Long term selection for body weight and egg production in a flock of colored broiler dam line (PB2)

H.N. Narasimha Murthy1 and H. Khosravinia2
1. AICRP on poultry breeding for meat, Veterinary College, Hebbal, Bangalore - 560 024
2. Departement of Technology of Animal Products, Agriculture Faculty, Lorestan University, Khoramabad, P.B. 450, IRAN

Nine generations of double stage mass selection for body weight at 6 or 5 weeks and egg production at 40 weeks of age were carried out. Selection intensity was not consistent for all generations and ranged from 2.52 to 3.94 and 1.70 to 2.01 for males and females respectively. The linear model fitted for mean body weight (6w) against generation showed an average genetic gain of 11.68 g per generation. From generation 7 up to generation 9, body weight at 5w was targeted as selection criterion and -5 g response per generation was achieved. The linear model fitted for egg production up to 40 weeks against generation revealed an average genetic gain of 2.147 eggs per generation. The initial (generation 0) body weight (6w) and egg production were 1132g and 57 eggs. The linear models provided for mean feed conversion ratio, body weight (20w), age at sexual maturity and body weight (40w) against generation illustrated the average correlated responses of -0.0158 (g:g), -18.242 g, -1.17 days and -20.5 g per generation, respectively. The corresponding records at the commencement of the selection program (generation 0) were 2.46 (g:g), 2711g, 171 days and 3800 g. With respect to the performance of the flock for traits targeted in the last three generations, it is concluded that to enhance the performance of flock for the traits concerned, certain alteration in the breeding program as well as managerial practices are required. Selection of male and female breeders based on an index with diverged Wight age factors for body weight, egg production and egg weight, providing artificial light during laying period, practicing restricted feeding during breeding program based on different body weight groups and finally changing the environment of the selection by reducing the energy and protein levels in the diets supplied by 100 kcal ME/kg and 2%, are the suggestions to achieve the objectives concerned.

Source : IPSACON-2005

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