With the applications of DN A marker technologies to the field of pig breeding, the molecular breeding techniques including the marker-assisted selection (MAS) and marker-assisted introgression (MAI) have emerged. The use of molecular markers combining with traditional breeding methods accelerated the progress of genetic improvement in pigs. The basis of MAS or MAI was to seek the major gene or marker which contributed genetically much to the target traits. Linkage mapping and candidate gene approach are tw...