The creation of a single integrated map incorporating all available mapping information for an unsequenced species provides the best possible resource for meta analyses of quantitative trait loci, for a backbone on which to assemble sequence and for comparative mapping. Using a strategy encapsulated in the Location DataBase, integrated maps for cattle, sheep and pigs have been produced from all publicly-available mapping information for these livestock species. A very useful tool for comparative mapping is the Oxford grid. Of particular interest are grids comparing an integrated map from an unsequenced species with the annotated sequence map from a sequenced species. By an additional iteration of the Location DataBase approach or a variant of the Oxford-grid software, it is possible to create a virtual genome of the unsequenced species, which is a map comprising predicted locations for all loci identified in the sequenced species.