Comparison of index selection and best linear unbiased prediction for simulated layer poultry data

The advantage of using best linear unbiased prediction (BLUP) of breeding value over different selection indexes was examined for a sex-limited trait in a simulated layer poultry population. The base breeding population consisted of 30 males and 300 females that were unrelated to each other. Heritability for different analyses was assumed to be either .1, .2, or .5. Each generation was reproduced from two hatches each year, with a hatch variance of 3.165% of the phenotypic variance, except for one simulation, in which it was assumed to be 40% to test the effect of a large fixed effect. Parents were selected on 1) BLUP of breeding value, 2) optimum selection index (individual, full-, and half-sibs), 3) classical selection index (as for optimum, but index weight constant across generations), 4) reduced selection index (individual and full-sibs only), or 5) combination of classical and BLUP. The relative selection response with the selection indices compared to the BLUP estimates (except for the reduced selection index) were from 94.5 to 99.4% of BLUP. Inbreeding was higher in the BLUP selected populations, which could offset any advantage of BLUP if the populations were structured so that inbreeding could rise too rapidly.