CARCASS CHARACTERISTICS AND IMMUNE STATUS OF NAKED NECK AND NORMALLY FEATHERED CHICKEN GENOTYPES

Abstract

SUMMARY Carcass measurements and some immunocompetence parameters were investigated in naked neck (NaNa & Nana) and normally feathered (nana) genotypes under summer season conditions of Egypt. Two hundred and ten broiler chicks (70 of each genotype) 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, 150 chicks (50 each genotype) chicks were randomly chosen for carcass evaluation. The present result indicated that the presence of Na gene in a double state significantly increased body weight, relative breast muscle weight and meat yield compared to normally feathered birds. However, the Nana genotype was intermediated in most cases. Concerning immunocompetence parameters, the presence of naked neck gene in a single manner significantly increased relative lymphoid organs weight compared to normally feathered genotype. Similar trend was not observed for homozygous naked neck genotype. With respect to cell-mediated immunity, the present result indicated that the NaNa and Nana genotypes was hyper responder to PHA-P injection compared to nana birds. In conclusion, under summer conditions of Egypt, broiler 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. Moreover, the naked neck birds had higher immune response compared to normally feathered ones.