Abstract
Several authors have concluded that the efficiency of index selection is not very sensitive to changes in the economic weights. In a reappraisal of the problem, using larger changes in the economic weights, it is shown that considerable losses in efficiency can be incurred. If one trait, or a few traits, dominate the index [as measured by the product of the economic weight (a) and the heritability (h2) for the trait], the efficiency will be sensitive mainly to changes in that trait. If there is a balance among traits (with similar ah2 values), then moderate losses in efficiency may be incurred through changes in the economic weights. Large losses in efficiency occur when 1) important traits are omitted or unimportant traits are given importance, or 2) when the direction of selection is reversed for an important trait. The implications for a comprehensive definition of breeding goals, and the effects of unexpected changes in requirements, from husbandry or market changes, are considered. Copyright © 1983. American Society of Animal Science . Copyright 1983 by American Society of Animal Science.