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BRIEF RESEARCH REPORT
published: 25 September 2020
doi: 10.3389/fvets.2020.545359
Frontiers in Veterinary Science | www.frontiersin.org 1September 2020 | Volume 7 | Article 545359
Edited by:
Javiera Cornejo Kelly,
University of Chile, Chile
Reviewed by:
Cengiz Gokbulut,
Balikesir University, Turkey
Begum Yurdakok Dikmen,
Ankara University, Turkey
Mohamed E. Abd El-Hack,
Zagazig University, Egypt
Vincenzo Tufarelli,
University of Bari Aldo Moro, Italy
*Correspondence:
Benito Soto-Blanco
benito@ufmg.br
Specialty section:
This article was submitted to
Animal Nutrition and Metabolism,
a section of the journal
Frontiers in Veterinary Science
Received: 24 March 2020
Accepted: 26 August 2020
Published: 25 September 2020
Citation:
Teixeira MdS, Triginelli MV, Costa TdA,
Lara LJC and Soto-Blanco B (2020)
Effects of Caffeine on Egg Quality and
Performance of Laying Hens.
Front. Vet. Sci. 7:545359.
doi: 10.3389/fvets.2020.545359
Effects of Caffeine on Egg Quality
and Performance of Laying Hens
Mailson da Silva Teixeira 1, Marcela Viana Triginelli 2, Thaís de Ataíde Costa 1,
Leonardo José Camargos Lara 2and Benito Soto-Blanco 1
*
1Department of Animal Science, Veterinary College, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil,
2Department of Veterinary Clinics and Surgery, Veterinary College, Universidade Federal de Minas Gerais, Belo Horizonte,
Brazil
This study’s objective was to determine the effects of caffeine intake at various levels,
incorporated in the layers’ food, on performance and egg quality of hens. A total
of 576 hens, aged 56 weeks, were used. The layers were fed rations containing 0
(control), 150, 300, or 450 ppm of caffeine for 12 weeks. During the experimental
period, performance parameters (weight, feed consumption, and livability) and egg
production and quality (weight, Haugh unit, percentages of yolk, albumen and eggshell,
yolk color, eggshell thickness, and resistance, and calcium and phosphorus eggshell
contents) were evaluated. The highest concentration of caffeine in the diet (450 ppm)
promoted a significant increase in the mortality of hens (1.45% per week) compared
to controls (0.23%). There was a reduction in feed consumption by hens, decreased
egg production, and reduced eggshell thickness and percentage, with the increase of
caffeine. The egg yolk percentage was increased, and the eggshell percentage was
reduced in the groups treated with 300 and 450 ppm of caffeine. Furthermore, reduced
eggshell thickness was found in all groups that received caffeine. However, it was found
that 150 ppm of caffeine in the food did not cause significant changes in most egg
production and quality parameters. In summary, caffeine consumption by laying hens
increased mortality rate and promoted deleterious effects on chicken production and
egg quality at concentrations of 300 and 450 ppm.
Keywords: caffeine, coffee husks, chicken, eggs, laying hens
BACKGROUND
Caffeine (1,3,7-trimethylxanthine) is a purine alkaloid synthesized using xanthosine formed from
purine nucleotides (1). This compound is a known antagonist of adenosine A1, A2A, and A2B
receptors in the central nervous system and peripheral tissues (2). Caffeine is found in plants such as
coffee (Coffea spp.), tea plant (Camellia sinensis), cola (Cola nitida), cocoa (Theobroma cacao), maté
(Ilex paraguariensis), and guaraná (Paullinia cupana) (1). Thus, humans regularly consume caffeine
through the food and beverages derived from these plants; and in this process, large amounts of
by-products are generated. These by-products can be used in animal feed, such as coffee husks (3),
cocoa bean shell (4,5), and green tea powder (6,7). Due to the energy levels required by laying
hens, fiber sources are essential, and they are being increasingly studied to improve their welfare
due to changes in the speed of passage of food in the gastrointestinal tract and consequent reduction
in mortality from cannibalism and to reduce the cost of feed (3). Wheat bran is the most used
fiber source, but it has achieved high prices in tropical countries, and alternative fiber sources have
been used.
Teixeira et al. Caffeine-Induced Changes in Eggs
Coffee husks contain high levels of fiber, and the concentration
of crude proteins ranges from 6.9 to 12% (3,8,9). Coffee husks
have been used as a component of food for animal species,
including laying hens (3), pigs (10), sheep (8), and calves (9).
Cocoa bean shells were found to contain 6.78–13.63% of crude
protein and 12.75–33.0% of crude fiber (4,5), and have been used
for feeding a wide variety of livestock species (11). The addition
of green tea powder to hens’ food aims to improve egg nutritional
quality by increasing vitamin E levels and reducing cholesterol
and crude fat (7). The amount of caffeine in the fresh coffee husk
is about 10.0 mg/g (12), from 1.59 to 4.21 mg/g in cocoa bean
shells (13), and about 25.9 mg/g in green tea powder (7).
The quality of eggs produced was negatively affected in laying
hens fed with by-products of caffeine-containing plants, such as
coffee husks (3), cocoa bean shell (4), and green tea powder (6,7).
The adverse effects observed in egg production may be promoted
by caffeine. However, no studies in the literature evaluated the
effects of pure caffeine on egg quality, the performance of laying
hens, and the safety of caffeine consumption.
Thus, the aim of this study was to determine the effects of
caffeine intake (incorporated into hen feed at various levels)
on the egg production and performance of laying hens. Our
hypothesis is that caffeine consumption by laying hens might
interfere with egg production and quality in a dose-dependent
way. The generated data is useful for determining the amount
of caffeine-containing plant by-products that could be used as
feed ingredients, without affecting the health and performance
of laying hens.
MATERIALS AND METHODS
Animals
The experiment was conducted at the Experimental Farm “Prof.
Hélio Barbosa” of the Veterinary School, Federal University of
Minas Gerais (UFMG), located in the municipality of Igarapé,
MG, Brazil. The Animal Use Ethics Committee of UFMG
(protocol # 28/2018) approved all procedures described in this
study. The possibility of animal death without euthanasia was
stated in the study protocol submitted to the animal ethics
committee because the expected mortality rate of laying hens
ranges from 0.8 to 1.5% per week (14).
A total of 576 Lohmann LSL R
laying hens aged 56 weeks were
used. The hens were housed in a conventional, non-climatized
laying house, equipped with cages at a density of 333 cm2/hen,
with six hens per cage. Animal partitions were isolated by a wood
splitter, preventing hens from accessing the feed from another
partition. All hens were included in the experiment on the same
date. Feeding was performed daily, and egg collection occurred
four times a day. The light program used was 14 h of light/day,
with 12 h of natural light and 2 h of artificial light (1 h of artificial
light at dawn and 1 h in the early evening).
Experimental Design
The hens were distributed in 24 experimental plots for 12
experimental weeks, 1 week after dietary standardization. The
hens selected for the experiment had weight uniformity.
The experimental design was completely randomized of four
TABLE 1 | Ingredients and nutritional values of the basal diet.
Ingredients %
Corn grain 62.000
Soybean bran (45% CPa) 20.402
Wheat bran 3.000
Calcitic limestone 9.820
Meat and bone meal (40% CP) 4.000
Salt 0.380
Vitamin and mineral supplementb0.200
DL-methionine 0.140
L-Lysine 0.040
Nutritional values Amount
AMEnc(kcal/kg) 2677.9954
Crude protein (%) 16.3585
Available phosphorus (%) 0.3205
Calcium (%) 4.0458
Sodium (%) 0.1821
Digestible lysine (%) 0.7470
Digestible Met+Cys (%) 0.5879
Digestible methionine (%) 0.3681
Digestible threonine (%) 0.5403
aCP—crude protein.
bComposition per kg of product: Vitamin A: 8,000,000 UI, Vitamin D3: 2,100,000
UI, Vitamin E: 7,000 mg, Vitamin K3: 2,000 mg, Vitamin B1: 1,000 mg, Vitamin B2:
3,000 mg, Vitamin B6: 700 mg, Vitamin B12: 6,000 mg, Folic acid: 100 mg, Biotin: 10 mg,
Niacin: 20 g, Pantothenic acid: 2,000 mg, Manganese: 55,000 mg, Zinc: 40,000mg, Iron:
50,000 mg, Cupper: 6,000 mg, Cobalt: 100 mg, Iodine: 1,000 mg, Selenium: 200 mg,
Calcium: 10,000 mg.
cAMEn—Nitrogen-corrected apparent metabolizable energy.
treatments with three different amounts of caffeine (anhydrous
caffeine, Sulfal, Belo Horizonte, MG, Brazil) per ton of feed: 0
(control), 150, 300, and 450 g/ton. The highest concentration was
based in an earlier study that showed impaired egg production
by laying hens fed coffee husks at 42.5 g/kg (3), that is expected to
contain caffeine at ∼10.0 mg/g (12), equal to 425 g of caffeine/ton
of feed. Ingredients and nutritional composition of the basal diet
are shown in Table 1. Hens received water and feed ad libitum.
Bodyweight was determined on the first and last days of
the experimental period, and all hens from each partition
were weighed together. Egg production was recorded daily; egg
production per housed hen, and the percentage of weekly and
total laying were calculated. Feed intake was determined weekly.
Feed conversion was obtained by the ratio of the total feed
consumed by the hens of each partition to the total weight of
eggs laid in the same period (kg feed/kg eggs). The animals were
monitored daily, and the number of hens was recorded daily to
determine the mortality rate. All the research staff was previously
trained for adequate animal care and handling.
Analysis of Eggs
Eggs were collected after experimental periods of 3, 7, and
12 weeks, when the hens were 59, 63, and 68 weeks old,
respectively. All eggs produced on these days were identified and
weighed. Four eggs per repetition were randomly separated for
assessments of egg quality. Evaluated parameters were weight,
Frontiers in Veterinary Science | www.frontiersin.org 2September 2020 | Volume 7 | Article 545359
Teixeira et al. Caffeine-Induced Changes in Eggs
TABLE 2 | Initial and final body weight (in kg), body weight gain (in kg), and feed consumption (in g/day) of laying hens fed rations containing different concentrations of
caffeine for 12 weeks.
Caffeine in diet Initial body
weight (kg)
Final body
weight (kg)
Bodyweight gain
(g)
Feed
consumption
(g/hen.day)
Consumed
caffeine
(mg/hen)
0 (control) 1.59 ±0.01 1.60 ±0.01a16.8 ±6.99a108.4 ±0.96a0
150 ppm 1.63 ±0.02 1.58 ±0.01a−51.3 ±10.7b109.1 ±0.85a16.365
300 ppm 1.63 ±0.02 1.54 ±0.01b−97.8 ±14.5c106.4 ±1.05a31.920
450 ppm 1.60 ±0.02 1.49 ±0.01c−113.5 ±10.5c98.3 ±1.26b44.235
pn.s. <0.001 <0.001 <0.001 –
Data are shown as mean ±SEM.
a,b,cDifferent letters in the same column show significant difference (p <0.05, ANOVA followed by Tukey test).
n.s., non-significant.
n=24.
TABLE 3 | Number and percentage of produced eggs per laying hen and feed conversion in eggs (in g/egg) of hens fed rations containing different concentrations of
caffeine for 12 weeks.
Caffeine in diet Number of eggs/laying hen Percentage of eggs/laying hen Feed conversion (kg feed/kg eggs)
0 (control) 75.2 ±0.63a90.3 ±2.21a1.82 ±0.33b
150 ppm 73.3 ±1.24a,b 91.3 ±1.64a1.88 ±0.38a,b
300 ppm 68.8 ±1.22c88.2 ±1.33a1.90 ±0.46a,b
450 ppm 60.6 ±2.27d80.7 ±2.19b2.01 ±0.67a
p<0.001 <0.01 <0.05
Data are shown as mean ±SEM.
a,b,c,dDifferent letters in the same column show significant difference (p <0.05, ANOVA followed by Tukey test).
n=24.
Haugh unit (HU), percentages of yolk, albumen and eggshell,
yolk color, eggshell thickness and resistance, and eggshell calcium
and phosphorus content.
HU was determined using a HU measuring device (Ames
model S-8400, Massachusetts, USA). The calculation of HU was
based on albumen height (H) and egg weight (W), as follows:
HU =100 log10 (H – 1.7 W0.37 +7.56) (15). Percentages of
yolk, albumen, and eggshell were determined by the methods
described by Wu et al. (16). The yolk color score was determined
immediately after the egg was broken, comparing the color of
the yolk to a color fan (DSM Yolk Color Fan, 2005—HMB
51548, Basel, Switzerland). The same evaluator performed all
measurements of the yolk color score in the same location.
Eggshell thickness was measured using a digital micrometer
(Ames, Massachusetts, USA), with an accuracy of 0.001 mm,
in three distinct regions of the shell (apical, equatorial, and
basal); results were obtained by the average of measures of
the three regions. Eggshell resistance was measured through
the compression eggshell fracture force test, using a texture
analyzer (TA-XT2, Stable Micro Systems, Surrey, England), as
described by Carvalho et al. (17). Calcium and phosphorus
eggshell contents were pretreated following the method described
by the Brazilian Compendium of Animal Nutrition (18).
Statistical Analysis
For the performance evaluations, the experimental design was
entirely randomized (DIC), consisting of four treatments and six
partitions with 24 hens in each.
For egg quality analysis, the experimental design was
completely randomized, consisting of four treatments and 24
TABLE 4 | Weight of the eggs (in g) produced by laying hens fed rations
containing different concentrations of caffeine for 12 weeks.
Caffeine in diet Experimental period
4 weeks 8 weeks 12 weeks
0 (control) 66.2 ±1.06 66.4 ±1.14 64.3 ±0.96a
150 ppm 65.0 ±1.03 65.5 ±0.92 64.1 ±0.80a,b
300 ppm 64.1 ±0.98 63.1 ±0.82 64.1 ±1.04a
450 ppm 64.2 ±0.73 64.3 ±1.09 60.5 ±1.07b
pn.s. n.s. <0.05
Data are shown as mean ±SEM.
a,bDifferent letters in the same column show significant difference (p <0.05, ANOVA
followed by Tukey test).
n.s., non-significant.
n=24.
eggs per treatment, each egg being considered a repetition. For
analysis of shell resistance, different eggs from the previously
mentioned analysis (new sample collected) were used, likewise
four eggs per repetition at 24 eggs per treatment with each egg
being considered a repetition.
The results are presented as mean ±SEM. The data were
analyzed with the aid of the SAS program and subjected to
analysis of variance (ANOVA) to verify the significant effects
between the simple factors; subsequently, a regression test
between the treatments was performed. Additionally, ANOVA
followed by Tukey test, and Kruskal-Wallis test followed by
Student-Newman-Keuls were performed. The level of statistical
significance was set at p <0.05.
Frontiers in Veterinary Science | www.frontiersin.org 3September 2020 | Volume 7 | Article 545359
Teixeira et al. Caffeine-Induced Changes in Eggs
TABLE 5 | Haugh units of the eggs produced by laying hens fed rations
containing different concentrations of caffeine for 12 weeks.
Caffeine in diet Experimental period
4 weeks 8 weeks 12 weeks
0 (control) 91.8 ±0.74c87.9 ±1.10 86.8 ±1.02b
150 ppm 92.9 ±0.78b,c 87.5 ±1.05 92.9 ±0.83a
300 ppm 94.6 ±1.25a,b 90.1 ±1.10 91.5 ±0.93a
450 ppm 95.7 ±0.89a90.2 ±1.03 94.5 ±1.08a
p0.01 n.s. <0.001
Data are shown as mean ±SEM.
a,b,cDifferent letters in the same column show significant difference (p <0.05, Kruskal-
Wallis test followed by Student-Newman-Keuls test).
n.s., non-significant.
n=24.
RESULTS
The body weights on the last day of the experiment were
significantly lower (p<0.001) in groups fed 300 and 450 ppm
of caffeine than in controls (Table 2). The body weight gain was
lower (p<0.001) in all groups that received caffeine than control
group, but the feed consumption in the entire experimental
period was impaired (p<0.001) only in hens fed the largest dose
of caffeine.
The number of hens that died during the experimental period
was 4, 7, 12, and 25 in groups fed 0 (control), 150, 300, and
450 ppm of caffeine, respectively. All these hens were found
dead without showing any noticeable sign of disease or pain,
and the exact cause of death could not be determined. The log-
rank test showed a significant difference (p<0.0001) in mortality
between the control and 450 ppm groups. However, there was no
significant difference between the control group and the 150 ppm
(p=0.527) or the 300 ppm (p=0.065) groups.
Both egg production and number of eggs per housed hen
(Table 3) were significantly (p<0.05) lower values in hens that
consumed the highest concentration of caffeine in the diet. Feed
conversion was worse in hens fed 450 ppm of caffeine vs. the
control group.
The average egg weight (Table 4) was reduced (p<0.05) only
in the group that received the highest caffeine dosage at 12 weeks
of the experimental period. The HU (Table 5) showed higher
values in eggs from hens fed all concentrations of caffeine vs. eggs
from the control group after 12 weeks.
The percentages of egg components (yolk, albumen,
and eggshell) of the produced eggs are shown in Table 6.
Consumption of 300 and 450 ppm of caffeine in the diet
increased the egg yolk percentage after 12 weeks of the
experiment. Also, caffeine intake was responsible for reducing
the eggshell percentage at all evaluations. On the other hand, the
albumen percentage was not affected.
Thickness and strength of the eggshell and the yolk color
score are presented in Table 7. At all concentrations, caffeine
intake was responsible for lower (p<0.05) eggshell thickness
at all evaluated periods. However, caffeine reduced (p<0.05)
the strength of the eggshell after 4 weeks of the experiment, but
there was no significant difference at later periods. Furthermore,
TABLE 6 | Percentages of yolk, albumen, and eggshell of the eggs produced by
laying hens fed rations containing different concentrations of caffeine for 12 weeks.
Caffeine in diet Experimental period
4 weeks 8 weeks 12 weeks
Percentage of yolk
0 (control) 28.1 ±0.42 27.9 ±0.41 27.4 ±0.27a
150 ppm 28.0 ±0.40 28.6 ±0.35 27.6 ±0.41a,b
300 ppm 28.4 ±0.37 28.9 ±0.45 28.4 ±0.57b
450 ppm 28.2 ±0.40 28.3 ±0.30 28.9 ±0.49b
pn.s. n.s. <0.05
Percentage of albumen
0 (control) 62.3 ±0.45 62.5 ±0.47 62.7 ±0.32
150 ppm 62.6 ±0.43 62.3 ±0.44 63.7 ±0.38
300 ppm 62.6 ±0.40 62.1 ±0.44 63.0 ±0.63
450 ppm 62.9 ±0.42 63.0 ±0.34 62.4 ±0.50
pn.s. n.s. n.s.
Percentage of eggshell
0 (control) 9.61 ±0.14a9.64 ±0.11a9.87 ±0.14a
150 ppm 9.42 ±0.11a9.16 ±0.14a,b 8.72 ±0.18b
300 ppm 9.04 ±0.12b8.95 ±0.10b8.56 ±0.20b
450 ppm 8.93 ±0.14b8.73 ±0.15b8.78 ±0.17b
p<0.001 <0.001 <0.0001
Data are shown as mean ±SEM.
a,bDifferent letters in the same column show significant difference (p <0.05, Kruskal-Wallis
test followed by Student-Newman-Keuls test).
n.s., non-significant.
n=24.
there was interference (p<0.05) in the yolk color score of eggs
from laying hens exposed to caffeine after 8 and 12 weeks of the
experimental period.
DISCUSSION
Feed consumption was impaired in hens from the 450 ppm
caffeine group. Caffeine might interfere with appetite, reducing
energy intake (19,20). However, the mechanism underlying this
effect is still unclear. Furthermore, ingesting caffeine increases
corporal energy consumption. Caffeine was found to increase the
serum release of catecholamines (epinephrine, norepinephrine,
and dopamine) (21) and the oxidation of lipids (22,23).
The group fed 450 ppm caffeine showed an increased
mortality rate, with a mortality rate of 1.45% per week, whereas
the mortality rates of hens fed 0, 150, and 300 ppm caffeine
were 0.23, 0.41, and 0.69%, respectively. The acceptable mortality
rate for caged laying hens is up to 1.2% per week (14), then
the group fed 450 ppm caffeine was the only one showing
a high mortality rate. Increased mortality rates were also
observed in broiler chicks that received caffeine. These chicks
developed pulmonary hypertension syndrome or ascites, with
right ventricular hypertrophy and an increased hematocrit (24).
Furthermore, the stimulating effect of caffeine may induce the
observed reduced feed consumption, generating an energy and
protein deficit. Also, caffeine interferes with the proper function
of the immune system (25,26), which may have increased the
susceptibility of hen chickens to infections.
Frontiers in Veterinary Science | www.frontiersin.org 4September 2020 | Volume 7 | Article 545359
Teixeira et al. Caffeine-Induced Changes in Eggs
TABLE 7 | Thickness and strength of the eggshell and the yolk color score of the
eggs produced by laying hens fed rations containing different concentrations of
caffeine for 12 weeks.
Caffeine in diet Experimental period
4 weeks 8 weeks 12 weeks
Thickness of eggshell (in mm2)
0 (control) 39.4 ±0.63a39.6 ±0.48a39.6 ±0.54a
150 ppm 38.0 ±0.36b37.5 ±0.37b35.6 ±0.66b
300 ppm 36.58 ±0.44b36.5 ±0.39b35.0 ±0.68b
450 ppm 36.5 ±0.59b36.1 ±0.65b35.6 ±0.73b
p<0.0001 <0.0001 <0.0001
Strength of eggshell (in kg/cm2)
0 (control) 5.19 ±0.17a4.41 ±0.16 4.88 ±0.24
150 ppm 3.33 ±0.16b4.21 ±0.21 4.64 ±0.20
300 ppm 3.27 ±0.11b4.20 ±0.17 4.21 ±0.19
450 ppm 3.53 ±0.15b4.49 ±0.19 4.35 ±0.21
p<0.0001 n.s. n.s.
Yolk color score
0 (control) 7.25 ±0.14 6.37 ±0.12b6.00 ±0.20c
150 ppm 7.08 ±0.13 7.25 ±0.12a6.58 ±0.16b,c
300 ppm 6.96 ±0.09 6.96 ±0.09a7.04 ±0.23b
450 ppm 7.04 ±0.13 7.04 ±0.13a7.25 ±0.23a
pn.s. <0.0001 <0.001
Data are shown as mean ±SEM.
a,b,cDifferent letters in the same column show significant difference (p <0.05, Kruskal-
Wallis test followed by Student-Newman-Keuls test).
n.s., non-significant.
n=24.
The quality of produced eggs was negatively affected by
feeding laying hens with by-products of caffeine-containing
plants, such as coffee husks (3), cocoa bean shell (4), and green tea
powder (6,7). In this study, caffeine ingestion negatively affected
the production and quality of eggs. The egg production per hen
was reduced in those fed rations containing 300 or 450 ppm of
caffeine. The egg weight was also reduced in the groups that
consumed the diet containing the highest amount of caffeine after
12 weeks. Additionally, after 12 weeks, the percentage of yolk and
the yolk color score increased in groups treated with 300 and
450 ppm of caffeine, and the HU was augmented in all groups
that received caffeine. The reduced egg weight and increased yolk
percentage, yolk color score, and HU are probable consequences
of the eggs’ lower water content.
The interference of caffeine with egg production can be
attributed to the observed reduction in feed consumption
that could, in turn, generate an energy and protein deficit.
Another hypothesis is that caffeine might interfere directly with
ovarian physiology. In a previous study, female rats fed caffeine
showed increased ovarian production of estradiol and delayed
vaginal opening (27). Furthermore, several studies evaluating
women showed the consumption of coffee and other caffeinated
beverages was linked to a longer delay before becoming pregnant.
This observed effect was proportional to the number of ingested
beverages (28–30), but there is no consensus that caffeine
promotes this effect (31).
Another effect of caffeine observed in the present study was
the harmful interference with the eggshell, characterized by the
reduced thickness and shell percentage at all evaluations. These
effects were also observed in laying hens fed rations containing
4.25% of coffee husk (3). The reduced thickness and percentage
of eggshell may be attributed to caffeine interference on calcium
metabolism due to increased urinary excretion of calcium and
magnesium (32,33). Caffeine may promote hypocalcemia due
to an increased compensatory bone resorption rate and reduce
bone mineral density in laboratory animals (34). In humans,
caffeine intake at high doses increases the risk of developing
osteopenia and osteoporosis (35) and, consequently, augments
the possibility of fractures (36). Thus, it is feasible to suppose that
caffeine ingestion raised the urinary calcium excretion of laying
hens, resulting in a smaller amount of this mineral available for
eggshell formation.
CONCLUSIONS
The present study reveals that caffeine consumption by
laying hens increased the mortality rate and promoted
deleterious effects on hen performance and egg quality
when its concentration in the diet was 300 or 450 ppm.
Consumption of up to 150 ppm of caffeine in the diet did
not significantly interfere in hens or egg production. This
concentration of caffeine in the diet is equivalent to ∼15 kg of
coffee husk, 35.6 kg of cocoa bean shell, and 5.7 kg of green tea
powder per ton of feed, considering that the caffeine content
in these compounds is ∼10.0 mg/g (12), 4.21 mg/g (13),
and 25.9 mg/g (7), respectively. However, doses above this
value may have undesirable consequences on egg production
and quality.
DATA AVAILABILITY STATEMENT
The raw data supporting the conclusions of this article will be
made available by the authors, without undue reservation.
ETHICS STATEMENT
This animal study was reviewed and approved by Animal
Use Ethics Committee of the Universidade Federal de Minas
Gerais—UFMG.
AUTHOR CONTRIBUTIONS
BS-B and LL conceived and designed the experiments. MST,
MVT, and TC performed the experiments. BS-B, LL, and MST
analyzed the data. BS-B and MST drafted the manuscript. All
authors read and approved the final manuscript.
FUNDING
This work was supported by the grant of the Conselho
Nacional de Desenvolvimento Científico e Tecnológico—CNPq
(grant #311182/2017-8).
Frontiers in Veterinary Science | www.frontiersin.org 5September 2020 | Volume 7 | Article 545359
Teixeira et al. Caffeine-Induced Changes in Eggs
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Conflict of Interest: The authors declare that the research was conducted in the
absence of any commercial or financial relationships that could be construed as a
potential conflict of interest.
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