Abstract: Genetically elite ungulate mammals are identified on the basis of gene expression profiles from biological samples such as liver and blood. Methods and compositions are presented to select genetically elite animals with a desired phenotype such as high milk production for breeding to improve production levels. A method to select an animal with a specific phenotype, e.g. milk production and health traits, includes creating a Gene Expression Index for a specific phenotype and using the index to identify candidate animals for breeding by comparing the index to gene expression profiles of the animals.