Study on distribution of coat color related alleles and white markings in a closed population of Lipizzan horses

Coat color represents one of the major selection criteria in horse breeding, and thus phenotypic color spectra directly correlate with the changes of breeding objectives and aesthetic attitudes. In this study we used the Austrian Lipizzan breeding herd of the stud farm Piber to illustrate this process by genotyping single coat color related loci (MC1R, ASIP, STX17, SLC45A2/MATP, PMEL17/SILV, SLC36A1, PAX(6)(7)(0Y), SB1), phenotypic analyses of white markings and comparisons with historical records from the early 18th cen tury. The majority of Lipizzans was gray (98,1%), whereas 80,6% were homozygous for the G-allele on the STX17 locus. Beyond the gray coat 81,1% of horses were bay, 18,9% were black, chestnut horses did not occur and three heterozygous buckskins were detected. Three Lipizzans were phenotypically spotted, which could be drawn back to the Dominant White locus (segregation of the W20 allele). Compared to the 18th century, it could be shown, that besides the drift on the gray locus towards homozygosity, a shift from black color towards bay color occurred. Heritability estimates for white markings varied from 23% to 71%. The results of this study allow a precise breeding plan and selection strategy in favour of more phenotypic variability of coat color.