1682 Environment & Ecology 31 (4) : 1682—1684, October—December 2013 Website : environmentandecology.com ISSN 0970-0420 Non-Genetic Factors Influencing Juvenile Body Weight in a Colored Broiler Dam Line L. A. Bindya, T. N. K. Murthy 1 , M. Ashok 2 , B. C. Umashankar, G. M. Satheesha, B. U. Umesh Received 18 June 2013; Accepted 13 July 2013; Published online 24 July 2013 Abstract The present study was undertaken to evalu- ate the performance of a pedigreed closed flock of synthetic broiler breeder dam line (PB-2) maintained at the All India Co-ordinated Research Project on Poultry Breeding for Meat, Bangalore for juvenile body weight. Data on the juvenile body weight at five weeks of age of three (S 8, S 9 , S 10 ) generations from 2004 to 2006 and had undergone ten genera- tions of sire-family selection for the trait, were utilized for the study. The chicks were obtained in four ( S 8 , S 10 ) or five (S 9 ) consecutive hatches in each genera- tion with an interval of not more than ten days be- tween the hatches. The overall means for juvenile body weights at five weeks of age in the strain ranged from 866.90 ± 3.13 to 1014.26 ± 1.90 g over the genera- tions. The hatch wise means for body weight at five weeks ranged from 843.67 ± 6.62 to 891.66 ± 6.20 g in S 8 , 894.92 ± 4.93 to 99.5 69 ±3.5 g in S 9 and 984.87 ± 3.16 to 1065.26 ± 3.54 g in S 10 generation. The hatch LA Bindya, TNK Murthy 1 , BC Umashankar, GM Satheesha, BU Umesh 1 Assistant Professor Veterinary College, Shimoga, Karnataka Veterinary and Animal and Fisheries Sciences University, Bidar, Karnatataka M Ashok 2 Krishi Vigyan Kendra, University of Agricultural Sciences, Bangalore, Karnataka e-mail : drkrishnamurthytn@gmail.com *Correspondence effect operated like a non-orthogonal non-genetic source of variation masking the true genetic varia- tion. Hatch effects significantly influenced the juve- nile body weights in all the generations. The mean body weight of males and females at five weeks of age ranged from 916.02 ± 1.74 to 1079.86 ± 1.66 g and 816.76 ± 1.88 to 947.04 ± 1.99 g respectively and im- proved as generations advanced. Sexes differed sig- nificantly with males weighing heavier than the fe- males lending credence to the phenomenon of sexual dimorphism. Keywords Juvenile body weight, Hatch means, Brolier. Introduction The differential contribution of sire and dam for the production of commercial broiler chicks and the nega- tive genetic correlations between the growth and re- production traits warrant the use of specialized male and female lines in broiler breeding. A broiler dam line is selected for egg production and allied traits after a primary selection for juvenile body weight at five or six weeks of age. Various non-genetic factors like date of hatch and sex of chicks are found to influence the juvenile body weight from generation to generation. Therefore, the present study was undertaken to study the extent of influence of different non-genetic fac-