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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. |