Comparative Study on
Nutritional Components and Egg Quality of Bashang Long Tail Laying Hens in different Feeding Models
Li Chang1,2*, Jiguo Sun1 and Xianglong Li3
1College of Animal Science and Technology, Agricultural University of Hebei
Province, Baoding 071001, Hebei, P. R. China
2Qinhuangdao Animal Disease Control Center, Qinhuangdao 066001, Hebei, P. R.
China
3Hebei Normal University of Science and Technology,
Qinhuangdao 066004, Hebei, P. R. China
*For correspondence: 37837775@qq.com
Received
30 November 2020; Accepted 12 January 2021; Published 16 April 2021
Abstract
In this
research, we made a comprehensive study about the egg quality and nutrient
factors of Bashang long-tailed chickens in different housing systems (in-cage
and free-range). The results showed that: 1) there was no significant
difference in egg weight, egg shape index, egg yolk weight, egg yolk color, egg
yolk ratio, egg white ratio, and Hahn unit between free-range and cage (P
> 0.05). Protein weight,
protein height, eggshell weight, eggshell color and eggshell ratio were
significantly higher in the cage than in free-range (P
< 0.05) and the differences in eggshell weight, eggshell color, and eggshell
ratio were extremely significant (P < 0.01). However, the thickness and strength of eggshell in
free-range breeding were significantly higher than those caged (P
< 0.05). 2) The content of water and crude protein in the eggs of the caged
Bashang long-tail chicken was significantly higher than that of the free-range
chicken (P < 0.05). 3) The content of crude fat content of free-range was significantly
higher than that of caged chickens (P < 0.05), but
there was no significant difference in cholesterol and vitamin A content. 4)
Zinc content of eggs of Bashang long-tail chickens of free-range was
significantly higher than that of caged chickens (P
< 0.05), but there was no significant difference in the content of calcium and
phosphorus. So it’s better than the caged chicken in
the free-range feeding condition, and the free-range feeding is suitable for
the production of Bashang long-tail chicken. This study could be used as a
reference to improve egg quality in the future. © 2021 Friends Science Publishers
Keywords: Bashang long-tail chicken; Cage; Egg quality; Free-range; Nutritional components
Introduction
With
the development of the national economy and the improvement of people's living
standards, people's demand for egg consumption has shifted from quantity to
quality, and more and more attention has been paid to the internal quality of
eggs, and also begin to pay attention to the quality of native eggs, which is
the quality of eggs produced by local chicken breeds (Chang et
al. 2020). Bashang long-tail chicken is the only local
poultry in Hebei Province to be included in the Chinese livestock and poultry
genetic resources list (Tang 2011),
which is an excellent genetic resource of local poultry breeds and belongs to
egg-meat chicken breeds. It lives in the Hebei province of China, mainly in the
Bashang region of Zhang Jiakou and Chengde City (Li et al. 2015; Peng et al. 2019), which is small, strong, active, flexible and mainly
raised by grazing and supplemented with the appropriate amount. It has strong
foraging ability in the wild, rough feed tolerance, cold resistance, disease
resistance, delicious meat, and good egg production performance. The eggshell
of Bashang long-tail chicken is thick, not easy to crack, dark brown, resistant
to the storage and not susceptible to bacterial infection. The yolk is reddish
yellow with a color depth of about 10. It contains high fat. After cooking, its
color, aroma and taste is much better than those of
white or light yellow eggs. The protein is clear, transparent, sticky, and
great taste.
A
study comparing the impact of commercial when housing systems found that hen
management and nutrition have significant impacts on the resulting egg physical
quality (Karcher et al. 2015). Furthermore, the researcher (Jones et
al. 2014) determined that eggs from the conventional cage,
enriched colony cage, and cage-free aviary housing systems declined in egg
quality at a similar rate during extended cold storage (Jones et
al. 2018). To investigate the effect of feeding methods on
the quality of Bashang long-tail chicken eggs, this experiment caged experiment of Bashang long-tail chicken,
compared and analyzed the egg quality and nutrient composition of caged and
free-range eggs, and revealed the characteristics of Bashang long-tail chicken
eggs. The impact of the environment on the quality of the Bashang long-tail
chicken eggs provides a theoretical basis by adopting appropriate feeding
methods. Meanwhile, test data provides a reference for the production and
utilization of Bashang long-tail chicken. It also provides data support for
consumers to correctly understand the nutritional value of eggs, and at the
same time provides a scientific basis for consumers to choose nutrients
rationally and match the diet structure.
Materials and Methods
Experiments
Experimental
materials: In the base group of the Bashang long-tail chicken
breeding core group (Zhangjiakou Jingxingyuan Ecological Agriculture Co.,
Ltd.), 1000 chickens were raised to 42-day-old, and then 500 chickens were
transferred to 12 farmers (Equivalent to 12 replicates) of 5 natural villages
in Changliang Town, Guyuan County, Hebei Province. Each household raises
according to the past free-range feeding model (2 birds/m2, male and
female groups), using local raw grain oatmeal as the main feed material and
naturally stocking them in the farmer's house. The remaining 500 chickens
continue to be semi-open chicken coops and three-dimensional three-story
cages in the Bashang long-tail chicken breeding base of Zhangjiakou
Jingxingyuan Ecological Agriculture Co., Ltd. Feeding, dry powder feed 3 times
a day, free to eat, drink water, daylight 16 h.
Experimental
methods
A
total of 400 fresh eggs (every 200 fresh eggs) were collected from free-range
and caged Bashang long-tail chickens at the peak of egg production (280 days
old), with a laying rate of 70–80%. Two hundred eggs were randomly selected
from each group and analyzed in the laboratory of Hebei Normal University of
science and technology. The remaining 200 eggs (100 free-range eggs and 100
cage eggs) were sent to the Beijing Institute of Nutritional Resources for the
determination and analysis of fatty acids, cholesterol, trace elements, and
other nutrients of Bahang long-tail eggs.
Determination
items and methods of egg quality
Egg
quality was determined by egg weight (EW), egg shape index (ESI), eggshell color
(ESC), eggshell strength (ESS), eggshell weight (ESW), yolk weight (YW),
eggshell thickness (EST), protein height (ah), yolk color (YC), Haugh unit (HU)
(Wang et al. 2012; He et al. 2017, 2019). The
weight of the egg is weighed with an electronic scale (accuracy 0.01 g); the
egg shape index, that is, the ratio of the long diameter to the short diameter
of the egg, is determined by a vernier caliper; the color of the egg shell is
measured by a photoelectric reflection colorimeter; the strength of the egg
shell is measured by the egg shell strength tester (EFR-01, purchased from
Israel ORKA Technology Co., Ltd.); eggshell thickness is measured with an
eggshell thickness tester (ESTG-1, purchased from Israel ORKA Technology Co.,
Ltd.); protein height, force of egg beater or watch glass edge Knock the egg,
put your hand close to the glass plate, carefully pour the egg content down on
the crack on the horizontal glass plate, choose between 2 points between the
edge of the yolk and the edge of the concentrated protein (Zhou et al.
2012); egg weight and egg yolk reuse separation Separate
the egg yolk and the protein, and use the filter paper to dry the protein on
the surface of the egg yolk. Do not damage the egg yolk membrane. Weigh them
separately with an electronic balance; the egg yolk color, Hastelloy unit
multi-function egg quality tester (model EA- 01, purchased from Israel ORKA
Technology Co., Ltd.).
Nutritional chemical
indicators include trace elements such as water, crude protein, crude fat,
cholesterol, Table 1: Comparison on egg quality between
locality layer fed with different feed model
Items |
Cage |
Free-range |
P-value |
Egg weight(g) |
49.37 ± 5.31 |
48.40 ± 7.13 |
0.750 |
Egg shape index (%) |
1.328 ± 0.04 |
1.331 ± 0.06 |
0.805 |
Eggshell weight (g) |
5.989 ± 0.58 |
5.218 ± 0.73 |
0.002 |
Eggshell color (scale) |
32.0 ± 5.65 |
26.4 ± 5.14 |
0.001 |
Eggshell thickness(mm) |
0.25 ± 0.04 |
0.27 ± 0.03 |
< 0.05 |
Eggshell strength (pa) |
4.41 ± 0.68 |
5.736 ± 0.685 |
0.007 |
Yolk weight (g) |
15.23 ± 2.23 |
15.483 ± 2.99 |
0.350 |
Yolk color (scale) |
9.33 ± 0.82 |
9.95 ± 1.19 |
0.250 |
Protein weight (g) |
28.15 ± 3.76 |
27.699 ± 4.49 |
0.045 |
Protein height (mm) |
2.87 ± 0.54 |
2.27 ± 0.60 |
0.031 |
Eggshell ratio (%) |
12.13 ± 1.73 |
10.78 ± 3.045 |
0.001 |
Yolk ratio (%) |
30.85 ± 1.50 |
31.99 ± 3.03 |
0.428 |
Albumen ratio (%) |
57.02 ± 1.96 |
57.23 ± 3.06 |
0.876 |
Haugh unit (Ha) |
50.87 ± 9.34 |
42.02 ± 12.35 |
0.299 |
Notes:
If P < 0.01, it means that the data of the two groups is very
significantly different
If 0.01 < P < 0.05, the data of the two groups
is significantly different
If P > 0.05, it means that there is no significant difference
between the two groups
vitamin
A, zinc, and selenium. After the egg is broken, separate the egg white and yolk
in a petri dish, weigh the egg white and yolk separately and add the total
weight of the petri dish, and place the petri dish in a constant temperature
drying box at 50°C~53°C overnight (Woollard et al.
2016),
Weighing, the difference is even water content (Chun 2016). After the moisture determination, the air-dried
samples were crushed to prepare the standards, and the measurement standards
were based on: moisture "GB/T 5009.3-2016", crude protein "GB/T
5009.5-2016", crude fat "GB/T 5009.6-2016", cholesterol
"GB/T" 37077-2018", vitamin A "GB/T 5009.82-2016",
zinc "GB/T 5009.14-2017", selenium "GB/T 5009.93-2017"
(Zhao et al. 2015).
Results
The
effect of different feeding models on egg quality
From
Table 1,
it can be seen that Bashang long-tail chicken with different feeding models
have no significant difference on the egg weight, egg shape index, egg yolk
weight, egg yolk color, egg yolk ratio, protein ratio, and Haugh unit. The
protein weight and protein height are higher (1.6 and 26.43%) in the cage group
than in the free-range group (P < 0.05). In free-range conditions, egg thickness and eggshell
strength were 8 and 30.07% lower than in caged, respectively (P < 0.05). But, shell weight, eggshell
color, and eggshell ratio was 14.78, 21.2 and 12.52% lower than caged chickens,
respectively, the difference was extremely significant (P < 0.01).
The
effect of different feeding models on nutrients
Comparing
the nutrient composition of Bashang long-tail chicken eggs of different models,
the results showed that the contents of crude protein, elemental selenium and
iron in cage-raised eggs were significantly higher than that in free-range eggs
(P < 0.01); The content of fat
and elemental zinc were significantly lower than that of free-range
eggs, but the moisture content was significantly higher than
that of free-range eggs (P < 0.05);
the differences in the contents of cholesterol, vitamin A, elemental calcium
and phosphorus in cages and free-range eggs were not significant (P > 0.05); the differences in the
contents of Se and Fe were very significant (P < 0.01).
Discussion
Eggshell
quality is one of the important traits in the breeding of laying hens. It not
only affects the hatching rate of breeding eggs but also is related to the
preservation time of eggs and the rate of circulation damage (Liu et al. 2017;
Ji et al. 2018). Eggshell weight, eggshell
thickness, and eggshell strength is important parameters for measuring eggshell
quality (Yang et
al. 2015; Lv et al.
2017). In
this experiment, the eggshell weight of Bashang long-tail chicken eggs of
free-range is significantly lower than that of caged (P < 0.05), but the eggshell thickness Table 2: Comparison on egg nutrients between
locality layer fed with different feed model
Items |
Cage |
Free-range |
P-value |
Moisture/% |
74.28 ± 0.62 |
73.24 ± 0.92 |
0.026 |
Crude protein/% |
13.15 ± 0.29 |
12.37 ± 0.53 |
0.005 |
EE/% |
9.72 ± 0.67 |
10.87 ± 0.85 |
0.012 |
Cholesterol/ (mg/100g) |
419.4 ± 41.8 |
290.8 ± 150.2 |
0.129 |
Vitamin A/ (mg/100g) |
0.22 ± 0.02 |
0.183 ± 0.058 |
0.223 |
Ca (mg/kg) |
307.87 ± 31.32 |
310.010 ± 12.108 |
0.688 |
P (mg/kg) |
95.05 ± 5.280 |
95.890 ± 9.021 |
0.793 |
Zn (mg/kg) |
11.040 ± 4.72 |
16.880 ± 1.300 |
0.042 |
Se (mg/kg) |
1.989 ± 0.92 |
0.091 ± 0.013 |
0.000 |
Fe (mg/kg) |
19.35 ± 8.45 |
2.886 ± 0.169 |
0.000 |
Notes:
If P < 0.01, it means that the data of the two groups is very
significantly different
If 0.01 < P < 0.05, the data of the two groups
is significantly different
If P > 0.05, it means that there is no significant difference
between the two groups
and
eggshell strength are significantly higher than those of caged Bashang
long-tail chickens (P < 0.05)
(Jones et al. 2002) and other studies show that
the higher the strength of eggshell, the lower the breakage rate of eggs during
transportation. The increase in the thickness of the eggshell effectively
prevents pathogens such as bacteria from entering the egg through the eggshell
holes, which is conducive to the preservation of the egg. Therefore, from the
evaluation of eggshell quality, the free-range chicken eggs in this study are
more beneficial to the storage, transportation, and
preservation of eggs than caged eggs. Egg shape index is one of the important
indicators to evaluate egg quality, and an appropriate egg shape index can
reduce the occurrence of egg cracking and breakage. In this experiment, there
was no significant difference in the egg shape index of Bashang long-tail
chicken under different feeding methods, which was consistent with the theory
of breed-related that egg shape depended on the structure of oviduct isthmus and
the physiological state of fallopian tube wall studied by (Huang et
al. 2019);
It is consistent with the research of (Feng 2016)
that the physical traits of eggs are greatly influenced by heredity.
The egg yolk is an important part
of egg nutrition, which concentrates most of the egg nutrition. The proportion
of egg yolk determines the quality of an egg (Wang et al. 2017). This study showed that the
yolk weight, yolk color, and yolk ratio of free-range eggs are slightly higher
than those of caged eggs, but there is no significant difference, indicating
that the nutritional quality of free-range eggs is more abundant than that of
caged eggs.
Haugh units (HU) and protein height are
important indicators for measuring egg freshness, egg quality grading, and international
egg quality testing. The egg
quality grading standard given by the United States Department of Agriculture
is that HU greater than 72 is a special grade, between 60 and 72 is an A grade and between 30 and 60
is a grade B. With the
prolonged storage time, due to protein hydrolysis, the protein concentration
becomes thinner, the protein height decreases and HU becomes smaller. Higher the protein content,
larger the HU and
freshness of the egg. In this
experiment, the protein quality of cage-raised and free-range chickens was all excellent. Due to intensive feeding
management of caged chickens, the quality of eggs is uniform, while the quality
of free-range eggs is uniform. In this experiment, the HU of Bashang long-tail chicken eggs
on caged and free-range are both Grade B, and the difference between free-range
and cage-raised is not significant. However, protein weight and protein height
of caged eggs were
significantly higher than those of free-range eggs. This is because water is
the main component of egg whites and is closely related to the uninterrupted
water supply in cages.
Cholesterol
is an essential substance for human life activities and an important raw
material for the synthesis of bile acid and vitamin D, etc. however, high blood cholesterol content can cause diseases
such as hypertension, atherosclerosis, coronary heart disease, and stroke. Egg
yolk contains a large amount of cholesterol, which is the main source of
exogenous cholesterol intake (Ge et al.
2017). In
the understanding of cholesterol, the public has two distinct and one-sided
views. One view believes that cholesterol is extremely harmful and cannot be
eaten. Another view believes that eating cholesterol in moderation is not only
harmless but also beneficial to health. However, under the current human nutritional
conditions, it is not insufficient cholesterol intake, but access, people
prefer low cholesterol food. As
can be seen from Table 2, the Bashang long-tail chicken eggs in free are 6.82%
lower than that of caged chicken, but the difference was not significant, which
also proved the advantages of free-range.
The
taste of eggs is closely related to their crude fat content and the higher the
crude fat content, the stronger the aroma of eggs (Guo et al. 2007). To sum up, the fat content
of free-range eggs is significantly higher than that of caged eggs (P < 0.05); the crude protein and water
content are significantly lower than those of caged eggs (P < 0.05) and the difference of crude
protein is very significant (P < 0.01). This result which
consistent with the studies of (Anderson 2011) and (Li et al. 2013) that the fat content of
free-range eggs is significantly higher than that of caged eggs, but the water
content was lower.
Vitamin A in eggs, which is commonly found
in egg yolks, is also known as retinol, which is an important element in
maintaining vision and is one of
the most common micronutrients about immunity (Yin 2009; Ginzberg et al. 2000). From Table 2, it can
be seen that the content of vitamin A in free-range chicken eggs was slightly
lower than that of in caged eggs, which also indicated that the content of
vitamin A was related to the way of feeding. All egg quality criteria were not significantly
affected by dietary vitamin A except albumin percentage and Haugh units, since
Haugh unit score was gradually increased with increasing vitamin A level (Zhao et al. 2005). Calcium, iron, and zinc are
indispensable trace elements. Zinc is an important traced element in the growth and
development of young children. It is the key to the growth of human brain
cells, and enhances the body's immune function. Elemental selenium has
antioxidant properties, can enhance the body's immunity, regulate the
absorption of other trace elements, and prevent cancer. Therefore, the content
of selenium in eggs is of great significance to the health of the human diet. The content of
calcium and phosphorus is slightly higher than that caged of eggs, but the
difference is not significant. The level of zinc can improve egg production indices and HU score, so the content of zinc is
significantly higher than that caged of eggs; while the content of selenium and
iron is significantly lower than that of caged eggs.
Conclusion
Poultry is relatively sensitive to the
environment, so it is very important to provide a good environment that is
conducive to the production of laying hens. Healthy farming is main stream
today. Feeding methods of laying hens are roughly divided into the cage and
free-range breeding. Cage breeding is a relatively common breeding mode,
suitable for large-scale breeding with all-in and all-out, good hygienic
conditions and strong controllability of egg quality, which guarantees a high
egg production rate and egg product pass rate. Free-range breeding is mainly a
small-scale group. Chickens eat freely, breed freely, and lay eggs freely. They
have a large active space, little water pollution, and no feed additives. Under
this model, the chicken is delicious, the egg has high nutritional value, and
the flavor has a unique aroma.
People say that domestic firewood eggs have a
strong fragrance and rich nutrition (El-Hack et al. 2017). This test shows that free-range eggs were better than
cage eggs in shell thickness, yolk color, phospholipid content, and lower
cholesterol content in egg yolk. The contents of crude fat, element iron, and
zinc in free-range eggs were significantly higher than those in caged eggs,
while the contents of crude protein, protein height, water and element selenium
in free-range eggs were significantly lower than those in caged eggs. This is
consistent with the studies of Zhao Chao and Yin Ruoxin, that free-range
chickens can produce eggs with better yolk color, higher phospholipid content
and lower yolk biliary solids content than caged chickens.
Our study was the first to compare the egg quality
and nutrient composition of bashang long-tail chicken raised in a cage and
free-range. In this paper, we found that the nutritional value of Bashang
long-tail chicken eggs under free-range was higher than that of caged eggs.
Acknowledgments
This
work was supported by Innovation Team Projects of Layer and Broiler in Modern
Agricultural Industry Technology System of Hebei Province (HBCT2018150201,
HBCT2013090206), Science and Technology Plan Project of Qinhuangdao City (201703A034)
and College Innovation Team Leader Training Program of Hebei Province
(LJRC004).
Author
Contributions
Li
Chang: Planning of study, standardization and execution of lab protocols,
collection and analysis of samples from experimental animals, analysis of data
and write up of manuscript, Jiguo Sun: Planning of
study, analysis of data and write up of manuscript, Xianglong
Li: Planning and execution of study, analysis of data and write up of
manuscript.
Conflict
of Interest
We
declare that we have no conflict of interest.
Data
Availability
All
data, models, and code generated or used during the study appear in the
submitted article.
Ethics
Approval
All
studies involving animals were reviewed and approved by the Institutional
Animal Care and Use Committee of Hebei Normal University of Science and
Technology, China. Procedures were performed in accordance with the Regulations
for the Administration of Affairs Concerning Experimental Animals (The State
Council of the People's Republic of China, 2011). Animals were humanely
sacrificed as necessary to ameliorate suffering.
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