Comparison of selection based on phenotype, selection index and best linear unbiased prediction using data from a...

1. Selection based on three methods of estimating breeding values, Best Linear Unbiased Prediction (BLUP), selection index (SI), and phenotype (SP) were compared for three traits, juvenile body weight (JW), percentage breast meat yield (BM) and hen-day rate of egg production (EP) using records provided by a commercial broiler breeding company. 2. Product moment correlations were calculated between breeding values estimated by each method and averaged across sexes. A mean correlation of 0.69 was obtained between selection on SP and BLUP for JW. Mean correlations of 0.88 and 0.68 and 0.87 were obtained between SI and BLUP for the traits JW, EP and BM, respectively. 3. A mean estimated genetic response of 77.7% was obtained with SP for JW relative to BLUP in the absence of restrictions on the selection of close relatives. Estimated genetic responses of 90.7%, 66.9% and 88.4% were obtained by SI relative to BLUP for JW, EP and BM, respectively. 4. Applying restrictions on the selection of close relatives resulted in slight decreases in estimated responses but not in the respective ranking of the selection methods. 5. The results indicate that BLUP could provide commercial breeders with increased selection responses compared to index selection, in particular for traits of low heritability and where relatively few animals possess performance records.