Genetic improvement of egg number and egg weight antagonistic traits in hybrid layer - desired gain index

Data on performance traits of two purebred strain (H and C) and their reciprocal crosses (HxC, CxH) over nine generation was analysed. The performance traits were body weight at 20 and 40 weeks (BW20, BW40) of age, age at first egg (AFE), egg number to 40 weeks of age (EN) and egg weight (EW) of purebred and crossbred groups. Sire component of variances and co-variances among the traits were computed after accounting for generation and hatch effects. Desired gain indices were computed incorporating egg number and egg weight of purebred and crossbred, as well as including the AFE of purebreds to improve egg number and egg weight of crossbred layer. The desired gain assumed in egg number were 5, 10 eggs and 0, 1, 2, 3,4, 5g in egg weight and reduction of AFE by 5 days. Results revealed that selection goals comprising only EN and EW while including AFE as the component trait of the index could be the ideal strategy of selection.