CONSTRUCTION OF MULTI-TRAIT SELECTION INDEXES AND EVALUATION OF GENETIC COST OF IMPOSING RESTRICTIONS ON CONSTITUENT TRAITS IN BROILERS

Selection indices with and without restrictions were constructed for White Rock (female line) and a Red Cornish (male line) population involving various broiler and reproductive traits using 2 sets of relative economic weights. The exclusion of egg production (38.12 and 66.77%) in the efficiency of the index followed by 8-week body weight. Adult body weight and egg weight were the least important traits in reducing the efficiency of the index. In sire-line, the exclusion of shank length, keel length and breast angle did not affect the efficiency of the index. The index involving the body weights at 2,4,6 and 8 weeks of age was more efficient for the improvement of 8-week body weight. From the restricted indexes, it appeared possible to keep mature egg weight and adult body weight at genetic equilibrium while permitting improvement in egg production to 280 days of age and 8-week body weight almost to the extent obtained from unrestricted index.