Comparative study of genetic response in two WLH strains due to selection for egg production up to 64 wks of age
M.C. KATARIA, RAM GOPAL AND KHUB CHAND
Central Avian Research Institute
Izatnagar - 243 122
A Comparative study of genetic response was conducted in two WLH strains viz. IWH & IWI. The data were recorded on 1022 & 1226 pullets of IWH & IWI strains respectively, which were the progeny of 50 sires mated to 300 dams. Various economic traits measured were body weights and egg weights at various age; average age at sexual maturity & egg production up to 40th & 64th wk of age. The pullets matured at an average age of 148.64 & 152.20 days in IWH & IWI strains respectively. The average egg weight at 40th wk of age was observed to be 54.44 & 54.55 gm in the two strains (IWH & IWI); the estimates for 64th wk egg production were observed to be 191.48 & 171.99 eggs in IWH & IWI strains respectively.
Average genetic response for main trait of selection i.e. 64-wk egg production was observed as 1.51 & 1.60 eggs per generation in IWH & IWI strains respectively. Corresponding estimates of genetic response in 40th wk egg production were estimated as 1.12 & 0.84 eggs per generation. There was an indication of decline in body weights at 16th, 40th & 64th wk of age in H & I strains, which was significant only for 40th wk body weights in IWI strain. Age at sexual maturity declined significantly to the tune of –0.64 & -0.39 days in ‘H’ & ‘I’ strains respectively. There was general decline in egg weight at 40th & 64th wk of age in the two strains except for non-significant gain at 64-wk of age in IWI strain (0.33 ± 0.48 gm). The regression coefficient for various important economic traits in the control population indicated non-significant changes indicating its stability in eliminating the environmental trend.