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 W hite Rock (female line) and a Red Cornish (male line) population invol ving various broiler and reproductive traits using 2 sets of relative economic weights. The exclusion of egg production (38.12 and 66.77%) i n the efficiency of the index followed by 8-week body weight. Adult bo dy weight and egg weight were the least important traits in reducing t he efficiency of the index. In sire-line, the exclusion of shank lengt h, keel length and breast angle did not affect the efficiency of the i ndex. 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 th e restricted indexes, it appeared possible to keep mature egg weight a nd adult body weight at genetic equilibrium while permitting improveme nt in egg production to 280 days of age and 8-week body weight almost to the extent obtained from unrestricted index.