This study was conducted to determine the effects of fermented milk products
and probiotic on performance, carcass characteristics, blood parameters, and
gut microbial population in broiler chickens. A total of 480 one-day-old
Ross 308 broilers were allocated to 30 floor pens in a completely randomized
design with six treatments, five replicates, and 16 chicks (eight males and
eight females) in each replicate. On the first day, the male and female
chicks were weighed and divided by the feather sexing method so that the
average body weight of chicks was approximately equal in each pen. Treatments
consisted of six groups (including control): group 1 had a basal diet and normal drinking water, group 2 had a basal
diet and probiotics (PrimaLac®) in drinking water as recommended by
the manufacturer, group 3 had a basal diet and 2 % yogurt in drinking water,
group 4 had a basal diet and 4 % yogurt in drinking water, group 5 had a basal diet
and 2 % kefir in drinking water, and group 6 had a basal diet and 4 % kefir in
drinking water. Chemical and microbiological characteristics of kefir and
yogurt were measured after each production. The results showed that 4 %
kefir, yogurt, and probiotic at the recommend level in water improved body
weight gain, feed intake, and feed conversion ratio compared with other
groups (P<0.05). The results indicated that treatment had a
significant effect on the carcass yield, intestinal length, thigh yield, and
abdominal fat in male and female chickens (P<0.05). There were no
effects on total bacteria population but the lactobacilli and coliform bacteria
populations showed increasing and decreasing trends, respectively, with 4 % kefir, yogurt, and probiotic supplementation at 28 and 42 d (P<0.05). In
addition, blood glucose and total protein increased when using a high
levels of kefir, yogurt, and probiotic in water, while cholesterol and LDL (low-density lipoprotein)
concentrations were lower in 4 % kefir, yogurt, and probiotic at the
recommended level. Consequently, the results of this study showed that the
use of 4 % kefir, yogurt, and probiotic at recommended level in water
had beneficial effects on the growth performance, intestinal bacteria
population, and blood biochemical parameters in male and female broiler
chickens.
Introduction
For many years, antibiotics were used as growth promoters in the poultry
industry but recently these compounds have been prohibited due to their
frequent use in animal diets and adverse effects on human and
animal health conditions. Therefore, in many countries the prescription of
antibiotics for animal diets has been prohibited (Apata, 2009; Shaddel-Tili
et al., 2017). Hence, replacement of probiotics in the diets may decrease by
use of antibiotics in ruminant and poultry diets (Fuller, 1998). Probiotics
are a live microbial feed supplement that benefits the
host by the intestinal microbial balance. Also, the utilization of
probiotics in animal nutrition can provide healthy foods for humans (Denli et
al., 2003). Similarly, researchers have defined probiotics as an alternative
to antibiotics in animal diets (Fuller, 1998). Probiotics are increasingly
adopted as an alternative to antibiotic growth promoters in poultry diets
(Denli et al., 2003). In recent years, a large amount of research has been
conducted on the use of probiotics in broiler chickens, and the majority of
researchers reported that the use of probiotics improved the
performance of broiler chicks (Jin et al., 1998b; Zulkifli el al., 2000;
Kabir et al., 2004; Mountzouris et al., 2007). The previous studies observed
that the use of probiotics has beneficial effects on poultry performance, For
example, Khaliq and Ebrahimnezhad (2016) concluded that the use of probiotic
from 1 to 42 d in diet improved the performance of broiler chicks. Also,
Arslan and Saatci (2004) demonstrated that the use of 1.5 g kg-1 probiotic in
water or diet improved live weight, feed consumption, and feed conversion
efficiency of Japanese quail.
Fermented milk products are one of the important sources for transferring
beneficial bacteria strains to the human digestive system (Itsaranuwat et
al., 2003). Therefore, milk products contain important bacteria such as
lactobacilli and Bifidobacterium, which have been used in different parts of the world as a probiotic
supplement (Maity et al., 2008). Fermented milk dairy products from a
variety of animals are perhaps the most common fermented foods worldwide
(Farnworth, 2005). Hence, yogurt and kefir are fermented milk products
that have been used as probiotics in animal and human nutrition (Farnworth, 2005).
Yogurt, which is known by many different names in different countries, is a
fermented product which is familiar to consumers (Farnworth, 2005). Moreover,
yogurt is a dairy product that contains useful bacteria such as lactic acid bacteria, Lactobacillus bulgaricus, Streptococcus thermophilus, and L. delbrueckii (Pelczar
et al., 1986). In addition, yogurt can be effectively used as a probiotic in
broiler chickens nutrition (Metchnikoff, 1998; Boostani et al., 2013).
Yogurt also contains 108 CFU mL-1 (where CFU means colony forming units) Streptococcus thermophilus, Lactobacillus delbrueckii (Boostani et al., 2013), 3.7 % protein, 3.4 % fat, and 4.7 % lactose (Nergiz and Seckin, 1998).
Therefore, yogurt can have a direct impact on the health of the digestive
tract by preventing the growth of pathogenic bacteria and maintaining the
balance of beneficial bacteria (Metchnikoff, 1998). Similarly, Khan et al. (2011) compared probiotics, yogurt, and antibiotics and they reported that the use of yogurt-like probiotic has a
significant effect on the performance of broiler chickens.
Kefir is another fermented milk product that is considered probiotic in
animal or human nutrition (Yaman et al., 2006). Also, kefir belongs to the
probiotic group originated from the Caucasus Mountains in Russia and is very
popular in Middle Eastern drinks. Kefir is different from other fermented
milk products because it comes from kefir grains that include a specific
and complex mixture of lactic acid and acetic acid bacteria, and
lactose-fermenting and nonfermenting yeast, which live in a symbiotic
association (Rosa et al., 2017). The properties of kefir are derived from
lactic acid, carbon dioxide, ethyl alcohol, and aromatic compounds that
are obtained during fermentation (Rosa et al., 2017). Kefir is obtained by
fermentation and the activity of lactobacilli such as Lactobacillus lactis, Lactobacillus helveticus, Lactobacillus casei, Streptococcus (S. cremoris, S. lactis), and yeasts (Otles and Cagindi, 2003; Toghyani et al., 2015). Usual kefir (fermented milk provided from kefir grains) contains almost 7.2 % protein, 6.6 % lactic acid, and less than 10 %
fat. Also, kefir usually contains 98–10 (CFU mL-1) of lactic acid
bacteria (Rosa et al., 2017) and 106–7 (CFU mL-1) yeast (Prado et al.,
2015). Similarly, previous research stated that kefir contained
proteins, polysaccharides, ethyl alcohol, lactic acid, fat, minerals, and
vitamins (Magalhaes et al., 2011). Also, some strains of Lactobacillus and yeasts in
kefir grain were previously reported as probiotics such as Lactobacillus delbrueckii subsp. bulgaricus, L. acidophilus, L. plantarum, L. brevis, L. fermentum, L. casei, L. helveticus, L. lactis subsp. lactis, Streptococcus thermophilus, and Saccharomyces cerevisiae (Yaman et al.,
2006). Cho et al. (2013) reported that the use of kefir improved the growth
performance of the broiler chickens. Also, an experiment conducted by
Cenesiz et al. (2008) reported that the use of kefir has a beneficial effect
on blood parameters of broiler chickens. However, kefir is less known than
yogurt and it may contain bioactive ingredients that give it great
health benefits, which means that kefir can be an essential probiotic
product (Farnworth and Mainville, 2003; Farnworth, 2005).
Therefore, it seems that fermented milk products such as kefir and yogurt could
be considered more useful probiotics by farmers; hence, the aim of this
study was to determine the comparison of commercial probiotics with
fermented milk probiotics on the performance of broiler chickens.
Materials and methodsAnimals, breeding, and nutrition
All the chicks were kept under similar management conditions according to
the Ross 308 strain catalogue. Animal handling and experimental procedures were
performed according to the Guide for the Care and Use of Laboratory Animals
by the Islamic Azad University Ethics Committee. A total of 480 one-day-old
Ross 308 broiler chicks were used in this study. On the first day, male and
female chicks were separated by the feather sexing method. At the beginning of
the experiment, the male and female chicks were weighed so that the average
body weight of chicks was approximately equal in each cage. Then the male and
female chicks were allocated to 30 floor pens in a completely randomized design
with six treatments, five replicates, and 16 chicks in each pen (eight males
and eight females) throughout the experimental period, which was 42 d. Broiler
chickens were breeding within floor pens and the dimensions of each pen were
1m×2 m.
A basal diet, considered control, was formulated according to the National Research Council recommendations (NRC, 1994) for the starter, grower, and finisher periods. The
experimental diets are shown in Table 1.
Composition of the basal diet (ingredients and nutrients) given to broiler chickens for 6 weeks.
1 Vitamin mixture provided per kilogram of diet: 3.60 mg vitamin A
(retinol), 0.124 mg vitamin D3 (cholecalciferol), 18.20 mg vitamin E
(alpha-tocopherol), 3.7 mg vitamin K3 (menadione), 3 mg vitamin B1
(thiamine), 15 mg vitamin B12 (cobalamin), 55 mg vitamin B3 (niacin), and 1 mg vitamin B7 (biotin).
2 Mineral mixture provided per kilogram of diet: 50 mg Mn (manganese),
47 mg Zn (zinc oxide), 25 mg Fe (iron), 7.5 mg Cu (copper sulfate), 2.6 mg
I (iodine), and 0.40 mg Se (selenium).
Therefore, there were six experiment groups (including control): group 1 had a basal diet and normal
drinking water, group 2 had probiotics (PrimaLac) in drinking water as recommended by the
manufacturer, group 3 had 2 % yogurt in drinking water, group 4 had 4 % yogurt
in drinking water, group 5 had 2 % kefir in drinking water, and group 6 had 4 %
kefir in drinking water. The duration of the experimental period was 42 d. The feed and water were available ad libitum to broiler chickens.
The commercial probiotic in this study was PrimaLac® (StarLabs Inc.,
Clarksdale, MO, USA), which is a multistrain commercial preparation in
powder form (2×107 CFU g-1) that consists of Lactobacillus acidophilus, L. casei, Enterococcus faecium, and Bifidobacterium bifidum in drinking water.
Kefir preparation
Kefir was prepared from fresh cow milk so that the milk was pasteurized at 80 ∘C for
30 min. After that, the pasteurized milk was cooled down to 25 ∘C
and then the kefir grains were added to whole milk at a proportion of 1:50 (w/v)
for fermentation at temperatures from 22 ∘C. At the end of
fermentation, the kefir grains were removed by filtration from the kefir product
(Rosa et al., 2017; Yaman et al., 2006).
Yogurt preparation
Fresh cow's milk was purchased and heated to 90 ∘C for 10 min,
cooled to 45 ∘C, and inoculated with 3 % starter culture of
Streptococcus salivarius subsp. thermophilus and Lactobacillus delbrueckii subsp. bulgaricus. After fermentation, the yogurt was cooled to room temperature
(21 ∘C) and stored in a refrigerator at 4 ∘C for 12 h
(Nergiz and Seckin, 1998).
Measurement of chemical and microbiological characteristics of
kefir and yogurt
In this study, yogurt and kefir were produced every 7 days. After each
production, the yogurt and kefir were stored in a refrigerator at
4 ∘C. Regarding previous studies, it seems that cold storage can
maintain the chemical and microbiological characteristics of these products
during the 7 days (Irigoyen et al., 2005; Alirezalu et al., 2016). In
addition, chemical and microbiological characteristics of kefir and yogurt
were analyzed each time after production of fermented milk product. For this
purpose, fat, protein, pH contents, lactic acid bacteria, and yeast
in yogurt and kefir were determined according to Marshall (2005). The
average values of chemical and microbiological characteristics in yogurt and
kefir are shown in Table 2.
Analysis of the chemical and microbiological composition of kefir
and yogurt.
1 Results are the average of six analyses ±SD.
2 Values of fat and protein are for 100 g yogurt and kefir samples.
Performance traits
At the end of each period, feed intake (FI), body weight gain (BWG), and
feed conversion ratio (FCR) were measured. European broiler index (EBI) for
the whole period (1 to 42 d) of breeding was calculated using the
following equation.
European broiler index (EBI) = [average daily gain (grams of chick per day, g d-1) ×
viability (%) / (feed conversion ratio, g g-1) ×10] ×100.
Carcass traits
Six chicks (three male and three female) from each replicate were sampled
(close to average weight) for carcass evaluations at 42 d of age,
slaughtered, dissected manually, and weighed. The live body weight,
eviscerated carcass, breast, thing, wings, abdominal fat, liver, and intestine
were excised and weighed individually. The carcass yields were calculated as
a percentage of the preslaughter live body weights of broiler chickens. The
weights of these internal organs were expressed as a percentage of live body
weight. Also, the size of the small intestine was expressed in centimeters.
Gut microbial population
At 24 and 42 d, six chicks (three male and three female) from each
replicate were randomly selected for the measurement of intestinal microbial
population.
For this purpose, 1 g of the composite gut sample from each chicken was
diluted with 9 mL of 0.9 % saline solution and mixed in a vortex. Viable
counts of bacteria in the gut samples were then conducted by plating serial
10-fold dilutions (in 1 % peptone solution) into lactobacilli de Man, Rogosa, Sharpe
agar plates, and MacConkey agar plates (to isolate the Lactobacillus and coliform colonies). The lactobacilli de Man, Rogosa, and Sharpe agar plates were then incubated for 48 h at
37 ∘C under anaerobic conditions. The Lactobacillus and coliform colonies were
conducted immediately after removal from the incubator as described by Kang
et al. (2013) and Khaliq and Ebrahimnezhad (2016). Also, for the
enumeration of anaerobic bacteria, Reinforced Clostridial Agar was used. The
plates were incubated in anaerobic jars (Oxoid) with Anaerogen (Oxoid) at
37 ∘C for 48 h (Proietti et al., 2008).
Bacterial colony forming units (CFU) in the Petri dishes were counted using
a colony counter. The counts were expressed as log10 colony forming
units per gram of digesta (log10 CFU g-1).
Blood biochemical parameters
At the end of experimental period, six chicks (three male and three female)
from each replicate were selected and blood samples were collected from the
wing vein. All the samples were properly labeled and stored for further
studies at -20∘C. The plasma biochemical parameters including
glucose, triglyceride (TG), cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), total protein (TP), and albumin were determined by
a Technicon RA-1000 auto-analyzer (Technicon Instruments Corporation,
Tarrytown, NY, USA) and using the kit package (Pars Azmoon Co Tehran,
Iran). Also, the plasma globulin concentration was determined by the
difference between total protein and albumin (Coles, 1986).
Hematological parameters
Six chicks (three male and three female) from each replicate were selected
on day 42 by collecting blood samples from a wing vein. Blood samples
obtained from all birds were drained into tubes with anticoagulant (EDTA, ethylenediaminetetraacetic acid, 1 mg mL-1 blood). Red-blood-cell (RBC) and white-blood-cell (WBC) counts were
determined by using a hemocytometer according to Natt and Herrick, 1952.
Packed cell volume (PCV) was determined using hematocrit tubes.
The cyanmethemoglobin method as described by Benjamin (1978) was used to
estimate the hemoglobin (Hb).
The effects of using kefir, yogurt, and probiotic on performance of
broiler chickens.
a,b,c Means in rows with same superscript do not differ significantly (P<0.05).
* SEM: standard error of means.
Statistical analysis
Significant differences between mean values were separated by the GLM (general linearized model) procedure of SAS software (2003) and significant differences between
treatments were separated using a Tukey range test at P<0.05.
ResultsPerformance
The effects of kefir, yogurt, and probiotic on BWG, FI, FCR, and EBI of the full rearing period on broiler chickens are shown in Table 3.
The effects of using kefir, yogurt, and probiotic on carcass
characteristics (based on live body weight) in male and female broiler
chickens at 42 d.
a,b,c Means in rows with same superscript do not differ significantly
(P < 0.05).
* SEM: standard error of means.
The results showed that the experimental groups were not significant for effects
on BWG in broilers at 1–10 d. But broiler BWG did differ between the
experimental treatments at 11–24, 25–42, and 1–42 d (P<0.05). The use of 4 % kefir and probiotic in water had higher BWG
than other groups at 11–24 d. Also, at 25–42 d, the use of 4 % kefir
and yogurt in water was significantly higher for BWG compared to 2 % yogurt
and control groups. In addition to the total experimental period, the
treatments containing high levels of kefir, yogurt, and probiotic showed
significantly high BWG than the other groups (P<0.05).
In this study, broiler FI did not differ between the experimental treatments
at 1–10 d but broiler FI in other rearing periods was significantly
affected (P<0.05).
At 11–24, 25–42, and 1–42 d, broilers supplemented with 4 % kefir had
significantly higher FI compared with the control and low supplement levels of kefir and yogurt, which were not different between them. The results showed
that FCR levels were not significantly different between the groups at
different periods except for the second period (11–24 d). According to
results, the use of probiotic at recommended levels was
significantly lower FCR than 2 % yogurt in water (P<0.05).
Also, there were no significant differences in EBI between treatments
during starter, grower, and finisher periods.
Carcass characteristics
The effects of kefir, yogurt, and probiotic on carcass characteristics at 42 d on male and female broiler chickens are shown in Table 4.
The results of this study showed that the carcass yield, thigh yield, and intestine
length in male broilers – also carcass yield, abdominal fat, and intestine
length in female chickens – were significantly affected by treatments (P<0.05). The 4 % kefir supplemented groups in male
broiler chickens presented significantly higher carcass yield and intestine
length compared with the control group (P<0.05). Also, the use of
probiotic at recommended levels in water resulted in higher thigh yield than control
groups in male broiler chickens.
Based on the results obtained from female chickens, it was observed that the
birds under high levels yogurt and kefir treatment had significantly higher
carcass yield compared with the control group (P<0.05). The results
showed that the 4 % supplemented yogurt in water increased intestine
length compared to control groups in the female birds. Also, abdominal fat was
significantly lower (P<0.05) in the probiotic treatments than the
control group.
Gut microbial populations
The effects of kefir, yogurt, and probiotic on gut microbial populations at 24
and 42 d on male and female broiler chickens are shown in Table 5.
The effects of using kefir, yogurt, and probiotic on gut microbial
population in male and female broiler chickens at 25 and 42 d.
TraitsTreatments ControlProbiotic2 %4 %2 %4 %SEM*P valuePrimaLacyogurtyogurtkefirkefirMale gut microbial population at 25 d Coliform bacteria (log CFU g-1)4.08ab3.44b4.15a3.76ab4.13a3.79ab0.150.0176Lactobacillus (log CFU g-1)5.06c6.02ab5.36cb5.87ab5.02c6.03a0.140.0001Total bacteria (log CFU g-1)6.665.776.295.976.095.460.300.1448Female gut microbial population at 25 d Coliform bacteria (log CFU g-1)4.19a3.54ab4.12ab3.51b3.97ab3.53ab0.150.0077Lactobacillus (log CFU g-1)5.17b6.06a5.61ab6.01a5.82ab6.09a0.160.0157Total bacteria (log CFU g-1)6.256.126.146.086.116.060.170.9823Male gut microbial population at 42 d Coliform bacteria (log CFU g-1)6.20ab5.59ab6.47a5.75ab6.14ab5.08b0.280.0313Lactobacillus (log CFU g-1)5.93b7.05a5.84b6.58ab6.23ab7.09a0.220.0022Total bacteria (log CFU g-1)7.276.476.856.407.096.530.550.8296Female gut microbial population at 42 d Coliform bacteria (log CFU g-1)5.98a5.08b5.80a5.23b5.92a5.17b0.060.0001Lactobacillus (log CFU g-1)6.73b7.09ab6.81ab7.11a6.73b7.12a0.070.0025Total bacteria (log CFU g-1)7.076.516.986.016.966.770.370.3679
a,b,c Means in rows with same superscript do not differ significantly
(P<0.05).
* SEM: standard error of means.
These results indicate that treatments had an effect on lactobacilli and coliform
bacteria populations in male and female broiler chickens at 25 and 42 d
(P<0.05). In male broiler chickens, the coliform bacteria
population decreased in the group treated with probiotic compared with
broilers supplemented with 2 % yogurt and kefir in water. Also, the use of
4 % yogurt in water decreased coliform bacteria population in female
broiler chickens at 25 d.
A significant increase in lactobacilli population was observed in
the male broiler chickens that received high levels of kefir, yogurt, and probiotic at recommended levels compared with the control group (P<0.05).
Additionally, the results of this study showed that the supplement of 4 %
kefir in female broiler chickens significantly increased lactobacilli population at 25 d (P<0.05). At 42 d the results
indicated that supplemented 4 % kefir in water in male broiler chickens
and 4 % kefir and yogurt and probiotic at recommended levels in female
broiler chickens caused a decrease in coliform bacteria population. The
supplement of 4 % kefir and probiotic at recommended levels in water
significantly increased lactobacilli population at 42 d in male
broiler chickens (P<0.05). Also, female broilers that received higher
kefir and yogurt levels had higher lactobacilli population compared
with 2 % kefir and control groups that were not different between them.
Blood biochemical parameter
The effects of kefir, yogurt, and probiotic in water on blood biochemical
parameters at 42 d on male and female broiler chickens are shown in Table 6.
The effects of using kefir, yogurt, and probiotic on blood
biochemical parameters in male and female broiler chickens at 42 d.
TraitsTreatments ControlProbiotic2 %4 %2 %4 %SEM*P valuePrimaLacyogurtyogurtkefirkefirMale blood biochemical parameters at 42 d Glucose (mg dL-1)205.75b226.50a209.25ab228.75a223.25ab221.00ab4.350.0070Cholesterol (mg dL-1)120.00a107.25ab117.00ab105.25b107.75ab104.25b3.050.0068Triglyceride (mg dL-1)25.5021.2523.2524.2525.2523.251.470.3801LDL2 (mg dL-1)35.6133.2535.7332.6231.7530.241.060.3360HDL3 (mg dL-1)75.4369.2574.5071.1473.0070.523.160.7419Total protein (g dL-1)5.06ab5.55ab4.95b5.68ab5.13ab6.37a0.310.0412Albumin (g dL-1)2.703.293.133.183.133.230.220.4884Globulin (g dL-1)2.362.261.822.502.003.140.330.1430Female blood biochemical parameters at 42 d Glucose (mg dL-1)209.50b221.25ab218.75ab221.75a219.25ab222.25a2.650.0317Cholesterol (mg dL-1)123.75a114.75ab123.50a112.75b117.25ab112.75b2.010.0015Triglyceride (mg dL-1)26.0023.5026.7520.5026.2523.502.120.3276LDL (mg dL-1)37.00a31.50b36.50a34.50ab34.25ab33.75ab1.050.0208HDL (mg dL-1)79.1278.2579.4975.7779.4575.231.350.1358Total protein (g dL-1)5.085.534.995.935.155.920.320.3314Albumin (g dL-1)2.972.843.273.393.273.500.210.4735Globulin (g dL-1)2.112.691.722.541.882.450.410.5071
a,b,c Means in rows with same superscript do not differ significantly
(P<0.05).
1 SEM: standard error of means.
2 LDL: low-density lipoprotein.
3 HDL: high-density lipoprotein.
Blood glucose, cholesterol, and total protein concentrations in male broiler
chickens were affected by treatments. Additionally, the treatments had an
effect on blood glucose, cholesterol, and LDL concentrations in female broiler
chickens (P<0.05). These results indicate that the supplementation with
4 % yogurt in male broiler chickens had higher blood glucose
concentration compared with the control group. Also, the use of high levels
of kefir and yogurt in water decreased blood cholesterol concentration than the
control group in male broilers. The results of total protein showed a
significant difference between treatment and control groups (P<0.05). The total protein concentration was significantly increased by the
use of high levels of kefir in water compared with the control group in the
male broilers (P<0.05).
In this experiment, the blood glucose concentration significantly increased
with the addition of 4 % kefir and yogurt in the water (P<0.05).
Also, the use of higher levels of kefir, yogurt, and probiotic at recommended
levels in water resulted in significantly decreased blood cholesterol concentrations
in female broiler chickens (P<0.05). Additionally, the utilization of
probiotic at recommended levels in water resulted in significantly decreased
blood LDL concentrations in female broiler chickens (P<0.05).
Blood hematological parameter
The effects of different levels of kefir, yogurt, and probiotic in the water
on blood hematological parameters at 42 d on male and female broiler
chickens are shown in Table 7.
The effects of using kefir, yogurt, and probiotic on hematological
parameters in male and female broiler chickens at 42 d.
TraitsTreatments ControlProbiotic2 %4 %2 %4 %SEM*P valuePrimaLacyogurtyogurtkefirkefirMale hematological parameters at 42 d White blood cell (×103µL-1)22.0521.9720.9721.9020.7521.900.850.8106Red blood cell (×106µL-1)3.082.982.752.782.752.710.420.9842Hemoglobin (g dL-1)8.129.478.279.008.378.950.460.3206Packed cell volume (%)29.5029.7528.2529.2529.7529.251.260.9605Female hematological parameters at 42 d White blood cell (×103µL-1)21.6521.9521.3722.0020.8721.300.450.5302Red blood cell (×106µL-1)2.402.072.292.312.212.490.270.8859Hemoglobin (g dL-1)7.907.558.207.327.708.220.610.8754Packed cell volume (%)28.2527.7526.7528.0026.0026.500.940.4727
a,b,c Means in rows with same superscript do not differ significantly (P<0.05).
* SEM, standard error of means.
By examining the results, it can be concluded that the use of
different levels of kefir, yogurt, and probiotic in water did not
significantly affect WBC counts, total RBC count, PCV, and Hb at the end
of the experiment.
Discussion
By examining the results obtained, it can be concluded that the use of 4 %
kefir improved the BWG and FI of broiler chicks. In a similar study,
Toghyani et al. (2015) reported that the use of 2 % kefir increased BWG
and FI in broiler chickens. Also, in another experiment, Cenesiz et al. (2008)
indicated that supplemented 7.5 % kefir increased BWG in broiler chickens.
In general, the results of this study showed that using high levels of kefir
in water can improve performance of broiler chickens; therefore, it can be
stated that kefir is a natural product that contains some compounds like
lactic acid bacteria and yeast (Farnworth, 2005). Therefore this product has
been reported to have probiotic activity and can improve the performance
of broiler chickens (Toghyani et al., 2015). Cho et al. (2013) demonstrated
that broilers supplemented with 0.1 % fermented milk kefir in diets had
significantly higher body weight at the end of the experiment compared to control groups. Kefir
is a natural product containing a complex mixture of lactic acid bacteria and
yeasts, which have been reported to be probiotics (Fuller, 1989; Toghyaniet
al., 2015). Also, based on our experiments, we found that the use of 4 %
yogurt in water improved BWG compared to 2 % kefir, yogurt, and control
group in broiler chickens. Similarity, Boostani et al. (2013) and Khan et
al. (2011) stated that the use of yogurt in water improved the BWG, FI,
and FCR of broiler chickens. Sultan et al. (2006) reported that the use of 5 mL-1 yogurt in water increased BWG compared to control group and low
yogurt level. Boostani et al. (2013) indicated that a higher Lactobacillus population in
yogurt increase BWG and FI in broiler chickens. Additionally, this researcher
states that the high BWG of broilers fed yogurt was related to the lactobacilli population in yogurt. Also, by improving intestinal microbial balance,
probiotics beneficially influence growth performance. Significant
improvement in the BWG and FCR obtained in this study supports the results
of others (Lan et al., 2003; Panda et al., 2006) that probiotics improve
broiler performance. Probiotics can also improve broiler performance by
increasing the villous height in the small intestine (Gunal et al., 2006;
Panda et al., 2006). Talebi et al. (2008) demonstrated that the use of
probiotic (PrimaLac) in diets increased BWG in broiler chickens. Generally,
according to the results, it seems that the use of 4 % kefir, yogurt, and
probiotic at recommended levels can increase beneficial bacteria as well as
decrease pathogenic bacteria in the intestine, which can enhance intestine
health and also improve digestion and absorption. In a similar case,
researchers have stated that probiotics can improve gut-beneficial
microorganisms by inhibiting the growth of pathogens, and consequently cause
better digestion and absorption of nutrients (Jin et al., 2000; Toghyani et
al., 2015). In this research, the high BWG and FI have been related to some
benefits derived from enzymes of lactobacilli and high digestion of food. Furthermore,
probiotic compounds increase the metabolizable energy by increasing the
digestibility of carbohydrates due to increasing the activity of the amylase
enzyme. In addition, probiotics can cause a reduction in the activity of
harmful enzymes such as urease and glycosidase (beta-glucuronidase and
beta-glucosidase), which disturb the digestive tract of the bird (Jin et
al., 2000).
Regarding the data, it can be concluded that the use of 4 %
kefir in water improved carcass yield in male and female broiler chickens at
the end of the experiment. Other related studies included projects by Toghyani
et al. (2015), who reported that the use of 2 % kefir in the water had
no significant effect on carcass yield in broiler chickens. It has been
previously reported that kefir grains contained some strains of the lactobacilli and yeasts and have already been described to be probiotics. Also they are
used in probiotic preparations (Fuller, 1989). Therefore, supplementing of kefir including
Lactobacillus bacteria into broiler water or diet caused an increase in the live
body weight (Cho et al., 2013). The results of this research were in
agreement with findings of other authors (Sultan et al., 2006), who reported
that the use of probiotic products improved the carcass characteristics of
broiler chickens. Moreover, Khaliq and Ebrahimnezhad (2016) concluded that
the use of probiotic at total experimental period increased carcass yield of
broiler chickens. It seems that the higher carcass yield in kefir treatment
in this study is related to the high BWG at end of the experimental period.
Also, the researchers stated that the high carcass yield was probably due to
the probiotic effects on the secretion of compounds such as organic acids
that improved nutrient metabolism and increased carcass yields (Ahangari et
al., 2013). It was observed that the supplementation of 4 % kefir and 4 %
yogurt in water increased the length of the intestine in male and female
broiler chickens. Therefore, it seems that the higher intestine length in
this study probably related to receiving probiotic compounds like
lactobacilli and yeast that improves digestion and absorption processes in the
intestine of the broiler chickens. In a similar case, Tsirtsikos et al. (2012) reported that the use of probiotic in diet improved intestinal
conditions. In contrast with our results, Toghyani et al. (2015) reported
that the use of kefir in diet decreased the length of intestine in broiler
chickens. In addition, this study results showed that the use of probiotic
at recommended levels in water decreased abdominal fat in female broiler
chickens. Similarly, Yusrizal and Chen (2003) and Paryad and Mahmoudi (2008)
reported that supplementation of probiotic had produced a low level of
abdominal fat in broiler chickens. Hence, it seems that the use of probiotic
increased digestion and absorption due to higher intestinal microbial
population and gut health, and the balance of absorbed nutrients has increased
and caused decreasing abdominal fat. Concluding the same result, other
researchers reported that the use of probiotic decreased abdominal fat in
broiler chickens (Khan et al., 2011; Boostani et al., 2013). In addition,
low abdominal fat in this study can be related to low acetyl-CoA
carboxylase, which is one of the important enzymes to fatty acid synthesis
(Santoso et al., 1995).
The results of this study indicate that the use of 4 % kefir in water increased lactobacilli population in male and female broiler chickens at 25
and 42 d. Also, the use of 4 % kefir in water decreased coliform
bacteria population in male and female broiler chickens at 42 d. In the same
case, Yaman et al. (2006) demonstrated that the use of kefir increased lactobacilli population and decreased coliform bacteria population in
intestine microflora. On the other hand, the results of this experiment showed
that the use of 4 % yogurt increased lactobacilli and decreased coliform
bacteria in female broiler chickens at 25 and 42 d. Similarity, Boostani
et al. (2013) state that the supplementation of yogurt in water decreased
Escherichia coli and Clostridium perfringens bacteria in broiler chickens. Based on our experiments, we found that
the probiotic supplementation at recommended levels increased lactobacilli
population in female chickens at 25 d and male broiler chickens at 42 d.
While the use of probiotic decreased coliform bacteria in male chickens at
25 d and female chickens at 42 d. The results of this research were in
agreement with findings of other authors (Khaliq and Ebrahimnezhad, 2016)
showing that the use of lactobacilli sources as probiotic increased lactobacilli population
and decreased coliform bacteria population in the intestine of broiler
chickens. Generally, it seems that kefir, yogurt, and probiotic, having
a beneficial microbial population such as lactobacilli, reduce
the intestinal pH in the bird, and the intestinal environment becomes
inappropriate for the proliferation of pathogens and therefore
reduces the harmful microbial population in the intestine. Also, the
researchers reported that reduction of coliform bacteria population in the
intestine can be attributed to the production of lactic acid and acetic acid
and other compounds from microorganisms imported through probiotic
supplements into the intestine, which inhibit pathogenic bacterial growth and
helps beneficial bacteria to adhere and rapidly colonize the intestinal
mucosa of the animal (Fuller, 1989). In addition, it should be noted that
the presence of yeast in kefir and yogurt has reduced the population of
coliform bacteria in the intestine. Similarly, Hassanein and Soliman (2010)
showed that the use of Saccharomyces cerevisiae decreased coliform bacteria population in broiler
chickens. Lin et al. (2011) reported that supplementation of probiotics
decreased E. coli population in controlled groups of ducks. Other similar studies
included projects by Khaliq and Ebrahimnezhad (2016) and Yaman et al. (2006),
who showed that the supplementation of probiotics increased lactobacilli
population in broiler chickens. Furthermore, Lactobacillus bacteria may play an important
role in preventing the growth of harmful bacteria in the digestive tract of
birds (Fuller, 1989). It seems that the use of probiotics and fermented milk
products can increase the Lactobacillus bacteria population in the intestine of broiler
chickens (Yaman et al., 2006; Khaliq and Ebrahinezhad, 2016; Jin et al.,
1998a).
In the present study, the usage of high levels of kefir has been shown to
increase blood glucose concentration in female broiler chickens. Also, the
supplementation of 4 % yogurt in water increased blood glucose
concentration in male and female broiler chickens. Moreover, the probiotic
treatment showed higher blood glucose concentration in male broiler
chickens. For this purpose, the researchers showed that using probiotic
supplements can increase blood glucose levels. In the same results,
Ghasemi-Sadabadi et al. (2016) reported that the use of probiotics from 1 to
42 d increased blood glucose concentration in broiler chicks. In another
experiment, however, Pourakbari et al. (2016) observed that the probiotic had no
significant effect on blood glucose concentration. Increasing blood glucose
concentration in this study may be related to the increased absorption of
nutrients from the intestinal mucosa due to histomorphological changes in
the intestine (Awad et al., 2009). Also, the high glucose level can be
related to digestion of nutrients due to intestine enzymes (Mountzouris et
al., 2007; Jin et al., 2000). The results of this study showed that use of
4 % kefir in water decreased blood cholesterol concentration in male and
female broiler chickens. Toghyani et al. (2015) reported that the use of
kefir in water decreased blood total cholesterol in broiler chickens.
Furthermore, Cenesiz et al. (2008) demonstrated that milk kefir had a
significantly lower total lipid and cholesterol in broiler chickens.
Furthermore, some scientists (Brashears et al., 1998) suggested that reduced
blood cholesterol concentration induced by kefir could be attributed to the
deconjugation of bile acids by Lactobacillus spp. Also, in this experiment low blood
cholesterol concentration was observed by treating with 4 % yogurt in water.
Similarity, Khan et al. (2011) indicated that the use of yogurt in water
decreased blood cholesterol concentration in broiler chickens. Haque et al. (2017) observed that the use of yogurt in water had significantly lower
blood cholesterol concentration than commercial probiotic and control group.
Overall, our results are in agreement with other researchers
(Ghasemi-Sadabadi et al., 2016; Pourakbari et al., 2016; El-Rahman et al.,
2012; Kalavathy et al., 2003). These researchers reported that the
supplementation of probiotic compounds decreased blood cholesterol in broiler
chickens. Also, it is hypothesized that some bacterial probiotic strains are
able to incorporate cholesterol into the bacterial cells, hydrolyze bile
salts, or inhibit hydroxymethylglutaryl-CoA, the rate-limiting enzyme of
cholesterogenesis, thus reducing cholesterol in the body pool (Kalavathy et
al., 2003). Similarly, results from other research state that Lactobacillus and
bifidobacteria could contribute to the regulation of blood cholesterol concentrations by
the conjunction of bile acids. Since the excretion of deconjugated bile
acids was enhanced and cholesterol plays a role as its precursor, more molecules
are spent for recovery of bile acids (Ghasemi-Sadabadi et al., 2016; Pereira
and Gibson, 2002). Also, regarding the data, it can be concluded that
supplementation of probiotic in water reduced blood LDL concentration in
female broiler chickens. Kalavathy et al. (2003) and Pourakbari et al. (2016) demonstrated that the use of probiotic decreased the blood LDL
concentration in broiler chickens. Fukushima and Nakano (1995) observed an
improvement in the serum HDL and decline in blood LDL and cholesterol with probiotic. The blood LDL concentration decrease might be due to
anorexia or defective lipid metabolism (Ghasemi-Sadabadi et al., 2010).
Also, 60 % to 70 % change in plasma cholesterol directly affected
blood LDL (Fischbach, 2004). The hypercholesterolemia effects of
probiotic can be attributed to the compounds of Aspergillus oryzae that are known to inhibit
biosynthesis of cholesterol (Hajjaj et al., 2005). Also, the
hypercholesterolemia effect of Aspergillus oryzae can be related to the association with a key
enzyme as hydroxy-3-methylglutaryl coenzyme A-3 in the synthesis of
cholesterol in chickens (Lee et al., 2006). In the present study, the results
showed that the use of 4 % kefir in water increased blood total protein
concentration compared to 2 % yogurt in male chickens. As previous research
stated that kefir as a fermented milk product has a probiotic role,
research indicates that kefir products contain a complex mixture of
beneficial bacteria; therefore, it includes advantageous effects like a
probiotic (Cho et al., 2013). Hence, high blood total protein concentration
in 4 % kefir in water may be related to the high Saccharomyces cerevisiae in kefir compared to
yogurt. The same studies (Paryad and Mahmoudi, 2008) showed that the use of
higher Saccharomyces cerevisiae increased blood total protein concentration in broiler chickens.
Also, El-Rahman et al. (2012) stated that supplementation of probiotic
increased blood total protein concentration. Arslan and Saatci (2004) showed
that the use of probiotic in water improved blood protein concentration in
quail. In contrast to this study, researchers found that blood total
protein concentration was not affected in broilers that were given probiotic
(Toghyani et al., 2015).
The results of this research showed that the use of different levels of
kefir, yogurt, and probiotic in water did not significantly affect
hematological parameters at the end of the experiment. The results of this
research were in agreement with findings of other authors (Cho et al., 2013;
Al-Saad et al., 2014; Khan et al., 2011) showing that WBC counts, RBC
counts, PCV, and Hb were not affected by supplementation of probiotic
products, This inconsistency among research reports may be related to
differences in probiotic types or number of bacterial species present in
probiotic products (Al-Saad et al., 2014). Conversely, probiotics lowered
lymphocytes and neutrophil values when compared to the control (Owosibo et
al., 2013).
Conclusions
The results of the present study showed that the use of 4 % kefir,
yogurt, and probiotic at recommended levels in water had beneficial effects
on the growth performance, intestinal bacteria population, and blood
biochemical parameters in male and female broiler chickens. Consequently,
these experimental results showed that 4 % kefir and yogurt, as kinds of
fermented milk products, can be considered synthetic growth-promoter-like
commercial probiotics in broiler chickens.
Author contributions
YE and MGS designed and coordinated
the experiment and prepared the article. Also, MGS,
VBG, and HK carried out the experiment and
helped to prepare the article. AST participated in the
design of the study and helped to modify the article. MD
prepared kefir and yogurt and analyzed the chemical and microbiological
characteristics of kefir and yogurt.
Competing interests
The authors declare that they have no conflict of interest.
Acknowledgements
The authors would like to thank project supervisors Yahya Ebrahimnezhad. Thanks also to Siamak Khazaei-Sarcheshmeh for editing the English of this article. Moreover, thanks to Parla Bannay-Zirakkar for help with measurements of blood hematological parameters in this study. Furthermore, thanks to Seyed Amir Seyed Moslemi
(PhD student, Department of Food Science and Technology, Faculty of
Agriculture, University of Tabriz, Tabriz, Iran) for his kind help with this
study.
Review statement
This paper was edited by Manfred Mielenz and reviewed by two anonymous referees.
References
Ahangari, Y. J., Kavan, B. P., and Hoseinzadeh, M.: The effect of probiotic
on performance and immunity parameters of broilers, Research on Animal
Production, 4, 46–56, 2013 (in Persian).Alirezalu, K., Hesari, J., Azadmard-Damirchi, S., Farajnia, S., and
Fathi-Achachlouei, B.: Evaluation of chemical and microbiological properties
of concentrated “Tuluq” and “Torba” yoghurts during storage, JFST, 13,
37–47, available at: http://journals.modares.ac.ir/article-7-9206-en.html (last access: 20 June 2019), 2016 (in Persian).Al-Saad, S., Abbod, M., and Abo Yones, A.: Effects of some growth promoters
on blood hematology and blood composition of broiler chickens, Int. J.
Agric. Res. 9, 265–270, 10.3923/ijar.2014.265.270, 2014.Apata, D. F.: Antibiotic resistance in poultry, Inter. J. Poult. Sci., 8,
404–408, 10.3923/ijps.2009.404.408, 2009.
Arslan, C. and Saatci, M.: Effects of probiotic administration either as feed
additive or by drinking water on performance and blood parameters of
Japanese quail, Arch, Geflügelkd., 68, 160–163, 2004.Awad, W.
A., Ghareeb, K., Abdel-Raheem, S., and Böhm, J.: Effects of dietary
inclusion of probiotic and synbiotic on growth performance, organ weights,
and intestinal histomorphology of broiler chickens, Poult. Sci., 88, 49–56,
10.3382/ps.2008-00244, 2009.
Benjamin, M. M.: Outline of veterinary clinical pathology, 3rd Edn., Ames,
IA, the Iowa State University Press, 1978.Boostani, A., MahmoodianFard, H. R., Ashayerizadeh, A., and Aminafshar, M.:
Growth performance, carcass yield and intestinal microflora populations of
broilers fed diets containing Thepax and yogurt, Br. J. Poult. Sci., 15, 1–6,
10.1590/S1516-635X2013000100001, 2013.Brashears, M., Gilliland, S. E., and Buck, L. M.: Bile salt deconjugation
and cholesterol removal from media by Lactobacilluscasei, J. Dairy. Sci., 81, 2103–2110,
10.3168/jds.S0022-0302(98)75785-6, 1998.Cenesiz, S., Yaman, H., Ozcan, A., Kart, A., and Karademir, G.: Effects of
kefir as a probiotic on serum cholesterol, total lipid, Aspartate amino
transferase and alanine amino transferase activities in broiler chicks, Med.
Weter., 64, 168–170, available at: http://www.medycynawet.edu.pl/129-summary-2008/summary-2008-2/705-summary-edycyna-wet-64-2-168-170-2008
(last access: 20 June 2019),
2008.Cho, J. H., Zhang, Z. F., and Kim, I. H.: Effects of single or combined
dietary supplementation of b-glucan and kefir on growth performance, blood
characteristics and meat quality in broilers, Br. Poult. Sci., 54, 216–221,
10.1080/00071668.2013.777691, 2013.
Coles, H. E.: Veterinary clinical pathology, 4th Edn., W.B. Saunders Co.,
USA, Philadelphia, 1986.Denli, M., Okan, F., and Celi, K.: Effect of dietary probiotic, organic acid
and antibiotic supplementation to diets on broiler performance and carcass
yield, Pakistan. J. Nutr., 2, 89–91, 10.3923/pjn.2003.89.91, 2003.El-Rahman, A. H. A., Kamel, H. H., Ahmed, W. M., Mogoda, O. S. H., and
Mohamed, A. H.: Effect of Bactocell® and Revitilyte-plustm as probiotic food supplements
on the growth performance, hematological, biochemical parameters and humoral
immune response of broiler chickens, World Appl. Sci. J., 18, 305–316,
2012.
Farnworth, E. R. and Mainville, I.: Kefir: a fermented milk product, in
Hand book of Fermented Functional Foods, edited by: Farnworth, E. R., Boca Raton, FL,
CRC Press, 2003.Farnworth, E. R.: Kefir – a complex probiotic, Food. Sci. Tech. Bull. Funct.
Foods., 2, 1–17, 10.1616/1476-2137.13938, 2005.
Fischbach, F. A.: Manual of laboratory and diafnostic test, 8 Edn., Lippincott
Williams and Wilkins, Philadelphia, USA, 2004.Fukushima, M. and Nakano, M.: The effect of a probiotic on faecal and liver
lipid classes in rats, Br. J. Nutr., 73, 701–710,
10.1079/BJN19950074, 1995.Fuller, R.: Probiotics in man and animals, J. Appl. Bacteriol., 66, 365–378,
10.1111/j.1365-2672.1989.tb05105.x, 1989.
Fuller, R.: Probiotics for farm animals. In Probiotics: A Critical Review,
edited by: Tannock, G. W., Horizon scientific press, Wymondham, UK, 15–22, 1998.Ghasemi-Sadabadi, M., Ebrahimnezhad, Y., and Khaliq, M.: The effects of
Yeasture® at different rearing stages on intestinal microflora and
blood biochemical parameters in male and female broiler chickens, Res. Opin. Anim. Vet. Sci., 6, 144–150, 10.20490/ROAVS/16-026, 2016.Gunal, M., Yayli, G., Kaya, O., Karahan, N., and Sulak, O.: The effects of
antibiotic growth promoter, probiotic or organic acid supplementation on
performance, intestinal microflora and tissue of broilers, Inter. J. Poult.
Sci., 5, 149–155, 10.3923/ijps.2006.149.155, 2006.Hajjaj, H., Duboc P., Fay, L. B., Zbinden, I., Mace, K., and Niederberger,
P.: Aspergillus Oryzae producs compounds inhibiting cholesterol biosynthesis downstream of
dihydrolanosterol, FEMS. Microbiol. Lett., 242, 155–159,
10.1016/j.femsle.2004.11.001, 2005.Haque, M. D. I., Ahmad, N., and Miah, M. A.: Comparative analysis of body
weight and serum biochemistry in broilers supplemented with some selected
probiotics and antibiotic growth promoters, J. Adv. Vet. Anim. Res., 4,
288–294, 10.5455/javar.2017.d226, 2017.Hassanein, S. M. and Soliman, N. K.: Effect of probiotic (Saccharomyces cerevisiae) adding to diets
on intestinal microflora and performance of Hy-line layer hens, J. Am. Sci.,
6, 159–69, available at: https://www.researchgate.net/publication/268199840 (last access: 12 May 2018), 2010.Irigoyen, A., Arana, I., Castiella, M., Torre, P., and Ibanez, F. C.:
Microbiological, physicochemical, and sensory characteristics of kefir
during storage, Food, Chem., 90, 613–620,
10.1016/j.foodchem.2004.04.021, 2005.Itsaranuwat, P., Al-Haddad, K. S. H., and Robinson, R. K.: The potential
therapeutic benefits of consuming “health promoting” fermented dairy
products: a brief update, Int. J. Dairy. Technol., 56, 203–210,
10.1046/j.1471-0307.2003.00106.x, 2003.Jin, L. Z., Ho, Y. W., Abdullah, N., Ali, A. M., and Jalaludin, S.: Effects
of adherent Lactobacillus cultures on growth, weight of organs and
intestinal microflora and volatile fatty acids in broilers, Anim. Feed. Sci.
Tech., 70, 197–209, 10.1016/S0377-8401(97)00080-1, 1998a.Jin, L. Z., Ho, Y. W., Abdullah, N., and Jalaludin, S.: Growth performance,
intestinal microbial populations, and blood cholesterol of broilers fed
diets containing Lactobacillus cultures, Poult. Sci., 77, 1259–1265, 10.1093/ps/77.9.1259, 1998b.Jin, L. Z., Ho, Y. W., Abdullah, N., and Jalaludin, S.: Digestive and
bacterial enzyme activities in broilers fed diets supplemented with
Lactobacillus cultures, Poult. Sci., 79, 886–891, 10.1093/ps/79.6.886, 2000.Kabir, S. M. L., Rahman, M. M., Rahman, M. B., Rahman, M. M., and Ahmed, S.
U.: The dynamics of probiotics on growth performance and immune response in
broilers, Int. J. Poult. Sci., 3, 361–364,
10.3923/ijps.2004.361.364, 2004.Kalavathy, R., Abdullah, N., Jalaludin, S., and Ho, Y. W.: Effects of
Lactobacillus cultures on growth performance, abdominal fat deposition, blood lipids and
weight of organs of broiler chickens, Br. Poult. Sci., 44, 139–144, 10.1080/0007166031000085445, 2003.Kang, H. K., Salim, H. M., Akter, N., Kim, D. W., Kim, J. H., Bang, H.
T., Kim, M. J., Na, J. C., Hwangbo, J., Choi, H. C., and Suh, O. S.: Effect
of various forms of dietary chlorella supplementation on growth performance,
immune characteristics, and intestinal. microflora population of broiler
chickens, J. Appl. Poult. Res., 22, 100–108,
10.3382/japr.2012-00622, 2013.Khaliq, M. and Ebrahimnezhad, Y.: The effects of probiotic
Yeasture® using at different rearing periods on performance,
intestinal microbial population and carcass traits in broiler chickens, Vet.
Sci. Dev., 6, 61–70, 10.4081/vsd.2016.6170, 2016.Khan, S. H., Burhan, Y., Mian, A. A., Rehman, A., and Farooq, M. S.:
Assessing the effect of administering different probiotics in drinking water
supplement on broiler performance, blood biochemistry and immune response,
J. Appl. Anim. Res., 39, 418–428, 10.1080/09712119.2011.623783, 2011.Lan, P. T., Binh, T. L., and Benno, Y.: Impact of two probiotics
Lactobacillus strains feeding on fecal Lactobacilli and weight gains in chickens, J. Gen.
Appl. Microbiol., 49, 29–36, 10.2323/jgam.49.29,
2003.Lee, K., Lee, S. K., and Lee, B. D.: Aspergillus oryzae as probiotic in poultry-a review, Int.
J. Poult. Sci., 5, 1–3, 10.3923/ijps.2006.1.3, 2006.Lin, S. Y., Hung, A. T. Y., and Lu, J. J.: Effects of supplement with
different level of Bacillus coagulans as probiotic on growth performance and intestinal
microflora populations of broiler chickens, J. Anim. Vet. Adv., 10, 111–114,
10.3923/javaa.2011.111.114, 2011.
Magalhaes, K. T., Pereira, G. V. M., Campos, C. R., Dragone, G., and Schwan,
R. F.: Brazilian kefir: structure, microbial communities and chemical
composition, Braz. J. Microbiol., 42, 693–702,
doi.org/10.1590/S1517-83822011000200034, 2011.Maity, T. K., Kumar, R., and Misra, A. K.: Development of healthy whey
drink with Lactobacillus rhamnosus, Bifidobacterium bifidum and Propionibacterium freudenreichii subsp, Shermanii. Mljekarstvo., 58, 315–325, https://hrcak.srce.hr/30635 (last access: 9 March 2017), 2008.
Marshall, T. R.: Standard methods for the examination of dairy products,
16th Edn., Washington, DC, USA, American Public Health
Association, 363–536, 2005.
Metchnikoff, E.: The prolongation of life, 1st Edn., New York, GP Putman
Sons., 1998.Mountzouris, K. C., Tsistsikos, P., Kalamara, E., Nitsh, S., Schatzmayr, G.,
and Fegeros, K.: Evaluation of the efficacy of a probiotic containing
Lactobacillus, Bifidobacterium, Enterococcus, and Pediococcus strains in promoting broiler performance and modualting cecal
microflora composition and metabolic activities, Poult. Sci., 86, 309–317,
10.1093/ps/86.2.309, 2007.Natt, M. P. and Herrick, C. A.: A new blood diluent for counting the
erythrocytes and leucocytes of the chicken, Poult. Sci., 31, 735–737,
10.3382/ps.0310735, 1952.Nergiz, C. and Seckin, A. K.: The losses of nutrients during the production
of strained (Torba) yoghurt, Food. Chem., 61, 13–16, 10.1016/S0308-8146(97)00147-7, 1998.
NRC: Nutrient requirements of poultry, 9th National Research Council,
Washington, D.C National Academy Press, 1994.Otles, S. and Cagindi, O.: Kefir: a probiotic dairy-composition, nutritional and therapeutic aspects, Pak. J. Nutr., 2, 54–59, 10.3923/pjn.2003.54.59, 2003.
Owosibo, A. O., Odetola, O. M., Odunsi, O. O., Adejinmi, O. O., and
Lawrence-Azua, O. O.: Growth, hematology and blood biochemistry of broilers
fed probiotics based diets, African. J. Agric. Res., 8, 5076–5081,
2013.Paryad, A. and Mahmoudi, M.: Effect of different levels of supplemental
yeast (Saccharomyces cerevisiae) on performance, blood constituents and carcass characteristics of
broiler chicks, Afr. J. Agric. Res., 3, 835–842,
2008.Panda, A. K., Ramarao, S. V., Raju, M. V. L. N., and Sharma, S. R.: Dietary
supplementation of probiotic Lactobacillus sporogenes on performance and serum
biochemico-lipid profile of broiler chickens, J. Poult. Sci, 43,
235–240, 10.2141/jpsa.43.235, 2006.Pelczar, M. J., Chan, E. C. S., and Krieg, N. R.: Microbiology, Mc
Graw-Hill, Inc. New York, 1986.
Pereira, D. I. A. and Gibson, G. R.: Cholesterol assimilation by lactic
acid bacteria and Bifidobacteria isolated from the human gut, Appl. Environ. Microb.,
68, 4689–4693, 10.1128/AEM.68.9.4689-4693.2002, 2002.Pourakbari, M., Seidavi, A., Asadpour, L., and Martínez, A.: Probiotic
level effects on growth performance, carcass traits, blood parameters, cecal
microbiota, and immune response of broilers, An. Acad. Bras. Ciênc., 88,
1011–1021, 10.1590/0001-3765201620150071, 2016.Prado, M. R., Blandón, L. M., Vandenberghe, L. P., Rodrigues, C.,
Castro, G. R., Thomaz-Soccol, V., and Soccol, C. R.: Milk kefir:
composition, microbial cultures, biological activities, and related
products, Front. Microbiol., 6, 1–10, 10.3389/fmicb.2015.01177, 2015.Proietti, P. C., Bosco, A. D., Hilbert, F., Franciosini, M. P., and
Castellini, C.: Evaluation of intestinal bacterial flora of conventional and
organic broilers using culture-based methods, Ital. J. Anim. Sci., 8, 51–63,
10.4081/ijas.2009.51, 2008.Rosa, D. D., Dias, M. M. S., Grześkowiak, Ł. M., Reis, S. A.,
Conceição, L. L., and Peluzio, M. D. C. G.: Milk kefir: nutritional,
microbiological and health benefits, Nutr. Res. Rev., 30, 82–96, 10.1017/S0954422416000275, 2017.Santoso, U., Tanaka, K., and Ohtani, S.: Effect of dried Bacillus subtilis culture on growth,
body composition and hepatic lipogenic enzyme activity in female broiler
chicks, Br. J. Nutr., 74, 523–529, 10.1079/BJN19950155, 1995.
SAS Institute: SAS Users guide: Statistics. Version 6.12, SAS Institute
Inc., Cary, NC, 2003.Shaddel-Tili, A., Eshratkhah, B., Kouzehgari, H., and Ghasemi-sadabadi, M.:
The effect of different levels of propolis in diets on performance,
gastrointestinal morphology and some blood parameters in broiler chickens,
Bulg. J. Vet. Med., 20, 215–224, 10.15547/bjvm.986, 2017.Sultan, A., Durrani, F. R., Suhail, S. M., Ismail, M., Durrani, Z., and
Chand, N.: Comparative effect of yogurt as probiotic on the performance of
broiler chicks, Pak. J. Biol. Sci., 9, 88–92, 10.3923/pjbs.2006.88.92,
2006.Talebi, A., Amirzadeh, B., Mokhtari, B., and Gahri, H.: Effects of a
multi-strain probiotic (PrimaLac) on performance and antibody responses to
Newcastle disease virus and infectious bursal disease virus vaccination in
broiler chickens, Avian. Pathol., 37, 509–512,
10.1080/03079450802356995, 2008.Toghyani, M., Mosavi, S. K., Modaresi,
M., and Landy, N.: Evaluation of kefir as a potential probiotic on growth
performance, blood biochemistry and immune responses in broiler chicks,
Anim. Nutr., 1, 305–309, 10.1016/j.aninu.2015.11.010, 2015.Tsirtsikos, P., Fegeros, K., Balaskas, C., Kominakis, A., and Mountzouris,
K. C.: Dietary probiotic inclusion level modulates intestinal mucin
composition and mucosal morphology in broilers, Poult. Sci., 91, 1860–1868,
10.3382/ps.2011-02005, 2012.Yaman, H., Ulukanli, Z., Elmali, M., and Unal, Y.: The effect of a fermented
probiotic, the kefir, on intestinal flora of poultry domesticated geese
(Anser anser), Revue. Méd. Vét., 157, 379–386,
2006.
Yusrizal, T. and Chen, T. C.: Effect of adding chicory fructons in feed on
broiler growth performance, serum cholesterol and intestinal length, Int. J.
Poult. Sci., 2, 214–219, 10.3923/ijps.2003.214.219, 2003.
Zulkifli, I., Abdullah, N., Azrin, N. M., and Ho, Y. W.: Growth performance
and immune response of two commercial broiler strains fed diets containing
Lactobacillus cultures and oxytetracycline under heat stress conditions, Br. Poult. Sci.,
41, 593–597, 10.1080/713654979, 2000.