UC Davis School of Veterinary Medicine Veterinary Genetics Laboratory
Cattle Coat Color Tests

Several genes are involved in the process of creating the complex coat colors and patterns found in domestic cattle. One of these is the Melanocortin 1 Receptor (MC1R) gene, also called Extension, that controls the production of black (eumelanin) and red (phaeomelanin) pigments. The three alleles (forms) of this gene are dominant black (ED), Wild type (E+) and recessive red (e). Dominant black (ED) is dominant to the other two alleles and animals with this allele are jet black (solid or spotted). The Wild type (E+) produces cattle with reddish brown to brownish black coloration with a tan muzzle ring. Two copies of the recessive red (e) allele will result in red color. The other coat color genes act as modifiers of these base colors adding white spotting patterns, reorganizing the distribution of red and black pigments (Brindle and Agouti) or diluting the pigments (Dun, Charolais dilution and Simmental diution).

* In Holsteins, there are two other variants that can mask the effects of the other MC1R (Extension) alleles. These are known as 'Black/Red' (red color changes to black) and 'Variant Red' (dominant red color). This test for MC1R does not detect these alleles.

Allow 2-6 business days for results.

MC1R (Extension)

Results are reported as:


Dominant black. This animal cannot produce red offspring*


Dominant black, carrier of wild type


Dominant black, carrier of recessive red


Wild type


Wild type, carrier of recessive red


Recessive red. When bred to another 'e/e' will produce only red offspring


Veterinary Genetics Laboratory, Tel 530-752-2211, Email VGL