This article outlines the main steps and the contribution of INRA to the development of genomics, which has revolutionised over the last two decades the knowledge of livestock genome structure and function. The development in the 1990's of the first microsatellite marker maps quickly allowed the first major genes to be localised and numerous quantitative trait loci to be detected. Meanwhile, cytogenetics and comparative genomics studies allowed livestock genomics to benefit from advances in the knowledge of human and mouse genomes. At the end of the 1990's, the construction of high-density mapping tools such as radiation hybrid maps and large insert libraries made it possible to develop fine mapping programmes and to identify the first causative mutations. The early 2000's have been marked by the development of systematic gene expression tools, Le. micro-arrays and DNA chips, the start of the first animal genome sequencing projects, and the rise of genomic databases and bioinformatics. Available sequence data then made it possible to detect in silico their variations, in particular the numerous single point polymorphisms (SNP) and to finely characterise the structure of livestock population genomes. Genomics has also renewed breeding programmes, with the development of programmes for marker-assisted selection, for the characterisation and the management of genetic variability and of parentage control or traceability applications.
