ArticlePDF Available

Dietary Carvacrol Lowers Body Weight Gain but Improves Feed Conversion in Female Broiler Chickens


Abstract and Figures

Dietary thymol, and its isomer, carvacrol, were evaluated as alternatives to antibiotic feed additives in female broiler chickens. In addition, the alleged hypocholesterolemic effect of carvacrol and thymol were tested when the chickens were fed cholesterol-free or cholesterol-containing diets. The experiment had a 2 × 3 factorial arrangement of treatments with diets containing two levels of cholesterol (0 or 1%) and without feed additive or with 200 ppm thymol or carvacrol. Dietary carvacrol lowered feed intake and weight gain but also lowered the feed-to-gain ratio. Dietary thymol, an isomer of carvacrol, did not affect growth performance. Dietary cholesterol significantly increased plasma and liver cholesterol concentrations. Carvacrol lowered plasma triglyceride concentrations but did not affect plasma cholesterol. It is concluded that thymol and its isomer, carvacrol, have different effects on growth performance and triglyceride metabolism in broiler chickens. The two compounds did not have hypocholesterolemic activity, irrespective of whether the diet was cholesterol free or cholesterol rich.
Content may be subject to copyright.
2003 Poultry Science Association, Inc.
Dietary Carvacrol Lowers Body
Weight Gain but Improves Feed
Conversion in Female Broiler
K.-W. Lee,
H. Everts, H. J. Kappert, K.-H. Yeom, and A. C. Beynen
Department of Nutrition, Faculty of Veterinary Medicine, Utrecht University,
P.O. Box 80.152, 3508 TD, Utrecht, The Netherlands
Primary Audience: Nutritionists, Researchers, Veterinarians, Feed Manufacturers
Dietary thymol, and its isomer, carvacrol, were evaluated as alternatives to antibiotic feed
additives in female broiler chickens. In addition, the alleged hypocholesterolemic effect of carvacrol
and thymol were tested when the chickens were fed cholesterol-free or cholesterol-containing diets.
The experiment had a 2 ×3 factorial arrangement of treatments with diets containing two levels
of cholesterol (0 or 1%) and without feed additive or with 200 ppm thymol or carvacrol.
Dietary carvacrol lowered feed intake and weight gain but also lowered the feed-to-gain ratio.
Dietary thymol, an isomer of carvacrol, did not affect growth performance. Dietary cholesterol
significantly increased plasma and liver cholesterol concentrations. Carvacrol lowered plasma
triglyceride concentrations but did not affect plasma cholesterol. It is concluded that thymol and
its isomer, carvacrol, have different effects on growth performance and triglyceride metabolism
in broiler chickens. The two compounds did not have hypocholesterolemic activity, irrespective of
whether the diet was cholesterol free or cholesterol rich.
Key words: essential oil, carvacrol, thymol, broiler, growth performance, lipid metabolism
2003 J. Appl. Poult. Res. 12:394–399
In studies with broilers to identify a possible
supplement alternative to antibiotics, attention is
focused on essential oils and their pure compo-
nents. Essential oils are derived mainly from
spices and herbs and their constituents, which
have antimicrobial effects in vitro [1, 2]. Thymol
(Table 1), a major component of thyme-essential
oils, has been widely studied for its antimicrobial
properties [3, 4]. It can be added to chewing gum
at levels as high as 100 ppm and to nonalcoholic
To whom correspondence should be addressed:
beverages at concentrations of 2.5 to 11 ppm [5].
The reported lethal dose (LD
mg/kg of BW when given orally [6]. Carvacrol
(Table 1), an isomer of thymol, is found in essen-
tial oils isolated from oregano, thyme, marjoram,
and summer savory [7]. Like thymol, carvacrol
also displays antimicrobial activity [3, 8, 9]. Car-
vacrol may be added to baked goods at levels as
high as 120 ppm and to nonalcoholic beverages
at 26 ppm [5]. The LD
of carvacrol in rats is
810 mg/kg of BW when administered by gavage
[6]. The chemical properties and structures of thy-
TABLE 1. Chemical properties and structures of thymol and carvacrol
Thymol Carvacrol
Molecular weight 150 (C
O) 150 (C
Synonym 5-methyl-2-(1-methylethyl)phenol 2-methyl-5-(1-methylethyl)phenol
3066 2245
21CFR 172.515 21CFR 172.515
Occurrence Thyme (lamiaceae, or labiatae) Oregano (lamiaceae, or labiatae)
Appearance White crystals Colorless to pale yellow liquid
Odor Pungent, caustic taste Thymol-like odor
Boiling point, °C 233 237
Density, g/mL 0.969 0.976
The Flavor and Extract Manufacturers Association; code given refers to “generally recognized as safe” (GRAS) status for
their use as food flavor [5].
Food and Drug Administration; code given refers to GRAS status for their use in food [5].
mol and carvacrol are shown in Table 1. The two
compounds have the status of generally recog-
nized as safe (GRAS), which is endorsed by the
Flavor and Extract Manufacturers’ Association
(FEMA) and the Food and Drug Administration
(FDA) of the U.S.A. [5]. Based on in vitro antimi-
crobial studies [3, 4, 8, 9], the minimum inhibitory
concentrations of thymol and carvacrol range
from 100 to 1,000 ppm, yeasts being most sensi-
tive and gram-negative bacteria being resistant.
Given their antimicrobial activity, it would be
expected [10] that thymol and carvacrol could
have positive effects on growth performance in
broilers. The main objective of the present study
was to evaluate the potential of thymol and carva-
crol as growth enhancers in female broilers. It has
been reported that thymol and carvacrol, at dietary
concentrations of 150 ppm, reduce serum choles-
terol in Leghorn chicks [11]. To verify the hypo-
cholesterolemic properties of thymol and carva-
crol, plasma lipid concentrations were also mea-
sured in broilers. To further assess the
hypocholesterolemic action [12] of thymol and
carvacrol, broilers were fed both cholesterol-free
diets, as well as diets with 1% added cholesterol.
The experimental protocol was approved by
the animal experiments committee of the Utrecht
Faculty of Veterinary Medicine.
Animals, Diets, and Experimental Design
Seventy-two 1-d-old female broilers (Cobb)
were purchased from a local hatchery. They were
wing-banded, weighed on arrival, and randomly
allocated to one of six treatments. Each treatment
consisted of two cages with six birds per cage.
Feed and water were provided ad libitum. The
temperature of the facility was 34°C on arrival
of the chickens, was gradually decreased to 25°C
after 3 wk, and then was kept constant. Continu-
ous lighting was used throughout the 4-wk experi-
mental period. The experiment had a 2 ×3 facto-
rial arrangement of treatments with two levels of
dietary cholesterol (0 and 1%) and three treat-
ments with feed additives (none, thymol, and car-
vacrol). The composition of the basal diet is
shown in Table 2. The diet was calculated to
meet the requirement of NRC [13] for essential
amino acids. The basal diet served as the control
diet without cholesterol and additives. Choles-
terol was introduced into the diet at the expense
of an identical amount of corn starch. Thymol
and carvacrol [14] were dissolved in corn oil and
gently mixed with either the cholesterol-free or
cholesterol-rich diets so that the diets contained
5% corn oil and 200 ppm of one of the two
supplements. The cholesterol-free and choles-
terol-rich diets without additives were mixed with
corn oil only. The experimental diets were pre-
pared and supplied on a daily basis.
JAPR: Research Report396
TABLE 2. Composition of the basal (control) diet
Ingredient g/kg
Corn, yellow 300
Corn starch 222
Soybean meal (48% CP) 375
Corn oil 50
Sodium chloride 5
Calcium carbonate 15
Monocalcium phosphate 19
-Methionine 4
Total 1,000
Calculated contents
, kcal/kg 3,171
CP, % 20.8
Lysine, % 1.2
Methionine +cystine, % 1.0
Calcium, % 1.0
Available phosphorus, % 0.5
The 10 g of premix consisted of 24.0 mg of vitamin A
(500,000 IU/g); 6.0 mg of vitamin D
(100,000 IU/g); 60.0
mg of vitamin E (500 IU/g); 6.6 mg of vitamin K
22.7%); 100.0 mg of vitamin B
(purity, 0.1%); 2,000.0
mg of biotin (purity, 0.01%); 1,100.0 mg of choline chloride
(purity, 50%); 1.1 mg of folic acid (purity, 90%); 65.2 mg
of nicotinic acid (purity, 100%); 16.3 mg of d-pantothenate
(purity, 92%); 4.5 mg of vitamin B
(purity, 100%); 12.5
mg of riboflavin (purity, 80%); 2.5 mg of vitamin B1 (purity,
100%); 32.00 mg of CuSO
O; 333.20 mg of FeSO
166.80 mg of MnO; 1.0 mg of Na
O; 220.00 mg
of ZnSO
O; 4.80 mg of CoSO
O; 0.56 mg of KI;
100.00 mg of ethoxyquin, and 5,742.94 mg of corn meal as
The values were calculated from NRC [13].
Body weights were measured weekly. Feed
was weighed daily for each cage, and the leftover
feed was discarded. Daily feed intake was calcu-
lated by dividing the amount of feed consumed
by the number of days and animals. At 28 days
of age, the chickens were killed by cervical dislo-
cation after blood had been collected into heparin-
ized tubes by heart puncture. Plasma was obtained
by centrifugation at 1,700 ×gfor 15 min and
stored at 70°C until analyzed for lipids. Liver
and pancreas were immediately sampled and
weighed. Livers were stored at 70°C, whereas
pancreases were discarded.
Plasma cholesterol [15], triglyceride [16], and
phospholipid concentrations [17] were measured
enzymatically on an autoanalyzer [18]. Plasma,
very-low-density lipoproteins (VLDL), and low-
density lipoproteins (LDL) were precipitated with
phosphotungstic acid/MgCl
according to Ass-
man et al. [19], and the supernatant (high-density
lipoproteins, HDL) was assayed for cholesterol
[15]. Liver total [15] and free [20] cholesterol
that had been extracted [21] were measured enzy-
matically on the autoanalyzer [18]. Liver esteri-
fied cholesterol was calculated as the difference
between total and free cholesterol.
Statistical Analysis
Each pen was considered an experimental
unit. The data were evaluated by two-way AN-
OVA using the program Genstat 4.2 [22], with
feed additives and dietary cholesterol as main
factors. There was no interaction between dietary
cholesterol and feed additives; therefore, the data
are presented as overall means for each factor.
Treatment means were tested for statistically sig-
nificant differences according to the RPAIR pro-
cedures in Genstat Release 4.2 for PC [22]. A
value of P<0.05 was considered significant.
Growth Performance and Organ Weights
Chickens fed carvacrol gained significantly
less weight than those fed thymol, whereas the
controls showed intermediate weight gain (Table
3). Carvacrol versus thymol reduced weight gain
by 4.6%. Feed intake showed a similar pattern:
the carvacrol group ate 5.1 and 6.7% less feed
than the control and thymol group, respectively.
The feed-to-gain ratio was lowest in the carvacrol
group, the decrease being significant when com-
pared with the controls. Dietary cholesterol had
no effect on growth performance (Table 3) while
relative liver weight (g/100 g of BW) was sig-
nificantly increased by cholesterol feeding (P<
0.05). In contrast, the additives had no effect
(Table 3). The color of the livers in chickens fed
cholesterol was yellowish, whereas those of their
counterparts fed the diets without cholesterol
were pinkish. Dietary cholesterol and additives
did not affect pancreas weights (Table 3).
Cholesterol Metabolism
No interaction between cholesterol and addi-
tives was found with regard to plasma and liver
lipids. Cholesterol feeding significantly increased
total plasma cholesterol and triglycerides, but
lowered phospholipids and HDL cholesterol ex-
pressed as a percentage of total plasma cholesterol
TABLE 3. Effect of dietary thymol and carvacrol on growth performance (d 0 to 28) and organ weights (d 28) of
female broiler chickens
Parameters None Carvacrol Thymol SEM
Growth performance
Weight gain, (g/d per bird) 42.4
0.623 42.4 42.3 0.508
Feed intake, (g/d per bird) 58.9
0.832 58.3 58.2 0.679
Feed:gain, (g:g) 1.389
0.010 1.375 1.376 0.008
Organ weights, (g/100 g of live BW)
Liver 2.39 2.32 2.39 0.081 2.14
Pancreas 0.21 0.22 0.21 0.004 0.22 0.21 0.003
Means in the same row within the same main factor not sharing a common superscript are significantly different (P<
Values are expressed as means of four replicates per dietary group.
Values are expressed as means of six replicates per dietary group. A minus sign () means without added cholesterol; a
plus sign (+) means with added cholesterol.
Pooled standard error of mean.
(Table 4). HDL cholesterol was not affected by
cholesterol feeding. Dietary carvacrol signifi-
cantly lowered triglycerides, when compared
with the control and thymol treatments, by an
average of 10.3%. Carvacrol also decreased
plasma phospholipids when compared with the
control treatment. Plasma total and HDL choles-
terol were not changed by the dietary additives.
Cholesterol feeding drastically increased liver
free and esterified cholesterol, but thymol and
carvacrol had no effect (Table 4).
Chickens fed either the diet containing thymol
or the control diet showed no significant differ-
TABLE 4. Effect of dietary thymol and carvacrol on plasma and liver lipids in female broiler chickens at 28 d of
Additive Cholesterol
Parameter None Carvacrol Thymol SEM
Plasma lipids mmol/L mmol/L
Total cholesterol 4.54 4.58 4.62 0.196 3.35
HDL cholesterol 2.36 2.21 2.30 0.056 2.33 2.25 0.045
Triglycerides 1.19
0.030 0.91
Phospholipids 3.11
0.060 3.13
cholesterol, (% of total) 55.9 54.1 54.3 1.343 69.9
Liver cholesterol µmol/g of liver µmol/g of liver
Free cholesterol 23.0 23.8 22.8 0.955 16.0
Esterified cholesterol 56.5 64.0 65.0 11.804 4.0
Means in the same row within the same main factor and treatment group, not sharing a common superscript are significantly
different (P<0.05).
Pooled standard error of mean.
High density lipoprotein.
ence in growth performance. However, dietary
carvacrol at the level of 200 ppm significantly
lowered feed intake and weight gain when com-
pared to thymol. When compared with the control
group, carvacrol feeding significantly lowered the
feed-to-gain ratio. Thus, when comparing thymol
and carvacrol in relation to growth performance,
it appears that carvacrol suppressed feed intake,
leading to lower weight gain in spite of improved
feed conversion. Possibly, carvacrol affected feed
intake by modulating appetite. Deyoe et al. [23]
showed that the flavor of chickens’ diets can stim-
ulate or depress feed intake. The carvacrol effect
on feed-to-gain ratio could relate to increased
efficiency of feed utilization and/or altered car-
JAPR: Research Report398
cass composition, although the latter was not an-
Case et al. [11] reported that dietary carvacrol
and thymol, at 150 ppm, did not influence BW
gain of cockerels with initial weights of 126 g
that were followed during a 21-d feeding trial. In
a previous experiment with female broilers, Lee
et al. [24] also found a lack of effect of thymol
on growth performance and digestive enzyme ac-
tivity when fed at a level of 100 ppm for a period
of 6 wk. It was suggested that the antimicrobial
activity of thymol may be masked by diet compo-
sition and/or environment, in that no effect of
thymol on growth performance was seen when
a well-balanced diet was fed and the birds were
kept in a clean environment, as was done in
this study.
It has been reported that dietary thymol and
carvacrol lower serum cholesterol concentrations
in chickens [11]. The hypocholesterolemic effect
of thymol and carvacrol has been ascribed to
inhibition of 3-hydroxy-3-methylglutaryl coen-
zyme A (HMG-CoA) reductase [25], the rate-
controlling enzyme of the cholesterol synthetic
pathway. The present experiment was designed
to determine if there was an interaction between
dietary cholesterol and either thymol or carvacrol.
It was reasoned that by inhibition of HMG-CoA
reductase activity through cholesterol feeding
[26], there would be no apparent hypocholestero-
lemic effects of thymol and carvacrol. However,
our results failed to reveal a hypocholesterolemic
effect of either thymol or carvacrol, irrespective
of whether the diet was cholesterol free or choles-
1. The results of the present study revealed that dietary carvacrol, but not its isomer, thymol,
lowered feed intake and weight gain but also lowered the feed-to-gain ratio.
2. Dietary carvacrol and thymol did not have hypocholesterolemic activity, irrespective of whether
the diet was cholesterol free or cholesterol rich.
3. Dietary carvacrol, but not thymol, lowered plasma triglycerides.
4. Our observation implies that dietary essential oil components can affect feed utilization or lipid
metabolism. Furthermore, it is likely that essential oils can contain compounds with different
or possibly even opposite effects on growth performance and lipid metabolism.
5. This notion may have impact on the use of essential oils as growth enhancers.
terol rich. As would be expected [27], dietary
cholesterol significantly increased plasma total
cholesterol but did not modulate plasma HDL
cholesterol. The increase in plasma total choles-
terol may have been located in VLDL, as reported
earlier [27, 28], lowering the percentage of total
cholesterol in HDL. Thus, the present study cor-
roborates earlier studies [27, 28] showing that a
substantial portion of plasma total cholesterol in
chickens fed on a cholesterol-free diet is carried in
the form of HDL and that exogenous cholesterol
increases the secretion of VLDL by the liver.
The concentrations of liver free and esterified
cholesterol were not changed either by thymol
and carvacrol. Dietary carvacrol significantly
lowered plasma triglycerides and phospholipids
by 12 and 7%, respectively. According to Yasni
et al. [29], α-curcumene, a component of essential
oils from Curcuma xanthorrhiza, specifically
suppressed hepatic fatty acid synthase. Feeding
of the extracts of Curcuma xanthorrhiza lowered
serum triglycerides without affecting serum cho-
lesterol. On the other hand, d-limonene, an essen-
tial oil component from Citrus sinensis, inhibited
HMG-CoA reductase but did not affect fatty acid
synthetase, which led to a significant reduction
in serum cholesterol [30]. In the light of earlier
studies [29, 30], dietary carvacrol, but not thymol,
may have had more impact on de novo lipogen-
esis than on cholesterol biosynthesis in this study.
An explanation in molecular terms for the obser-
vation that carvacrol lowered plasma triglycerides
should provide further insight in lipid me-
1. Deans, S. G., and G. Ritchie. 1987. Antibacterial properties
of plant essential oils. Int. J. Food Microbiol. 5:165–180.
2. Hammer, K. A., C. F. Carson, and T. V. Riley. 1999. Antimi-
crobial activity of essential oils and other plant extracts. J. Appl.
Microbiol. 86:985–990.
3. Juven, B. J., J. Kanner, F. Schved, and H. Weisslowicz. 1994.
Factors that interact with the antibacterial action of thyme essential
oil and its active constituents. J. Appl. Bacteriol. 76:626–631.
4. Dorman, H. J. D., and S. G. Deans. 2000. Antimicrobial
agents from plants: Antibacterial activity of plant volatile oils. J.
Appl. Microbiol. 88:308–316.
5. Furia, T. E., and N. Bellanca. 1975. Fenaroli’s handbook of
flavor ingredients. Vol. 2. Adapted from the Italian language works
of Prof. Dr. Giovanni Fenaroil. 2nd ed. CRC Press, Cleveland, OH.
6. Jenner, P. M., E. C. Hagan, J. M. Taylor, E. L. Cook, and
O. G. Fitzhugh. 1964. Food flavourings and compounds of related
structure. I. Acute oral toxicity. Food Cosmet. Toxicol. 2:327–343.
7. Guenther, E. 1949. The essential oils. Vol. 2. Van Nostrand,
New York.
8. Didry, N., L. Dubreuil, and M. Pinkas. 1994. Activity of
thymol, carvacrol, cinnamaldehyde and eugenol on oral bacteria.
Pharm. Acta Helv. 69:25–28.
9. Helander, I. M., H-L. Alakomi, K. Latva-Kala, T. Mattila-
Sandholm, I. Pol, E. J. Smid, L. G. M. Gorris, and A. Von Wright.
1998. Characterization of the action of selected essential oil compo-
nents on gram-negative bacteria. J. Agric. Food Chem. 46:3590–
10. Wenk, C. 2000. Recent advances in animal feed additives
such as metabolic modifiers, antimicrobial agents, probiotics, and
enzymes and highly available minerals. Review. Asian-Aus. J. Anim.
Sci. 13:86–95.
11. Case, G. L., L. He, H. Mo, and C. E. Elson. 1995. Induction
of geranyl pyrophosphate pyrophosphatase activity by cholesterol-
suppressive isoprenoids. Lipids 30:357–359.
12. Beynen, A. C., and C. E. West. 1989. Mechanisms underly-
ing nutritional effects on serum cholesterol concentrations. Pages
89–114 in Coronaries and Cholesterol. W. J. Cliff and G. I. Schoefl,
ed. Chapman and Hall Medical, London, United Kingdom.
13. National Research Council. 1994. Nutrient Requirements
of Poultry. 9th rev. ed. Natl. Acad. Press, Washington, DC.
14. Thymol, 99% purity; Acros Organics, Geel, Belgium. Car-
vacrol, 97% purity; Fluka Chemie, Sigma-Aldrich Chemie BV, Zwij-
ndrecht, the Netherlands.
15. Allain, C. C., L. S. Poon, C. G. S. Chen, W. Richmond,
and P. Fu. 1974. Enzymatic determination of total serum cholesterol.
Clin. Chem. 20:476–482.
16. Bucolo, G., and H. David. 1973. Quantitative determination
of serum triglycerides by the use of enzymes. Clin. Chem.
17. Takayama, M., S. Itoh, T. Nagasaki, and I. Tanimizu. 1977.
A new enzymatic method for determination of serum choline-con-
taining phospholipids. Clin. Chim. Acta 79:93–98.
18. Cobas Bio; Roche, Basel, Switzerland.
19. Assman, G., H. Schriewer, G. Schmitz, and E.-O. Hagele.
1983. Quantification of high-density lipoprotein cholesterol by pre-
cipitation with phosphotungstic acid/MgCl
. Clin. Chem. 29:2026–
20. Wybenga, D. R., and J. A. Inkpen. 1974. Lipids. Pages
1421–1493 in Clinical Chemistry: Principles and Techniques. R. J.
Henry, D. C. Cannon, and J. W. Winkelman, ed. Harper &Row,
New York.
21. To extract liver total cholesterol, the thawed livers were
homogenized with four volumes of ethanol and saponified with etha-
nolic KOH at 50°C overnight. The cholesterol was then extracted
with petroleum ether, dried under nitrogen and dissolved with ethanol
prior to measurements. The extraction of free cholesterol from liver
was identical to that of total cholesterol, except for omission of the
saponification step.
22. Genstat Committee. 2000. Reference manual. Numerical
Algorithms Group Ltd., Oxford, UK.
23. Deyoe, C. W., R. E. Davies, R. Krishnan, R. Khaund, and
J. R. Couch. 1962. Studies on the taste preference of the chick. Poult.
Sci. 41:781–784.
24. Lee, K-W., H. Everts, H. J. Kappert, M. Frehner, R. Losa,
and A. C. Beynen. 2003. Effect of dietary essential oils on growth
performance, digestive enzymes and lipid metabolism in female
broiler chickens. Br. Poult. Sci. 44:450–457.
25. Elson, C. E. 1995. Suppression of mevalonate pathway
activities by dietary isoprenoids: Protective roles in cancer and car-
diovascular disease. J. Nutr. 125:1666S–1672S.
26. Youn, B-S., K. Tanaka, S. Ohtani, and U. Santoso. 1993.
Effect of dietary cholesterol on 3-hydroxy-3-methylglutaryl CoA
reductase activity of growing chicks. Anim. Sci. Technol. (Jpn.)
27. Mol, M. A. E., R. C. de Smet, A. H. M. Terpstra, and C.
E. West. 1982. Effect of dietary protein and cholesterol on cholesterol
concentration and lipoprotein pattern in the serum of chickens. J.
Nutr. 112:1029–1037.
28. Hermier, D., and J.-D. Dillon. 1992. Characterization of
dietary-induced hypercholesterolemia in the chicken. Biochim. Bio-
phys. Acta. 1124:178–184.
29. Yasni, S., K. Imaizumi, K. Sin, M. Sugano, G. Nonaka,
and Sidik. 1994. Identification of an active principle in essential
oils and hexane-soluble fractions of Curcuma xanthorrhiza Roxb.
Showing triglyceride-lowering action in rats. Food Chem. Toxicol.
30. Qureshi, A. A., W. R. Mangels, Z. Z. Din, and C. E. Elson.
1988. Inhibition of hepatic mevalonate biosynthesis by the monoter-
pene, d-limonene. J. Agric. Food Chem. 36:1220–1224.
The authors are indebted to A. Lankhorst for technical assistance.
K-W. Lee was supported by the National Institute for International
Education Development, South Korean Ministry of Education.
... The active ingredients in these medicinal plants' leaves, stems, seeds, roots, and barks are extremely helpful in treating a variety of illnesses and enhancing digestion, both of which might enhance the performance of those who consume them (Ashayerizadeh et al., 2009). Some essential oils such as thymol and cinnamaldehyde have generally been recognized as safe, which is endorsed by the Flavor and Extract Manufacturers' Association and Food and Drug Administration of the USA (Lee et al., 2003). In addition to their antimicrobial activity (Dorman and Deans, 2000), phytobiotic compounds exhibit antioxidants activities (Botsoglou et al., 2002) and can stimulate animal digestive systems (Ramakrishna et al., 2003) by increasing digestive enzymes secretion and improving the utilization of digestive products through enhanced liver functions (Hernandez et al., 2004). ...
... The plasma content of feed could be linked to the effects of the essential oils in summer savory foods on digestion. In broilers, feed supplementation with thymol was found to greatly improve pancreatic action (Lee et al., 2003). Protein digestibility improved due to increased pancreatic proteases, which could explain why the SSE-supplemented sets had lower uric acid levels. ...
Full-text available
This review aims to measure the different aspects of summer savory including biological activity, medicinal properties, nutritional value, food application, health prospective and their usage as a feed additive in broilers. However, the herb-related toxicity is also overviewed. Summer savory leaves are abundant in total phenolic compounds (rosmarinic acid and flavonoids) that have an powerful antioxidant impact. The rosmarinic (𝛼-O-caffeoyl-3,4-dihydroxy-phenyl lactic) acid are identified in summer savory as a main component. According to phytochemical investigations, tannins, volatile oils, sterols, acids, gums, pyrocatechol, phenolic compounds, mucilage and pyrocatechol are the primary compounds of Satureja species. Summer savory extract shows considerable biological potential in antioxidant, cytotoxic, and antibacterial assays. Regarding antioxidant activity, the summer savory extract is display an inhibitory concentration for lipid peroxidation. Summer savory has also Fe (III) reductive and free radical scavenging properties. Summer savory is also contained minerals and vitamins. . Sammer savory has important biological properties including antimicrobial activity, antioxidant activity, protection Jurkat T Cells, Alzheimer's disease, cancer, anti-infection, cardiovascular diseases, antidiabetic and anti-cholesterol effects. The leaves and stems of this plant are employed in the food, feed and pharmacological industries due to their antioxidant properties and substantial nutritional contents. Conclusively, summer savory is strongly recommended for human health due to its versatile properties and medicinal use.
... Some studies report that the use of thymus medicinal plant offering 60 mg/kg in the diet increased weight and improve feed conversion ratio(Denli et al. 2004), similar to the results of the present experiment. Also, carvacrol as one of the main components of the thymus plant when fed at 200 mg/kg in the diet favourably improved feed conversion ratio of broiler chickens(Lee et al. 2003).The three main compounds of thymus essential oil are carvacrol, thymol, and terpinene(Laila et al. 2017), which, due to their antioxidant, antimicrobial, and antiseptic properties, can provide better digestion and absorption of nutrients and increase the body weight and feeding e ciency in poultry by reducing the harmful microbial population of the digestive system and improving the health and immunity of chickens. The presence of harmful bacteria causes chronic intestinal in ammation and nutrient absorption disorders. ...
Full-text available
The present experiment was conducted to investigate the effects of F. subpinnata powder (FSP) on performance, carcass characteristics, blood parameters, immune system, microbial population, intestinal morphology, and percentage of fatty acids in the breast meat of broiler chickens. To conduct the experiment, 300 day-old male chickens from the ROSS 308 strain were used in the form of a completely random design with 4 treatments and 5 replicates, with each replicate containing 15 chickens. The experimental treatments were, respectively: 1) control with base diet (without additives), 2) base diet + 1% FSP, 3) base diet + 2% FSP, and 4) base diet + 3% FSP. The results showed that the feed intake and weight gain increased in the treatments containing 2% and 3% FSP when compared to the control (P<0.05). Cholesterol and ALT levels in the treatment containing 3% FSP were lower that the control (P<0.05), while the concentration of glutathione peroxidase enzyme in the treatment containing 3% FSP significantly increased (P<0.05). Thymus weight and antibodies produced against AIV in all three levels of FSP increased significantly compared to the control (P<0.05). The population of lactobacilli and coliforms in the treatments containing FSP increased and decreased significantly compared to the control (P<0.05). The length and width of the intestinal villi of the chickens that were fed with 3% of FSP had a significant increase compared to the control (P<0.05). The percentage of saturated fatty acids in the breast decreased significantly with the consumption of all three levels of FSP (P<0.001). In general, the results showed that the use of 3% FSP in the broiler diet increased the efficiency of growth performance and enzyme activity, while strengthening the immune system, favourably altering the intestinal microbial population, and reducing the fat in breast meat.
... Some essential oils obtained from different sources were used in broiler diets to determine the effects on growth performance, digestibility and digestive systems [7][8][9][10]. Several researchers showed that the supplementation of some essential oils increased the live weight [11] and improved feed conversion ratio [12][13][14][15]. ...
Full-text available
The phytobiotic effects of feed-grade and liquid Oregostim were evaluated and compared on the performance characteristics, haematology and serum biochemistry of finisher broilers. 180 Marshal Broilers at 4wks were allotted into three treatments, T 0 (control), T 1 (3g/10kg feed-grade) and T 2 (3ml/10ltrs liquid), each was replicated thrice, with each replicate having 20 birds. Feed and water were given ad libitum, the feeding trial was for 4wks. The live BW for T 1 (1.73kg) is not significantly (p>0.05) different from T 2 (1.70kg), but T 1 and T 2 are greater than T 0 (1.52kg). The BWG, FCR and mortality % for broilers in T 1 and T 2 are significantly (p<0.05) superior to broilers in T 0 (control). The PCV for T 1 (24.33 ± 2.33) is not significantly (p>0.05) different from T 2 (23.30 ± 3.79), both are significantly (p<0.05) greater than T 0 (21.33 ± 3.28), the [Hb] and MCV are also the same for T 1 and T 2, but are significantly (p<0.05) greater than T 0 .There are no significant (p>0.05) differences among all the other parameters of performance characteristics (FI), haematological (RBC, WBC, MCV) and all serum biochemical indices across the treatments. Either feed-grade Oregostim (3g/10kg feed) or liquid Oregostim (3ml/10 ltr water) is recommended for use in finisher Broilers.
... Improved efficiency of nutrient metabolism could lead to improved growth performance indices. However, performance criteria cannot always be used to determine the impacts of phytogenic supplements or their active ingredients (Lee et al., 2003). In addition, plant-derived active components such as tannins, flavonoids, and saponins have been used in many in vitro and in vivo studies (Abdelli et al., 2021;Agubosi et al., 2022;Iyayi et al., 2021;Kostadinović and Lević, 2018). ...
Natural antibiotic substitutes have recently been used as growth promoters and to combat pathogens. Therefore, this study aimed to assess the effects of adding Magic oil (nano-emulsified plant oil) at different growing periods on growth performance, histomorphology of the ileum, carcass traits, and blood biochemistry of broiler chickens. A total of 432-day-old Ross 308 chicks were randomly assigned to 1 of 6 water supplementation treatment groups based on growing periods, with 4 groups of Magic oil programs compared to probiotic (Albovit) as a positive control and nonsupplemented group as a negative control, with 9 replicates each with 8 birds (4♂ and 4♀). The periods of adding Magic oil Magic oil were 35, 20, 23, and 19 d for T1, T2, T3, and T4, respectively. Birds' performance was evaluated during 0 to 4, 4 to 14, 21 to 30, 30 to 35, and overall days old. Carcass parameters, blood chemistry, and ileal histomorphology were examined on d 35. The findings showed that birds in the T4 group of the Magic oil supplementation program (from 1 to 4 and 21 to 35 d of age) consumed 1.82% and 4.20% more food, gained 3.08% and 6.21% more, and converted feed to meat 1.39% and 2.07% more than Albovit and negative control, respectively, during the experiment (1-35). Magic oil particularly T1 (Magic oil is supplemented throughout the growing period) and T4 programs improved intestinal histology compared to the negative control. There were no changes (P > 0.05) between treatments in carcass parameters and blood biochemistry. In conclusion, water supplementation with Magic oil for broilers improves intestinal morphometrics and growth performance similar to or better than probiotic, especially during brooding and overall periods. Further studies are needed to evaluate the effect of adding both nano-emulsified plant oil and probiotics on different parameters.
... Essential oils are used as a mixture of properties in raw materials in the cosmetics, soap, and detergent industries, pharmaceuticals, food and beverage products, and other products for the health and productivity of livestock. In the livestock sector, essential oils for broiler chickens, such as carvacrol in female broilers, have also been developed to reduce Feed Conversion Ratio (FCR) and lower plasma triglycerides [1,2]. The provision of flavonoids, hesperetin, and naringenin extracted from the orange peel as supplementary feed has antioxidant properties and improves the performance of laying hens while producing eggs with lower cholesterol content [3]. ...
There are millions of plants worldwide, yet most of them have not been investigated for their medicinal properties. The development and recognition of medicinal plants increase at an exponential rate in industrialized and developing nations, resulting in research works on medicinal plants congregating toward therapeutic needs. The remarkable diversity of both chemical structure and biological activities of naturally occurring secondary metabolites, the utility of novel bioactive natural compounds as biochemical probes, the development of novel and sensitive techniques to detect biologically active natural products paved way to improved approaches to isolate, purify, and structurally characterize these bioactive constituents, and advancement in solving the demand for supply of complex natural products.The main focus of this review is to highlight the potential benefits of the Lamiaceae plant derived from multiple compounds and the importance of phytochemicals for the development of biocompatible therapeutics. In addition, this review focuses on problems encountered in medicinal plant research and discusses future directions. This review suggests that conservation strategies and resource management should be considered for sustainable utilization of medicinal plants. This review also recommends that the medicinal plant research should focus on tap plant components of Orthosiphon and deliver the most beneficial health products.KeywordsLamiaceae Orthosiphon Natural productsNatural drugsConservationSustainable utilization
Conference Paper
Full-text available
This study was designed to determine the growth performance and nutrient digestibility of finisher broiler chickens fed Denettia tripelata leaf meal as feed additive. Two Hundred broiler chickens were used for the experiment. Four experimental diets were formulated and labeled T1, T2, T3 and T4. T1 (control) had no Denettia tripelata leaf meal while T2, T3 and T4 contain Denettia tripelata leaf meal at 100g, 200g and 300g/100kg feed respectively. The birds were divided into four groups of fifty birds and each group was assigned one treatment diet in a completely randomized design (CRD). Each group was sub-divided into five (5) replicates of 10 birds each. Feed and water were supplied ad libitum and data collected were analyzed. The result showed significant (P<0.05) differences in the final weight and body weight gain of the birds. T4 had the highest significant (P<0.05) final weight and body weight gain values followed by T3. The feed intake and feed conversion ratio of the birds were statistically similar (P>0.05) across the treatments. Significant differences (P<0.05) were observed in nutrient digestibility of the birds. Significant (P<0.05) differences were also observed in crude protein, crude fibre, Ash and ether extract values. It was concluded that D. tripelata leaf meal could be added to broiler diet at 300g/100kg feed without deleterious effect on the growth performance and nutrient digestibility of the birds.
Full-text available
Background: Salmonellosis is one of the important diseases in the poultry industry, which also causes public health concerns. Objectives: We studied the effects of enrofloxacin and herbal medicines on growth performance, blood parameters, meat oxidation, and cecal microbial population in broilers challenged with Salmonella enterica serovar Typhimurium (ST). Methods: A total of 240 one-day-old (male) Ross 308 broiler chicks were randomly divided into 6 groups: negative and positive control, enrofloxacin, and three herbal medicines (A, B, and C) containing different proportions of cinnamon, thyme, licorice, and marjoram extracts with compounds of organic acids. The dosage of enrofloxacin and A, B, and C herbal medicines were 1, 1, 1, and 2 mL/L in drinking water, respectively, prescribed from days 16 to 21. On day 10, all groups except negative control were challenged with 1 mL suspension containing 1×107 CFU/mL ST. Performance traits were measured in intervals of 1-10, 11-24, 25-42, and 1-42 days. Blood parameters, meat oxidation, and cecal microbial population were measured on day 21. Results: Among the challenged groups, medicine C and enrofloxacin showed the lowest levels of Salmonella infection (P<0.05). Medicine B had a better effect on performance traits (P<0.05). Medicine A had the lowest amount of malondialdehyde in meat. Medicines A and B caused the lowest cholesterol and triglyceride concentration in serum (P<0.05). Conclusion: The above-mentioned herbal medicines can be used as beneficial additives in poultry nutrition to improve growth performance, reduce the Salmonella population in the gastrointestinal tract, and cholesterol, triglycerides, and meat oxidation.
Full-text available
This study aimed to evaluate the effect of oregano extract added to commercial diets on zootechnical performance parameters, carcass yield, immunological conditions, morphometry, and intestinal pH for free-range broiler chickens raised under sanitary challenge conditions. Three hundred chicks of the strain ‘Heavy red’ were used and distributed in a completely randomized experimental design with five treatments and six replications, totaling 30 experimental units, each consisting of 10 birds. The treatments were: T1: Basal diet without oregano extract (OE); T2: Basal diet with OE (150 mg/kg); T3: Basal diet with OE (250 mg/kg); T4: Basal diet with OE (350 mg/kg); T5: and Basal diet with OE (450 mg/kg). There was a significant effect on feed intake, weight gain, feed conversion, feed efficiency, heterophil/lymphocyte ratio (H/L), and intestinal morphometry. No significant differences were observed in viability, carcass yield, intestinal pH, lymphoid organs, gizzard, heart, and intestine. Oregano extract influenced the liver yield and abdominal fat of broilers. Overall, the inclusion of oregano extract at the level of 350 mg/kg provided better results. Phytogenic additives; Alternative poultry farming; Medicinal plants
Full-text available
THE EARLY WORK on the sense of taste of the fowl has been reviewed by Kare et al. (1957). Differences in experimental methods limited the comparison of the results of this early work. Kare et al. (1957) conducted studies to determine flavors which evoked a strong taste reaction in the fowl. These authors chose water as the medium to test flavors and found a rejection of earthy flavors such as costus and sandalwood. Other flavors were found to be accepted or rejected depending on the concentration of the flavor, indicating variable effects of flavors depending on the concentration. It was also observed that the classification of taste recognized by man, such as sweet, salt, sour and bitter does not appear to apply t o the fowl. Histological studies by Lindenmaier and Kare (1959) on chickens showed that taste buds were found only on the base of the tongue and floor . . .
Full-text available
肝臓に次いで生体内コレステロール合成の臓器とされている小腸でのコレステロール合成が飼料にコレステロールを添加した際にどのような影響を受けるかを粘膜上皮細胞におけるHMG-CoA reduc-tase活性を測定し,検討した,成長中ヒナの飼料にコレステロールを添加することによって,肝臓および空腸におけるHMG-CoA reductase活性は,コレステロール無添加飼料給与に比べて,統計的に有意に低下し,回腸では低下する傾向が観察された.空腸でのこの酵素の活性は回腸より高かった.コレステロール添加飼料を給与すると,血清中のエステル型と遊離型コレステロール濃度,肝臓および空腸と回腸の上皮細胞中の遊離型コレステロール含量は,コレステロール無添加飼料給与に比べて統計的に有意に高かった.
Animal feed additives are used worldwide for many different reasons. Some help to cover the needs of essential nutrients and others to increase growth performance, feed intake and therefore optimize feed utilization. They can positively effect technological properties and product quality. The health status of animals with a high growth performance is a predominant argument in the choice of feed additives. In many countries the use of feed additives is more and more questioned by the consumers: substances such as antibiotics and β-agonists with expected high risks are banned in animal diets. Therefore, the feed industry is highly interested in valuable alternatives which could be accepted by the consumers. Probiotics, prebiotics, enzymes and highly available minerals as well as herbs can be seen as alternatives to metabolic modifiers and antibiotics.
The adaptive increase in avian hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity following fasting and refeeding was muted when the monoterpene d-limonene was fed. The suppression of the induction of HMG-CoA reductase activity was dose dependent to 100 ppm dietary d-limonene and additive to that of dietary cholesterol. Noninduced hepatic HMG-CoA reductase activity in rats fed a diet containing 1.0% d-limonene was 55% of the activity in rats fed a control diet.
Oral dosages of 107 synthetic and natural flavourings and structurally-related compounds were administered by intubation to the mouse, rat or guinea-pig. Animals were observed usually for 2 weeks during which time the development of toxic signs was followed and time of death recorded. The acute oral LD50 of each compound was determined.RésuméOn administra par intubation des doses de complexes faits de 107 condiments synthétiques et naturels, de structure chimique voisine, à des souris, des rats et des cobayes. On observa habituellement les animaux pendant 2 semaines, durant lesquelles on suivit le développement de signes toxiques et on nota la date de la mort. Pour chaque complexe on détermina la dose orale limite au-delà de laquelle commence l'intoxication aiguë.Zusammenfassung107 synthetischen un natürliche Geschmackszusätze und strukturverwandte Verbingdungen wurden durch Intubation an Mäuse, Ratten und Meerschweinchen verabreicht. Die Tiere wurden gewöhnlich 2 Wochen lang unter Beobachtung gehalten, während welcher Zeit die Entwicklung toxischer Symptome verfolgt und die Zeit des Todeseintritts registriert wurde. Die akute orale mittlere tödliche Dosis jeder Verbindung wurde festgestellt.
Diets supplemented (1 mmol/kg) with thymol, carvacrol, and β-ionone significantly decreased the serum cholesterol levels of cockerels. These mevalonate-derived end products of plant secondary metabolism (isoprenoids) had no impact on two cytosolic prenyl alcohol (and ethanol) dehydrogenase activities; each treatment increased microsomal geranyl pyrophosphate pyrophosphatase activity by greater than twofold. The structural diversity of the isoprenoids which suppress cholesterol synthesis may be reconciled by their ability to increase pyrophosphatase activity, thus leading to the production of the endogenous, post-transcriptional regulator of 3-hydroxy-3-methyglutaryl coenzyme A reductase activity.
The effect of 2% dietary cholesterol on the distribution of cholesterol among the plasma lipoproteins was studied in 2-week old male chickens. Very-low-, intermediate-, low- and high-density lipoproteins (VLDL, IDL, LDL and HDL) were separated from plasma by density gradient ultracentrifugation in order to determine their concentration and chemical composition. VLDL were furthermore characterized as concerned their size, mobility and protein content. The lipoprotein profile was quantitatively and qualitatively normal in the control group (n = 6) fed the diet without cholesterol, HDL representing the major lipoprotein class (5.06 ± 0.36 g/l) and the main carrier of cholesterol. Birds fed the cholesterol containing diets for 5 weeks (n = 6) exhibited a dramatic hypercholesterolemia (1.60 ± 0.89 g/l free cholesterol and 6.70 ± 3.22 g/l cholesteryl esters) and a shift in their lipoprotein pattern, with an accumulation of β-VLDL (6.08 ± 4.21 g/l) and a marked decrease in HDL level (3.53 ± 0.91 g/l). The decrease or absence of LDL was balanced by a considerable amount of β-VLDL remnants (namely IDL), so that the concentration of IDL + LDL considered as a whole was not modified significantly (2.10 ± 0.95 g/l compared to 1.66± 1.13 g/l in controls). Chicken β-VLDL, smaller in size (31.0 nm) than control VLDL (33.5 nm), were typically enriched in cholesterol (67%) but they lacked apoE. About 60% of plasma cholesterol was associated with β-VLDL which therefore represented the main atherogenic lipoprotein class and were probably responsible for the greater amount of cholesterol found in the aorta in these chickens (2.44 ± 0.99 mg/g aorta vs. 1.32 ± 0.57 in controls). Since LDL were very reduced or absent, the cholesterol-fed chicken provides a suitable model in which to study the role of β-VLDL in atherogenesis.
Fifty plant essential oils were examined for their antibacterial properties against 25 genera of bacteria. Four concentrations of each oil were tested using an agar diffusion technique. The ten most inhibitory oils were thyme, cinnamon, bay, clove, almond (bitter), lovage, pimento, marjoram, angelica and nutmeg. The most comprehensively inhibitory extracts were angelica (against 25 genera), bay (24), cinnamon (23), clove (23), thyme (23), almond (bitter) (22), marjoram (22), pimento (22), geranium (21) and lovage (20).
Carvacrol, (+)-carvone, thymol, and trans-cinnamaldehyde were tested for their inhibitory activity against Escherichia coli O157:H7 and Salmonella typhimurium. In addition, their toxicity to Photobacterium leiognathi was determined, utilizing a bioluminescence assay. Their effects on the cell surface were investigated by measuring the uptake of 1-N-phenylnaphthylamine (NPN), by measuring their sensitization of bacterial suspensions toward detergents and lysozyme, and by analyzing material released from cells upon treatment by these agents. Carvacrol, thymol, and trans-cinnamaldehyde inhibited E. coli and S. typhimurium at 1-3 mM, whereas (+)-carvone was less inhibitory. trans-Cinnamaldehyde was the most inhibitory component toward P. leiognathi. Carvacrol and thymol disintegrated the outer membrane and released outer membrane-associated material from the cells to the external medium; such release by (+)-carvone or trans-cinnamaldehyde was negligible. Of the tested components, carvacrol and thymol decreased the intracellular ATP pool off. coli and also increased extracellular ATP, indicating disruptive action on the cytoplasmic membrane.