Shortcomings of current genetic evaluation systems.

Genetic evaluation, as the term is used today in the beef cattle and sheep industries, refers to the calculation and dissemination of genetic predictions for individual traits. If genetic predictions are to be used wisely, however, genetic evaluation should be broadened to include multiple-trait selection technology, preferably technology that is customized for individual commercial and seedstock producers. Most of the recent research in the area of genetic prediction/multiple-trait selection has focused on the use of economic selection indexes that incorporate genetic predictions produced within breeds. This approach is complicated by genotype x genotype, genotype x environment, and more complex interactions, and the changing correlations they create. The use of a mechanistic technology, bioeconomic simulation, to calculate economic weights can avoid some of the problems caused by interactions, but to implement this technology, academic animal breeders must accept the mechanistic concept of genetic potential and devise ways to translate current within-breed genetic predictions to predictions of this new measure. Sire selection by simulation, a multiple-trait selection technology described in detail in this article, uses bioeconomic simulation in a way that offers advantages over traditional selection indexes in terms of both functionality and appeal. For any customized technology to be applied on a meaningful scale, research priorities must change, and the business relationships between research groups and animal breeding industries must be restructured.