Coat Color of Cattle

The coat color of cattle is determined by genetics. Coat color and patterns depend on genes, independent or interacting with each other. A variety of coloration emphasizes the belonging to a distinct breed, the character of the species, and can also be the basis of selection criteria for animal breeding. Two main pigments are responsible for the coloration of cattle: eumelanin, which determines the color of the coat in black or brown, and pheomelanin, which determines the red or yellow color. Depending on their distribution and proportion, the pigments influence the uniform or patterned coloration of individuals.

The key role in determining the coat color cattle in the Holstein-Friesian breed is played by the MC1R gene located on chromosome 18. It is responsible for encoding the receptor that controls the activity of the enzyme tyrosinase, which synthesizes melanin and determines the levels of pigments produced. The polymorphism of the MC1R gene shows a strong influence on the coloration of individuals depending on the set of alleles present in the genotype. The primary alleles at the E locus determine black, red or wild color.

The dominant E allele determines the black color of the coat of individuals. The mutation affects the high activity of the receptor, the level of tyrosinase is also maintained at a constant high level, ensuring the production of the pigment eumelanin, which determines the dark color of the coat. Due to the dominant nature of the allele, both homozygous and heterozygous individuals will be characterized by black coloration.

The recessive allele e determines the red coat color of individuals. The mutation is associated with reduced or absent receptor activity. It is caused by a change in the amino acid sequence of the protein, leading to the formation of a premature STOP codon and the disappearance of the full functions of the receptor. The result of the mutation is a low level of tyrosinase and the production of the pigment pheomelanin, responsible for the red color of the coat. The recessive nature of the allele allows the appearance of red coat color only in homozygous individuals. Heterozygotes, on the other hand, can pass on the allele that conditions red coloration to their offspring.   

The wild-type E+ allele conditions the full expression of the pigments eumelanin and pheomelanin, characterizing the different coat color of individuals depending on the allele with which it occurs. The wild variant of the gene is also characterized by the frequent occurrence of distinct coloration in different parts of the animal’s body, such as the head, ears and limbs.

The presented genetic determinants within the MC1R gene presenting phenotypic traits of coloration were characterized for the Holstein-Friesian breed. The described gene also determines coat color for other cattle breeds: Angus, Simmental, Brown Swiss, Abondance, Fries Roodbont, Evolèner, Herens, Itäsuomenkarja, Original Schweizer Braunvieh, Rotes Höhenvieh, Limousin, Normande, Witrood Ras van Belgie.

The MC1R receptor is not the only factor determining the coat color of cattle. Its coloration effects are masked by the activity of the COPA gene, determining completely the red color of individuals. In addition to the E locus, the Agouti gene, at the A locus, is an important element affecting the color of cattle’s coat. It regulates the activity of the occurrence of black pigment, allowing the appearance of not only uniform but also patterned coloration, and influencing the separate coloration of individual body parts. 

REFERENCES #

1. Hong R, Yan Y, Zhu C, Zuo F i Zhang GW. Rapid genotyping of bovine MC1R gene c.296T>C and c.310delG haplotypes using high-resolution melting analysis. (2024). Anim Genet. 55(1):173-174.
   
2. Kasprzak-Filipek K, Sawicka-Zugaj W, Litwińczuk Z, Chabuz W, Šveistienė R i Bulla J. Polymorphism of the Melanocortin 1 Receptor (MC1R) Gene and its Role in Determining the Coat Colour of Central European Cattle Breeds. (2020). Animals (Basel). 14;10(10):1878.
   
3. Switonski M, Mankowska M i Salamon S. Family of melanocortin receptor (MCR) genes in mammals-mutations, polymorphisms and phenotypic effects. (2013). J Appl Genet. 54(4):461-72.