Genetic Mapping of the Bovine Genome Using Deoxyribonucleic Acid-Level Markers to Identify Loci Affecting Quantitative Traits of Economic Importance

Abstract

The first experiment designed to map loci affecting quantitative traits through linkage to Mendelian marker loci was carried out in 1923. In the past, application of these procedures was limited by lack of suitable genetic markers. The advent of immunological, biochemical, and, more recently, of DNA-level markers, has virtually removed this limitation, making possible an attempt to map most of the quantitative trait loci affecting traits of economic importance in dairy cattle. Theoretical studies show that experiments based on crosses will be most effective for mapping quantitative trait loci affecting traits whose value differs markedly between populations (e.g., populations differing in resistance or susceptibility to particular diseases). Experiments based on analyses of progeny groups within-sires will be most effective for mapping quantitative trait loci affecting traits showing considerable within-population genetic variation (e.g., growth-rate or milk production and composition). Analyses of progeny-tested sons of elite dairy sires can be an efficient means of mapping quantitative trait loci within dairy cattle populations. © 1990, American Dairy Science Association. All rights reserved.