Selection of pullets and cockerels in a strain of White Leghorn: Mass selection
SANDEEP NARWAL, C.P.MALIK, D.S. DALAL AND A.K.VINAYAK
Department of Animal Breeding, CCS Haryana Agricultural University
The records of 765 birds (progenies of 87 sires) of strain H of White Leghorn were used for this study. The traits recorded were body weights at 20 and 40 weeks of age (BW20, BW40), age at first egg (AFE), egg production upto 40 weeks of age (EP40), egg weight at 40 weeks of age (EW40), clutch size upto 30 weeks of age (CS1) and clutch size from 31 to 40 weeks of age (CS2). The data were analysed by using Havey’s least squares technique. The expected direct and correlated responses in traits were calculated assuming selection intensity as 1.4 and 0.5 in pullets and cockerels, respectively. The information of half-sib pullets was utilized for individual trait selection of cockerels. The trend of response was almost same in pullets and cockerel selection. Selection of pullets and cockerels for BW20 would improve all the traits in desirable direction except marginal decrease in EW40. Selection for high BW40 would improve EP40 and CS2. Selection for early AFE would improve BW20, EP40 and EW40 with slight decline in CS2. Selection on the basis of EW40 would improve all the traits except slight decline in BW20. Selection for CS1 would improve BW20 and EW40 but decrease EP40 and selection for CS2 would improve all the traits except slight delay in AFE. Selection on the basis of EP40 would improve all the traits in cockerels also. In pullets, selection on the basis of EP40 would give direct response as 1.45 eggs in EP40 and correlated response of 2.31g, 2.82g, -0.38days, 0.11g, 0.03 egg and 0.01 egg in BW20, BW40, AFE, EW40, CS1 and CS2, respectively.