Genetic studies on performance traits of egg type chickens
SANDEEP NARWAL, C.P.MALIK, K.L.RAHEJA AND SUNIL KALRA
Department of Animal Breeding, CCS Haryana Agricultural University
Observations on 765 pullets of strain H of White Leghorn, produced from 87 sires in different hatches over six generations, were used to study effect of generation and ‘hatch within generation’ on performance traits. The performance 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). Data were analysed by using Harvey’s least squares technique. Genetic and phenotypic (co) variability were calculated by paternal half-sib correlation method from hatch corrected data. Generation had significant effect (P≤0.01) on all the traits. Least squares means for BW20, BW40, AFE, EP40, EW40, CS1 and CS2 were 1236.01g, 1505.92g, 148.82 days, 90.17 eggs, 54.65g, 2.71 eggs and 2.70 eggs, respectively. Heritability estimates were low for all traits. BW20 had positive and significant phenotypic correlation (r p) with BW40. BW20 and BW40 showed negative genetic correlation (r g) with AFE and EW40 but positive with EP40 and CS2. AFE had negative and significant r p with EP40 and negative r g with EP40 and EW40 but positive r g with CS1 and CS2. EP40 had negative r g with CS1 and negative and significant r p with EW40. Results suggest that effect of generation should be included in the model. Low heritability estimates suggest use of family/combined selection. Correlations among these traits recommend that the index of BW20, AFE, EP40, EW40 and CS2 may be used to improve performance traits of this flock.