الفهرس 
Description of sharkasi and naked neck chicken
Naked neck gene in chickenOnly 14 pages are availabe for public view
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Abstract
This experiment was carried out at poultry breeders farm,
Agriculture Research and Experiment Center, Shalaqan, Poultry
Production Department, Faculty of Agriculture, Ain Shams
University. This study was designed to comparing between native
Sharkasi and imported naked neck genotype by study the
productive and genetic performance. The naked neck and Sharkasi
birds used in this study were heterozygous. Some measurements
taken to compare between them: Incubation measurements
(crossbreeding, hatchability and embryonic mortality) – Meat
production traits (body weight, body weight gain, carcass
characteristics) – Egg production traits (sexual maturity
measurements, egg production traits & egg quality measurements)
– Morphological measurements – Histological parameters and
Genetic characters (AFLP Technique).
The main results could summarize as follows:
1. Incubation measurements:
1.1. Crossbreeding:
Two lines follow the Mendelian law and the native Sharkasi is an
incompletely dominant gene like the imported naked neck gene
and not a mutant in the native normal feathered breed in Egypt.
The ratio of normal feathered offspring in both lines has a higher
observed value when compared with the expected value of
Mendelian law, and the other genotypes (homozygous and
heterozygous) have a low observed value when compared with
the expected value of Mendelian law. This may be due to a
lethal effect during the incubation stage of the naked neck gene
in both lines that leads to low hatchability ratios for naked neck
embryos. The percentage of breast muscles of male chickens showed
highly significant difference between native Sharkasi (5.07%)
and imported naked neck chicken (10.65%), inversely, native
Sharkasi recorded highly significant difference for thigh muscle
(10.52%) than imported naked neck (5.90%).
Giblets didn’t show significant difference between native
Sharkasi and imported naked neck chicken.
There was no statistically significant difference obtained for
inedible parts, but the present result showed that the feathers
percentage recorded a significantly lower value in Shsh
chickens (4.77%) compare with Nana chickens (5.95%).
2.2. Egg production measurements:
2.2.1. Maturation measurements:
The birds which carry the Na gene were matured at 147 days of
age however they mature earlier than Sharkasi birds which
matured at 153 d.
The comb length was significantly longer in native line (3.23
mm) than imported genotype (2.69 mm).
Shank length, keel length and body depth were significantly
differed highly significant between the native and imported
chickens in favor of native Sharkasi.
2.2.2. Egg production measurements:
The Sharkasi chicken performed a higher value for egg
production rate (69.53%) than naked neck chicken genotype
which recorded (62.23%) under the summer conditions of Egypt.
A naked neck genotype had significantly higher egg weight
(48.96 g) compared to Sharkasi hens (40.58 g) during the test
period at ”22-33” weeks of age.2.2.3. Egg quality measurements:
2.2.3.1. External Egg Quality:
The breaking strength was significantly higher for naked neck
genotype (5.44 kg / cm3) compared to Sharkasi line (4.65 kg/
cm3).
Native Sharkasi showed a higher shell weight percentage than
naked neck genotype. Inversely, naked neck genotype showed
highly significant increase in shell thickness with and without
shell membranes (0.389 – 0.351 mm.) respectively, compared to
Sharkasi chicken ones (0.363 & 0.328 mm.).
2.2.3.2. Internal Egg Quality:
Imported naked neck genotype showed significantly higher
Haugh unit compared to native Sharkasi (83.01% & 67.78%)
respectively and for yolk index (41.16% & 38.73%) respectively.
Native Sharkasi sowed highly significant increase in yolk weight
percentage (32.47%) compared to imported naked neck
genotype (28.81%).
3. Morphological measurements:
There is a slight difference with a non-significant between
heterozygous native Sharkasi and heterozygous imported naked
neck in the area % of naked skin at the 4 weeks of age, the first
genotype recorded (36.89%) while the second one recorded
(33.91%) from total area of the body skin.
4. Histological Observations and Parameters:
In both lines (native and imported naked neck) sections; the
feather follicles weren’t found in naked regions of the neck, while
they were well developed in normally-feathered birds in the
same regions. Total epidermal thickness in Nana was (96.79 μm) and
significantly higher than Shsh (74.28 μm) at the embryo aged 16
days. while such difference decreased at 45 wk. of age with no
significant.
There were no significant differences between Nana and Shsh
for thickness of subcutaneous fat at both 16 d of embryo and 45
wk of age, while normal feathered chickens were recorded
significant lower values at 16 d of embryo age compares to the
other two genotypes, while these values become significantly
higher at 45 wk of age compares to the other two genotypes.
Nana genotype recorded had significant higher values (24.22
μm) for fat cell diameter compared to the Shsh strain (20.31 μm)
at 16 d of embryo age, but these values almost reversed at the
45 wk. of age, whereas Shsh individuals recorded highly
significant values (36.92 μm) for fat cell diameter compared to
the Nana genotype (33.64 μm) at 16 d of embryo age.
The smooth muscle layer thickness recorded insignificantly
differences between Shsh, Nana and the normal feathered ones
at the 16 d of embryo age, while at the 45 wk. of age the Shsh
line (747.38 μm) showed highly significant difference than Nana
genotype (574.96 μm).
5. Genetic characters (AFLP technique):
AFLP analysis of the two lines generated about 427
bands/fragments in total. All combinations for the two primers
resulted 350 AFLP polymorphic bands 82% between the two
naked neck chicken lines and 77 AFLP monomorphic bands
18%.
Polymorphic bands are shown the number of polymorphic bands
between the two lines was high in the three combinations of
primer 2 with a range of 65 polymorphic loci 92% & 6 monomorphic loci 8%, while the other three combinations of the
primer 1 shows low polymorphic bands relatively between two
lines with a ranged of 52 polymorphic loci 72% & 20
monomorphic loci 28%.
The sixth combination of (C6) gave a band of 152 bp that may
be specific for naked neck trait in chickens for both Egyptian and
French lines.
The current result showed that only one marker is associated
with presence or absence of the neck feathers in chickens.
In conclusion, the imported Naked Neck genotype may be in
most cases the same of native Sharkasi. While, Gene action of
productive performance (egg & meat production) for every
genotype differ according to strain because it’s quantitative traits
controlling with many genes. Then, we can utilize the Native Strain
as a dependent line in development programs.