CHAPTER ONE
INTRODUCTION
1.0 BACKGROUND
OF THE STUDY
Layers are chickens that produce
commercial edible eggs. The eggs produced are not fertile to be used in
hatching of chicks. The production of edible eggs is the largest part in
poultry production in Nigeria.
Layers’ farming is popular to many producers because it has more values and is
regarded as being more profitable by many local farmers. (Pascool et al., 2008). There is tremendous
opportunity for growth in this sector. Another reason for the idea of profitability
is the ability to sell the spent chicken after laying period is over.
Egg is one of the most nutritious food
available to man. It provides a balanced protein which contains all the amino
acids considered essential in sufficient amounts and proportion to maintain
life and support growth when used as a sole source of protein food. In
addition, they have important functional properties (Kurtzweil, 1998). Egg
production is on the increase in Nigeria and poor storage conditions
may result in deterioration in egg quality and consequently, loss and waste of
eggs. More so, the economic success of a laying flock depends on the number of
quality eggs produced. Egg quality comprises a number of aspects related to the
shell, albumen and yolk and may be divided into external and internal quality
(Kul and Seker, 2004).
According to Keener et al., (2006) Haugh unit is a measure
of albumen quality and therefore freshness of the egg depends on albumen
quality while Silversides et al.,
(1993) proposed measuring albumen height to determine egg quality. Scott and Silversides
(2000), Jones and Musgroove (2005) reported a decrease in albumen height and
weight of eggs with storage leading to decreased egg weight. Williams (1992)
and Aciar (1998) observed that oiling of eggs within 24 hours of lay was
effective in retarding albumen deterioration but does not replace the need for
cool storage. According to Samli et aL
., (2005) storage time and
temperature appear to be the most crucial factors affecting albumen quality or
Haugh unit. In some part of Nigeria,
most of the available eggs are usually stored at room temperature until they
are completely sold or consumed because facilities for refrigeration are almost
non existent. Room temperature in Nigeria could be as high as 35oC
in the hot dry season when ambient temperature reaches 40-450C.
As an egg ages, the air cell becomes
large, the yolk become flatten, large and break more easily. The thick white
becomes thin and watery. However, European union countries classifies eggs as
class A,B, or C and the only egg graded class A can be sold directly or
retailed for human consumption (Council of European Union, 2006). Grade A egg
weight include the following;
|
WEIGHT CLASS
Jombo
Extra
large
Large
Medium
Small
Peewee
|
MINIMUM WEIGHT (GRAM)
70
63
56
49
42
Less
than 42
|
Grade
B are mostly used for commercial baking very few are sold in the retail stores.
The yolk is slightly flattened, white is thinner, shell is uncracked and may
have a rough texture and/or may be slighting soiled and stained. Grade C is the
lowest egg grade. It is used in the production of processed egg products only.
They are not sold in the store, the yolk is flattened and may be oblong in
shape I white is thin and watery. The shell may be cracked and/or stained.
Egg quality is a general term which
refers to several standards which determine both internal and external egg
quality. External quality is focused on the shell cleanliness, texture and
shape. Whereas internal quality refers to egg white (albumen) cleanliness and viscosity
size of the air cell, yolk shape and yolk strength. The monitoring of egg
quality characteristics of external and internal type is important mainly for
interest of economy of production (Lesson, 2006). The egg quality is given
through it’s weight and percentage of eggshell, thickness and strength. Proper
storage of eggs is essential to preserve the quality and cooking
characteristics. Improper storage condition can reduce the grade of eggs within
few days of lay. The principle degrading factors are high temperature and
dehydration. It is against this back drop that this project was designed to
find out the effects of different storage methods and duration on Bovan Brown
eggs at different stages of production.
1.1 Objective
of the Study
The objective of this study were to;
i. Determine
the effect of storage type (room temperature, refrigerator and air tight box)
on the internal and external quality characteristics and edible value of Bovan
Brown eggs.
ii. Evaluate
the effect of storage time in the external and internal egg quality traits of
laying hen.
iii. Evaluation the effect of age of the bird
on egg quality traits.
1.2 Justification
Quality determines the acceptability
of a product to potential purchasers. The maintenance of egg quality is a major
problem for those involved in egg marketing. The quality of egg and the
preservation of the quality is the function of their physical structure and
chemical composition.
The information from this research will provide
practical information to those who are immediately concerned with egg
production and marketing to know more about the best method and duration of
preserving eggs. This will enable them to satisfy consumers demand in relation
to quality of eggs.
The knowledge gained form this
research will help to know the effect of age of the bird on egg quality. This
will enable the producers to know the appropriate time to cull layers in
production.
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