Materials
and Methods
Experimental
Site
The study was carried out at the Poultry
And Research Unit Of The Department Of Animal Science, Faculty of Agriculture
and Natural Resources Management, Ebonyi
State University,
Abakaliki. The study lasted for a period of four weeks (28 days).
Experimental
Animals
Bovan Brown birds raised on battery
cage system at different stages of production were used for the experiment. The
birds were served with commercial layer’s mash that contained 16% crude protein
and 2,500 kilocal/kg of energy. Clean drinking water was also given, regular
medication and vaccination was also carried out during the period. The stages
at which the eggs were collected were 30 weeks, 52 weeks and 72 weeks of age.
Experimental Procedures.
Seventy eight (78) newly laid eggs
were collected at each stage of production from the birds used for the study,
making a total of two hundred and thirty six eggs for the three stages of
production. Six eggs were selected at random from each stage of production
(eighteen eggs for the three stages) to determine the internal and external egg
quality. The remaining two hundred and sixteen eggs were numbered and randomly
allotted into three experimental groups of seventy two eggs each (twenty four
eggs from each stage of production).The experimental groups were randomly
allocated to the following storage methods: room temperature at 230 ,refrigerator
at 50c and air tight box at 30cm depth. The eggs were stored using
different storage method for each duration apart from day one. The storage
periods were seven days, fourteen days, twenty one days and twenty-eight days.
Data
Collection
The eggs were numbered and weighed
with sensitive balance immediately after collection from the pen to get the
initial weight. The internal and external quality of the eggs at each stage of
production were taken periodically at 7 days interval for a total of 28 days.
The external quality data that were measured were;
(a) Egg weight (g)
(b) Egg length (cm)
(c) Egg width (cm)
(d) Egg shell weight (g)
(e) Egg shell thickness (mm)
(f) Egg shape index (%)
The internal quality also measured
such as
(a) Albumen weight (g)
(b) Albumen height (mm)
(c) Albumen width (cm)
(d) Yolk weight (g)
(e) Yolk height (mm)
(f) Yolk width (cm)
(g) Haugh unit (%)
(h) Yolk pH
(1)
Albumen pH
The egg weight, shell weight, albumen
weight, yolk weight were measured using a sensitive scale balance (Mahler
P1210). Shell thickness were measured at different points of the broad end,
middle portion and narrow end using a micrometer screw gauge. The egg shape
index was estimated using the following formular (egg shape index = width of
egg/length of the egg x 100%). The egg width, egg length, albumen width,
Albumen height, yolk width and yolk height were measured using a vernier
caliper. The albumen pH and yolk pH was determined using pH meter. The Haugh
units were estimated according to the formula
Hu = 100
log (h+7.51-1.7w0.37)2 .Where
Hu = Haugh
unit
H = Observable
height of the albumen (mm)
W = Weight
of egg (g) (COtta, 1997)
Data
Analysis
Data obtained on internal and external
egg qualities measured were subjected to descriptive statistics so as to obtain
the means and the standard error or their means. A one-way analysis of variance
(ANOVA) were used to determine the effect of age, duration and storage methods
on the internal and external egg quality. Significant means were separated
using Duncan’s
New multiple Range Test (DNMRT) according to Obi (2002). SPSS (2009)
statistical package were used for the statistical analysis.
The statistical model adopted were;
Yij = m + ai + ∑ij
Where
Yij = Observation
of the ith duration and jth storage method
on egg quality
m =
Sample mean for the parameters being considered
ai = random effect of ith duration on jth
storage
I = fresh egg (first day), 7 days, 14 days,
21days, 28 days
J = Room
temperature, refrigerator and air tight box.
∑ij = Experimental
error.
RESULTS
EFFECT OF STORAGE METHODS ON THE
EGG QUALITY TRAITS
The result of the effect of storage method on the egg
quality traits is presented in the table 1.
TABLE 1: EFFECT OF STORAGE METHODS ON THE EGG
QUALITY TRAITS
|
Traits
|
Control
(Fresh egg)
|
Airtight
|
Room temp
|
Refrigerator
|
SEM
|
|
Egg Weight
|
59.43
|
59.48
|
60.74
|
60.32
|
1.205
|
|
Egg Length
|
5.52
|
5.62
|
5.62
|
5.66
|
0.07
|
|
Egg width
|
4.31
|
4.33
|
4.34
|
4.38
|
0.05
|
|
Egg shape index
|
77.17
|
77.09
|
77.36
|
77.37
|
0.79
|
|
Shell weight
|
7.40
|
7.48
|
7.49
|
7.58
|
0.15
|
|
Shell thickness
|
0.26
|
0.26
|
0.26
|
0.26
|
0.00
|
|
Albumen weight
|
35.29
|
33.99
|
33.78
|
34.68
|
0.90
|
|
Albumen height
|
0.67a
|
0.41b
|
0.41b
|
0.60a
|
0.03
|
|
Albumen width
|
4.46c
|
6.77ab
|
7.17a
|
6.38b
|
0.17
|
|
Albumen pH
|
8.31a
|
9.56b
|
9.66b
|
8.88a
|
0.54
|
|
Yolk weight
|
17.22b
|
17.83b
|
20.09b
|
17.98b
|
0.08
|
|
Yolk height
|
1.51a
|
1.17bc
|
1.08c
|
1.32b
|
0.13
|
|
Yolk width
|
3.95c
|
4.29b
|
4.66a
|
4.07bc
|
0.18
|
|
Yolk pH
|
7.15d
|
8.85b
|
9.20a
|
8.07a
|
0.13
|
|
Haugh unit
|
95.94a
|
80.97abc
|
75.90c
|
93.86ab
|
7.65
|
abcd means on the same row followed by different
superscript are significantly different (P<0.05); SEM:- Standard Error of
the means.
The
effect of storage method on the egg quality traits were found to be significant
at (P<0.05) for all internal quality traits considered. The mean of fresh
eggs were significantly different from the eggs in the airtight box, room
temperature and refrigerator. The albumen height, albumen pH and Haugh unit of
refrigerated and fresh eggs were not significantly different (P>0.05). It
was observed that refrigerated eggs were able to retain their albumen height,
albumen pH and Haugh unit like that of fresh eggs.
Effect of holding period on the egg quality traits
The result of the effect of holding period on the egg
quality traits is presented in the table 2.
TABLE 2: EFFECT OF HOLDING PERIOD ON THE EGG QUALITY
TRAITS
|
Traits
|
Control
|
7 days
|
14 days
|
21 days
|
28 days
|
SEM
|
|
Egg Weight
|
59.43
|
60.78
|
60.12
|
60.26
|
56.69
|
1.24
|
|
Egg Length
|
5.52
|
5.61
|
5.61
|
5.66
|
5.66
|
0.07
|
|
Egg width
|
4.31
|
4.33
|
4.35
|
4.36
|
4.36
|
0.05
|
|
Egg shape index
|
77.17
|
77.29
|
77.30
|
77.29
|
77.22
|
0.81
|
|
Shell weight
|
7.40
|
7.51
|
7.68
|
7.33
|
7.35
|
0.16
|
|
Shell thickness
|
0.26
|
0.26
|
0.26
|
0.26
|
0.26
|
0.00
|
|
Albumen weight
|
35.29ab
|
35.81a
|
33.76b
|
33.40b
|
33.63b
|
0.93
|
|
Albumen height
|
0.67a
|
0.54b
|
0.49bc
|
0.44c
|
0.43c
|
0.03
|
|
Albumen width
|
4.46c
|
6.23b
|
6.71a
|
7.01a
|
7.15a
|
0.18
|
|
Albumen pH
|
8.13a
|
9.21b
|
8.96b
|
9.72a
|
9.56ab
|
0.18
|
|
Yolk weight
|
17.22bc
|
16.94c
|
18.51ab
|
19.08a
|
20.00a
|
0.55
|
|
Yolk height
|
1.51a
|
1.41a
|
1.14bc
|
1.18b
|
1.01c
|
0.08
|
|
Yolk width
|
3.95c
|
3.98c
|
4.17bc
|
4.31b
|
4.91a
|
0.13
|
|
Yolk pH
|
7.15d
|
8.23c
|
8.58bc
|
8.90ab
|
9.11a
|
0.14
|
|
Haugh unit
|
95.94a
|
85.02ab
|
86.47ab
|
77.75b
|
85.06ab
|
7.97
|
abcd means on the same row followed by different
superscripts are significantly different (P<0.05); SEM standard Error of the
means.
The effect of holding period on the
egg quality traits were found to be significant (P<0.05). Albumen height,
albumen width, yolk height, yolk width and yolk pH were significantly different
from the fresh egg. The albumen height and yolk height consistently decreased
over increased holding period. In addition, the albumen width, yolk width and
yolk pH increased over increase in holding period. However, albumen weight,
albumen pH, yolk weight and Haugh unit showed little or no significant
difference (P>0.05).
EFFECT OF AGE OF THE BIRDS ON THE
EGG QUALITY TRAITS
The result of the effect of age of the birds on the
egg quality traits is presented in the table 3.
TABLE 3: EFFECT OF AGE OF THE BIRDS ON THE EGG
QUALITY TRAITS
|
Traits
|
Stage 1
|
Stage 11
|
Stage 3
|
SEM
|
|
Egg Weight
|
56.85c
|
59.66b
|
63.93a
|
0.73
|
|
Egg Length
|
5.51b
|
5.55b
|
5.85a
|
0.04
|
|
Egg width
|
4.25c
|
4.33b
|
4.46a
|
0.03
|
|
Egg shape index
|
77.18ab
|
78.12a
|
76.51b
|
0.48
|
|
Shell weight
|
6.92c
|
7.40b
|
8.21a
|
0.10
|
|
Shell thickness
|
0.26
|
0.26
|
0.26
|
0.00
|
|
Albumen weight
|
32.07c
|
34.18b
|
36.46a
|
0.55
|
|
Albumen height
|
0.48b
|
0.49b
|
0.50a
|
0.02
|
|
Albumen width
|
6.23b
|
6.66a
|
6.89a
|
0.11
|
|
Albumen pH
|
8.92b
|
9.50a
|
9.42a
|
0.11
|
|
Yolk weight
|
17.16b
|
17.87b
|
20.54a
|
0.33
|
|
Yolk height
|
1.19b
|
1.31a
|
1.13ab
|
0.05
|
|
Yolk width
|
4.28
|
4.25
|
4.40
|
0.08
|
|
Yolk pH
|
8.08b
|
8.86a
|
8.82a
|
0.08
|
|
Haugh unit
|
91.04a
|
86.96a
|
75.57b
|
4.65
|
abc means on the same row followed by different
superscripts are significantly different, SEM:- Standard Error of the means.
The effect of age of the birds on the
egg quality traits were found to be significant at (p<0.05) It was found
that egg weight, egg length, egg width, shell weight, albumen weight, albumen
width and yolk weight increased with increase in hen’s age. The egg shape
index, albumen pH, yolk pH, yolk height showed little significant difference.
The egg shell thickness albumen height and yolk width showed no significant
difference while the Haugh unit decreased with increase age of the hens.