This study was done to complete the fine mapping of intervals containing economic trait loci (ETLs) affecting carcass merit traits. Researchers at Colorado State University, Cornell, and Kansas State University are validating markers associated with genes influencing marbling, shear force and sensory panel evaluation of beef tenderness and initiate the commercialization of marker-assisted selection. Genetic Fine maps have been completed for the eleven most significant economic trait loci detected by the project, markers were selected for the Validation study and supplied to PE AgGen. Blood and tissue sampling is under way for the breeds and positional studies of the eleven economic trait loci have been started.