Holsteins with the Dominant Red variant have red and white coats inherited in an autosomal dominant fashion. The gene underlying this coloration is independent from the other major gene (MC1R) that controls black and red color in Holstein cattle.
Phenotype: Holsteins with the Dominant Red variant are red and white. This phenotype may appear visually similar to or even indistinguishable from the red and white coat produced by the Recessive Red MC1R variant.
Mode of Inheritance: Autosomal dominant
Alleles: N = No Dominant Red, DR= Dominant Red
Breeds appropriate for testing: Holstein, Holstein crosses
Explanation of Results:
Cattle with N/N genotype do not have this Dominant Red variant, so their coloration is dependent on their MC1R genotype. They cannot transmit this Dominant Red variant to any of their offspring.
Cattle with N/DR genotype will be red and white. They will transmit this Dominant Red variant to 50% of their offspring, and those offspring will have the Dominant Red phenotype.
Cattle with DR/DR genotype will be red and white. All calves produced by these cattle are expected to be red and white regardless of the mate's genotype.
Dominant Red, as the name implies, is a dominant red color that occurs in Holstein cattle. The Dominant Red gene is independent from MC1R, a major gene controlling black and red color in Holstein. Dominant Red color is increasing in popularity among breeders. The mutation that causes Dominant Red has been identified by a team of researchers from the US, Canada, and Sweden.
Testing for Dominant Red allows breeders to identify homozygous animals (animals with 2 copies of the variant) which will always produce red and white offspring. The Dominant Red test is also useful in determining if an animal is red due to both MC1R and Dominant Red.
Other Holstein breed-specific tests offered by the VGL:
No copies of Dominant Red present. Color is dependent on MC1R genotype.
1 copy of Dominant Red present. Animal is red and white and 50% of offspring are expected to be red and white.
2 copies of Dominant Red present. Animal is red and white; all offspring are expected to be red and white.
Dorshorst, B.J., Henegar, C., Liao, X., Almén, M.S., Rubin, C.J., Ito, S., Wakamatsu, K., Stothard, P., Van Doormaal, B., Plastow, G., Barsh, G.S., Andersson, L., & Liu, J. (2015). Dominant Red Coat Color in Holstein Cattle Is Associated with a Missense Mutation in the Coatomer Protein Complex, Subunit Alpha (COPA) Gene. PloS One10(6): e0128969. doi: 10.1371/journal.pone.0128969