Mapping of QTLS associated with milk production: Present status

Abstract

In 1923 Karl Sax, identified for the fírst time, loci affecting quantitative traits through linkage to Mendelian marker loci in Phaseolus vulgaris. Several decades later, the first studies about molecular markers and their possible association with milk production in domestic animals began. These studies were focused to the analysis of blood groups and biochemical polymorphisms. These results were contradictories because the different associations reported by the distinc groups were not coincident. For this reason it was necessary to develop simultaneously statistical methodology and tipification technology. In the last years the analysis was focused to the candidates genes and to sean the genome through microsatellites. The results evidenced that these markers are usefull for QTLs mapping. On the other hand, the improvement of experimental designs was an important fact to identify genes or chromosomal regions associated with milk production. The main objetive of this paper was describe the present status of dairy QTLs mapping.