Genome analysis to identify QTL and genes affecting carcass traits in Hanwoo ('Korean cattle')

Abstract

Most of economic traits are quantitative traits controlled by a large number of genes but some of these genes might have a large effect on quantitative traits in cattle. Such genes are called major genes located at quantitative traits loci (QTL). However, in practice, the term of QTL is linked allele associates with the gene controlling interest trait. If QTL explaining a part of genetic differences between animals are detected, the effect of the genes located at QTL could assist in estimating an animal's true genetic value. Therefore, information of QTL provide to accuracy of breeding value estimation as well as more genetic gain due to selecting animal at young animal. Marker assisted selection (MAS) is indirect selection process where a quantitative trait of economic important is selected not based on the trait itself but on a marker linked to QTL of the trait. MAS can be useful for traits that are difficult to measure, exhibit low heritability, and are expressed late in development. Major genes which are responsible for quantitative traits and QTL that are linked to major genes are first identified by using different techniques such as gene expression analysis and QTL mapping. Then, this information can be implemented for MAS in estimating breeding value. This thesis focused on using QTL mapping and microarray analysis to identify major genes and mutations that could be used to improve carcass traits in Hanwoo cattle. Finding causal genes or QTL which have a large effect on economically important traits would assist in improving the genetic gain through MAS schemes.