Review on trends of Selection superior Dairy cattle through marker assisted selection methods

Abstract

Marker-Assisted Selection is selection that used for indirect selection of superior breeding animals that depend on identifying association between genetic marker and linked quantitative traits loci. Since the association between marker and quantitative traits loci depends on distance between marker and target traits. As soon as markers linked to quantitative traits loci have been identified, they can be used in selection programme of dairy cattle that is beneficial when the traits are difficult and expensive to measure and low heritability and recessive traits in dairy cattle. Therefore, Marker-Assisted Selection facilitate the exploitation of existing genetic diversity in breeding populations and can be used to improve desirable traits in dairy cattle. Indeed, currently Marker-Assisted Selection is the most widely used application of marker systems in selection of dairy breeding. Quantitative traits loci affecting milk yield has been identified on 20 of the 29 bovine chromosomes. quantitative traits loci for milk yield on chromosome 1, 3, 9 and 20 are with evidence of quantitative traits loci at lower reported frequency on other chromosomes (5, 7, 10, 12, 14 17, 18, 21, 23, 27 and 29). However, the main limitation of marker-assisted selection is increased cost involved in sample collection for genotyping and complete genotype information. Hence, this paper was aimed to review trends on selection of dairy cattle based on marker assisted selection approach.