation with ground oregano on
performance of broiler chickens challenged with Eimeria
tenella. Arch. Geflugelkd. 68:247–252.
6. Lee, K. W., H. Everts, and A. C. Beynen. 2004. Essen-
tial oils in broiler nutrition. Int. J. Poult. Sci. 3:738–752.
7. Fukayama, E. H., A. G. Bertechini, A. Geraldo, R. K.
Kato, and L. D. S. Murgas. 2005. Oregano extract as an ad-
ditive in the broiler diet. R. Bras. Zootec. 34:2316–2326.
8. Basmacioğlu, H., Ö. Tokuşoğlu, and M. Ergül.
2004. The effect of oregano and rosemary essential oils or
α-tocopheryl acetate on performance and lipid oxidation of
meat enriched with n-3 PUFAs in broilers. S. Afr. J. Anim.
Sci. 34:197–210.
9. Giannenas, I. A., P. Florou-Paneri, N. A. Botsoglou,
E. Christaki, and A. B. Spais. 2005. Effect of supplementing
feed with oregano and/or α-tocopheryl acetate on growth of
broiler chickens and oxidative stability of meat. J. Anim.
Feed Sci. 14:521–535.
10. Florou-Paneri, P., I. Giannenas, E. Christaki, A. Go-
varis, and N. Botsoglou. 2006. Performance of chickens and
oxidative stability of the produced meat as affected by feed
supplementation with oregano, vitamin C, vitamin E and
their combinations. Arch. Geflugelkd. 70:232–240.
11. Dorhoi, A., V. Dobrean, M. Zahan, and P. Virag.
2006. Modulatory effects of several herbal extracts on avian
peripheral blood cell immune responses. Phytother. Res.
20:352–358.
12. Halle, I. 2001. Effects of essential oils and herbal
mixtures on growth of broiler chicks. Pages 439–442 in
Proc. Symp. Vitamine und Zusatzstoffe in der Ernährung
von Mensch und Tier, Jena, Thüringen, Germany. Inst.
Ernähr. Biol. Pharm. Fak, Friedrich-Schiller-Univ., Jena,
Germany.
13. Modeva, T., and Y. Profirov. 2003. Influence of the
oregano etheric oil on weight gain and some blood biochem-
ical indices in chickens. Zhivotn. Nauki 40:59–62.
KARIMI ET AL.: OREGANO IN BROILER DIETS 143
by guest on October 29, 2015http://japr.oxfordjournals.org/Downloaded from

14. Bampidis, V. A., V. Christodoulou, P. Florou-Pan-
eri, E. Christaki, P. S. Chatzopoulou, T. Tsiligianni, and
A. B. Spais. 2005. Effect of dietary dried oregano leaves
on growth performance, carcase characteristics and serum
cholesterol of female early maturing turkeys. Br. Poult. Sci.
46:595–601.
15. Çabuk, M., M. Bozkurt, A. Alçiçek, Y. Akbaş, and K.
Küçükyilmaz. 2006. Effect of an herbal essential oil mixture
on growth and internal organ weight of broilers from young
and old breeder flocks. S. Afr. J. Anim. Sci. 36:135–141.
16. LiHua, C., Y. Ying, L. YiFu, and C. Lei. 2007. Effects
of oregano oil on growth performance and carcass quality of
broilers. China Poult. 29:9–11.
17. Fritz, Z., A. Schleicher, S. Kinal, L. Jarosz, and F.
Majdanski. 1992. Substitution of antibiotics by herbs in feed
mixtures for broiler chicks. Rocz. Nauk. Zootech. Monogr.
Rozorawy 11:315–325.
18. Lee, K. W., H. Everts, H. J. Kappert, K. H. Yeom, and
A. C. Beynen. 2003. Dietary carvacrol lowers body weight
gain but improves feed conversion in female broiler chick-
ens. J. Appl. Poult. Res. 12:394–399.
19. Demir, E., S. Sarica, M. A. Özcan, and M. Suicmez.
2003. The use of natural feed additives as alternatives for an
antibiotic growth promoter in broiler diets. Br. Poult. Sci.
44(Suppl.):S44–S45.
20. Hassan, I. I., A. A. Askar, and G. A. El-Shourbagy.
2004. Influence of some medicinal plants on performance:
Physiological and meat quality traits of broiler chicks.
Egypt. Poult. Sci. J. 24:247–266.
21. Halle, I., R. Thomann, U. Bauermann, M. Henning,
and P. Köhler. 2004. Effects of a graded supplementation of
herbs and essential oils in broiler feed on growth and carcass
traits. Landbauforsch. Völkenrode 54:219–229.
22. Kapica, M., M. Kwiecien, I. Puzio, M. Bienko, R. P.
Radzki, and M. Pawlowska. 2006. Influence of some herbs
on the activity of digestive enzymes in chickens. Med.
Weter. 62:1048–1050.
23. Williams, N., and E. Kienholz. 1974. The effect of
chili, curry and black pepper powders in diets for broiler
chickens. Poult. Sci. 53:2233–2234.
24. Alçiçek, A., M. Bozkurt, and M. Çabuk. 2003. The
effect of an essential oil combination derived from selected
herbs growing wild in Turkey on broiler performance. S.
Afr. J. Anim. Sci. 33:89–94.
25. Alçiçek, A., M. Bozkurt, and M. Çabuk. 2004. The
effect of a mixture of herbal essential oils, an organic acid
or a probiotic on broiler performance. S. Afr. J. Anim. Sci.
34:217–222.
26. Ertas, O. N., T. Güler, M. Çiftçi1, B. Dalkihç1, and Ü.
G. Simsek. 2005. The effect of an essential oil mix derived
from oregano, clove and anise on broiler performance. Int.
J. Poult. Sci. 4:879–884.
27. Fritz, Z., A. Schleicher, S. Kinal, L. Jarosz, and F.
Majdanski. 1991. Application of an herbal medicine replac-
ing antibiotics in mixed feeds for broilers. Page 412 in Proc.
Symp. Vitamine und Weitere Zusatzstoffe bei Mensch und
Tier, Jena, Thüringen, Germany. Inst. Ernähr. Biol. Pharm.
Fak., Friedrich-Schiller-Univ., Jena, Germany.
28. Jamroz, D., A. Wiliczkiewicz, T. Wertelecki, J. Orda,
and J. Skorupińska. 2005. Use of active substances of plant
origin in chicken diets based on maize and locally grown
cereals. Br. Poult. Sci. 46:485–493.
29. El-Hakim, A. S. A., G. Cherian, and M. N. Ali. 2009.
Use of organic acid, herbs and their combination to improve
the utilization of commercial low protein broiler diets. Int.
J. Poult. Sci. 8:14–20.
30. Newlywed Foods, Springdale, AR.
31. Varian Inc., Lake Forest, CA.
32. Daferera, D. J., B. N. Ziogas, and M. G. Polissiou.
2000. GC-MS analysis of essential oils from some Greek
aromatic plants and their fungitoxicity on Penicillium digi-
tatum. J. Agric. Food Chem. 48:2576–2581.
33. National Institute of Standards and Technology. 2005.
NIST/EPA/NIH Mass Spectral Library. Standard Reference
Database 1A. Standard Reference Data Program. Natl. Inst.
Stand. Technol., Gaithersburg MD.
34. Aviagen, Huntsville, AL.
35. Ajinomoto Heartland LLC, Chicago IL.
36. Evonik Degussa Corp., Kennesaw, GA.
37. Penicillin 100, Alpharma Inc., Bridgewater, NJ.
38. Cobb 500, Cobb-Vantress Inc., Siloam Springs, AR.
39. FASS. 1999. Guide for the Care and Use of Agricul-
tural Animals in Agricultural Research and Teaching. 1st
rev. ed. Fed. Anim. Sci. Soc., Savoy IL.
40. SAS Institute. 1991. SAS User’s Guide: Statistics.
Version 6.03 Edition. SAS Inst. Inc., Cary, NC.
41. Bisht, D., C. S. Chanotiya, M. Rana, and M. Semwal.
2009. Variability in essential oil and bioactive chiral monot-
erpenoid compositions of Indian oregano (Origanum vul-
gare L.) populations from northwestern Himalaya and their
chemotaxonomy. Ind. Crops Prod. 30:422–426.
42. Figuérédo, G., P. Cabassu, J. Chalchat, and B. Pas-
quier. 2006. Studies of Mediterranean oregano populations.
VIII—Chemical composition of essential oils of oreganos of
various origins. Flavour Fragr. J. 21:134–139.
43. Donoghue, D. J. 2003. Antibiotic residues in poul-
try tissues and eggs: Human health concerns? Poult. Sci.
82:618–621.
44. Joerger, R. D. 2003. Alternatives to antibiotics: Bac-
teriocins, antimicrobial peptides and bacteriophages. Poult.
Sci. 82:640–647.
45. Jones, F. T., and S. C. Ricke. 2003. Observations on
the history of the development of antimicrobials and their
use in poultry feeds. Poult. Sci. 82:613–617.
46. Dibner, J. J., and J. D. Richards. 2005. Antibiotic
growth promoters in agriculture: History and mode of ac-
tion. Poult. Sci. 84:634–643.
47. Ricke, S. C., M. M. Kundinger, D. R. Miller, and J.
T. Keeton. 2005. Alternatives to antibiotics: Chemical and
physical antimicrobial interventions and foodborne patho-
gen response. Poult. Sci. 84:667–675.
48. Kelly, L., D. L. Smith, E. L. Snary, J. A. Johnson, A.
D. Harris, M. Wooldridge, and J. G. Morris Jr. 2004. Animal
growth promoters: To ban or not to ban? A risk assessment
approach. Int. J. Antimicrob. Agents 24: 7–14.
49. Kilonzo-Nthenge, A., S. N. Nahashon, F. Chen, and
N. Adefope. 2008. Prevalence and antimicrobial resistance
of pathogenic bacteria in chicken and guinea fowl. Poult.
Sci. 87:1841–1848.
50. D’Antuono, L. F., G. C. Galletti, and P. Bocchini.
2000. Variability of essential oil content and composition of
Origanum vulgare L. populations from a north Mediterra-
nean area (Liguria region, northern Italy). Ann. Bot. (Lond.)
86:471–478.
51. Dunford, N. T., and R. S. Vazquez. 2005. Effect of
water stress on plant growth and thymol and carvacrol con-
JAPR: Research Report
144
by guest on October 29, 2015http://japr.oxfordjournals.org/Downloaded from

centrations in Mexican oregano grown under controlled con-
ditions. J. Appl. Hort. 7:20–22.
52. Zhang, K. Y., F. Yan, C. A. Keen, and P. W. Waldroup.
2005. Evaluation of microencapsulated essential oils and or-
ganic acids in diets for broiler chickens. Int. J. Poult. Sci.
4:612–619.
53. Barreto, M. S. R., J. F. M. Menten, A. M. C. Racan-
icci, P. W. Z. Pereira, and P. V. Rizzo. 2008. Plant extracts
used as growth promoters in broilers. Braz. J. Poult. Sci.
10:109–115.
54. Cross, D. E., R. M. McDevitt, K. Hillman, and T.
Acamovic. 2007. The effect of herbs and their associated
essential oils on performance, dietary digestibility and gut
microflora in chickens from 7 to 28 days of age. Br. Poult.
Sci. 48:496–506.
55. Novus International Inc., St. Louis MO.
KARIMI ET AL.: OREGANO IN BROILER DIETS 145
by guest on October 29, 2015http://japr.oxfordjournals.org/Downloaded from