Impact of Naked Neck (NA) Gene, Sex and their Interaction on Live Growth Performance and Carcass Characteristics of Broiler Chicks under Summer Season of Egypt. Egyptian.

Abstract

Heterozygous naked neck (Nana) males were artificially inseminated with normally feathered (nana) female broiler chicken. At hatching, all chicks were wing banded and brooded in electrical brooding batteries. Then, at 3 weeks of age, they were transferred to floor pens. All genetic groups were reared under similar environmental, managerial and hygienic conditions. The feed and water were provided ad libitum. The average high and low ambient temperatures recorded during the experimental period were 32.5 and 28.7°C, respectively. At 6 weeks of age, two hundred chicks (50 chicks /sex /genotype) were randomly chosen for carcass evaluation. 2. It could be speculated that the presence of Na gene significantly increased keel length, shank length, relative breast muscle weight and meat yield by 2.5, 1.9 and 8.1%, respectively compared to normally feathered ones. Inversely, the Nana genotype had significantly lower relative abdominal fat weight (-10.7) compared to nana ones. Moreover, the effect of naked neck gene on carcass characteristics was more pronounced in male chicks rather than female ones. 3. With respect to correlation coefficients between live performance and carcass characteristics, it could be noticed that the live body weight is a good predictor for most carcass characteristics. Also, the keel length and breast width are good predictor for breast muscles in broiler chicks. 4. In conclusion, under summer season of Egypt, carcass composition could be improved by incorporating naked neck (Na) gene for increasing relative breast muscles and relative meat yield and decreased relative abdominal fat weight.