Advancements in the identification of loci and chromosomal
regions affecting traits of economic interest open
opportunities for the improvement of milk production
traits in dairy breeds. Gene-assisted selection, that is, the
use of functional mutations responsible for differences in
phenotypes, is one of the options for marker-assisted
selection (Dekkers, 2004). Loci with known effects on
physiology of milk production have been proposed as
candidate genes and relationships between their polymorphisms
and several dairy traits have been studied