Estimation of genetic parameters and construction of multi-trait selection indices using various economic traits in broilers

Data from 750 pullets pedigreed by 29 sires and 145 dams were analyzed for weight at 20 weeks (BW²⁰), weight at 24 weeks (BW₂₄) age at sexual maturity (ASM), weight at sexual maturity (WSM), first egg weight (FEW), egg production upto 40 weeks (EP₄₀) and egg weight at 32 weeks (EW₃₂) of age and their averages were 1950.68±16.06 g, 2663.07±21.41 g, 191.63±4.72 days, 2728.57±2.89 g, 46.48±7.82 g, 41.87±7.87 eggs and 59.88±2.94 g, respectively. The heritability estimates for the above traits were 0.09±0.09, 0.09±0.08, 0.054±0.05, 0.25±0.12, 0.05±0.04, 0.05±0.05 and 0.l9±0.09, respectively. The phenotypic and genotypic correlations of BW₂₀ with BW₂₄, ASM and WSM were found to be positive while EP₄₀ and EW₃₂ were observed to be negatively correlated with the same trait on both the scales. The positive phenotypic. correlations between ASM and other traits were observed except with FEW. The correlations of first egg while weight were positive and WSM, EP40 and EW₃₂ while 20 and 24 weeks body weight and ASM were observed to have negative correlation with the same trait on phenotypic scale. A total of 12 selection indices incorporating four traits (7 indices) and three traits (5 indices) at a time using variances and covariances of the traits under study were constructed and their efficiencies have been compared. On the basis of R_IH and ΔH values, index I₆ (ASM, WSM, FEW and EP₄₀) and I₁₂ (WSM, FEW and EP₄₀ were found to be most efficient index having their R_IH and ΔH values as 0.615, 210.24 and 0.39, 135.93 among four and three trait combinations, respectively. The indices were:

I₆ = -5.767 (ASM) -+ 3.952 (WSM) + 0.151 (FEW) + 6.144 (EP₄₀

1₁₂ = 0.617 (WSM) + 0.194 (FEW) + 0.480 (EP₄₀).