ORIGINAL RESEARCH Genetic analysis of juvenile growth and carcass traits in a full diallel mating in selected colored broiler lines Ullengala Rajkumar & R. P. Sharma & M. K. Padhi & K. S. Rajaravindra & B. L. N. Reddy & M. Niranjan & T. K. Bhattacharya & S. Haunshi & R. N. Chatterjee Accepted: 17 February 2011 /Published online: 1 March 2011 # Springer Science+Business Media B.V. 2011 Abstract The juvenile growth and carcass traits were evaluated in a 4×4 full diallel crossing involving four colored broiler chicken lines viz., Naked neck (NN), Dwarf, Punjab Broiler-1 (PB-1), and Punjab Broiler-2 to study the performance and crossbreeding parameters. The data on 2,280 chicks were analyzed using least squares techniques to assess the effect of genetic group, and the significant traits were further analyzed for crossbreeding parameters. Genetic group had significant influence on the body weights and carcass traits. The cross of PB-1×NN recorded significantly (p ≤ 0.05) higher body weight at 6 weeks of age. The data revealed that general combining ability (GCA), specific combining ability (SCA), maternal ability (MA), sex-linked effect (SE), and purebred effects signif- icantly influenced the growth and carcass traits in the broiler crosses. The crossbred PB-1×NN showed positive heterosis for growth as well as carcass traits. The results suggest that GCA, SCA, SE, and MA are important in the inheritance of the body weights and carcass traits indicating the presence of both additive and nonadditive genetic variation along with reciprocal effects. Therefore, pure line selection along with development of specialized sire and dam lines followed by crossing will improve the growth performance and benefit the poultry farmers. It is concluded that PB-1 as a male line and NN as a female line performed significantly higher, therefore, may be used for improving the performance of colored broilers. Keywords Body weight . Diallel . Heterosis . Combining ability . Crossbreeding parameters Abbreviations NN Naked neck DD Dwarf PB-1 Punjab Broiler-1 PB-2 Punjab Broiler-2 GCA General combining ability SCA Specific combining ability MA Maternal ability SE Sex-linked effects PE Purebred effect Na Naked neck gene dw Dwarf gene F Frizzle gene g Grams Introduction The broiler chicken industry in tropical and subtropical climatic regions is facing a major challenge to overcome the heat stress caused by high ambient temperatures, the large poultry-producing segment in the world (Gowe and Fairfull 2008). When the ambient temperature and relative humidity exceed the comfort level of chicken, its ability to dissipate heat reduces due to feather insulation and high body weight, leading to change in hormonal status, reduced feed intake (Teeter et al. 1985) and reduced growth rate, feed efficiency (Geraert et al. 1996) and hatchability, and increasing mortality (Gursu et al. 2004), leading to major economic losses to the poultry industry. There is a need to minimize the ill effects of high ambient temperatures on U. Rajkumar (*) : R. P. Sharma : M. K. Padhi : K. S. Rajaravindra : B. L. N. Reddy : M. Niranjan : T. K. Bhattacharya : S. Haunshi : R. N. Chatterjee Project Directorate on Poultry, Rajendranagar, Hyderabad 500 030, India e-mail: ullengala@yahoo.com Trop Anim Health Prod (2011) 43:1129–1136 DOI 10.1007/s11250-011-9812-6