Genome scan for the degree of white spotting in dairy cattle

White spotting is one of the most distinguishing visual characters in dairy cattle. There is considerable variation within and between breeds of cattle. The objective of this study was to map quantitative trait loci (QTL) affecting the degree of white spotting in dairy cattle based on an F(2) experimental design using Holstein-Friesian and Jersey crossbred cows. The genome scan was implemented using half-sib and line-of-descent approaches with high density markers. Significant QTL were found on chromosomes 6, 18 and 22. The mapped region on BTA6 confirmed the widely conserved KIT locus affecting mammalian pigmentation. Haplotype information linked the highly significant QTL on BTA22 to the Microphthalmia-associated transcription factor (MITF) gene, which has been reported to be associated with pigmentation traits in some other mammals.