Submitted to: Encyclopedia of Dairy Science
Publication Type: Review Article
Publication Acceptance Date: December 12, 2001
Publication Date: December 12, 2001
Citation: VAN TASSELL, C.P., SONSTEGARD, T.S., KAPPES, S.M., ASHWELL, M.S., CONNOR, E.E. GENETICS, CATTLE GENOMICS. ENCYCLOPEDIA OF DAIRY SCIENCE. vol. 2, pp. 1219-1224, 2002.
Genetic improvement in cattle has been successful through the use of national genetic evaluation programs and artificial insemination (AI), especially for dairy cattle. However, the genetic models used for these evaluations universally assume that all genetic effects are infinitely small (called the "infinitesimal model"). From a biological perspective this is not a realistic assumption, because we know that individual genes control inheritance, and these effects must have finite effects. Facilitated by technological developments derived from the human genome project, initial genomics research in livestock was directed at developing anonymous genetic markers. These markers allow identification of genomic regions associated with traits of interest. These locations are usually called quantitative trait loci (QTL) or economic trait loci (ETL). The term QTL will be used here. A more recent area of investigation is functional genomics with a goal of determining the function of genes. An overview of these topics is discussed.