Grey, Curly, and Short-Haired Swiss Holstein Cattle Show Genetic Traces of the Simmental Breed

In a study of 33 Swiss Holstein cattle with a unique fur phenotype characterized by curly, shortened pigmented hairs and a tendency for hair loss in pigmented areas, genetic analysis revealed that these animals were heterozygous carriers of two variants in genes associated with pigmentation. Specifically, they carried a gain-of-function variant in the MC1R gene, which causes dominant black coloration, and a loss-of-function variant in the same gene responsible for the recessive red factor. Additionally, they all carried a variant in the PMEL gene linked to a semi-dominant form of color dilution found in Simmental, Hereford, and Highland cattle. This genetic makeup is likely due to the historical crossbreeding of Holstein cattle with the Original Simmental breed, leading to the occasional appearance of this phenotype in Swiss cattle.