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Coat Color in Cattle

Miniature-Cattle.com breeding miniature cattle coat color (CC) genetics see also: DNA Tests in Cattle
Related Article: Genetics of Highland Coat Color. In this article I will attempt to explain what is known about the genetics behind coat colour in Highlands and some thoughts we have on what is as yet unproven. By Glen Hastie, Bairnsley Scottish Highland Cattle, Victoria, Australia. This article also references many major sources for information about this topic on the internet.
Related Article: Genetics of Coat Color in Cattle, a brief review of what is currently known about the genes controlling cattle coat colors and patterns. By Sheila M. Schmutz, Ph.D., Professor Department of Animal Science College of Agriculture and Bioresources University of Saskatchewan Saskatoon, Canada. This is a major source of information on the internet about bovine coat color.
Related Article: Color Patterns in Crossbred Beef Cattle,” Megan Rolf, Oklahoma State University
Related Article: White Park Colour Pattern Research paper presented to the White Galloway conference in Germany in 2014.
Related Article: Red Genetics. Color Genetics explained in all breeds of cattle - featuring the Redliner (red Lowliner)
Related Article: Cattle Colour Genetics A blog studying spotting and hereford marking genetics, by a rancher in Saskatchewan.

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Extension Black and Red Coat Color is determined by the Melanocortin 1 Receptor (MC1R) gene, also called Extension, which controls the production of black (eumelanin) and red (phaeomelanin) pigments. The illustration above shows the genetic probability of the results when breeding black and red cattle together (click to open full-size in separate window). The MC1R DNA test identifies 3 gene variants that affect the coat color of both beef and dairy cattle. Black (ED) is dominant. The Wild type (E+) produces cattle with reddish brown to brownish black coloration with a tan muzzle ring. Wild red is usually homozygous in the colored dairy breeds (Jersey, Guernsey, etc.). True red (e) is recessive and is only expressed when two copies are present. The DNA test for MC1R does not detect these alleles. [Labs that test Extension: Biogenetic Services, UC Davis VGL, Zoetis]

In Holsteins, there are two other variants that can mask the effects of the MC1R (Extension) alleles. These are known as 'Black/Red' (red color changes to black) and 'Variant Red' (red that is dominant over black).

an informal discussion of black, wild red, red, dun, agouti & brindle
Color Genetics in Galloway Cattle
Alan S. Bias, administrator, Galloway Cattle Genetics Discussion Group

Unfortunately, most registries were started by “laymen” who assign "color classes" by phenotypical observation and not genotype. Not to single out, but let’s just use the American Galloway Breeders Association (AGBA) as an example. The AGBA registers three solid colors; Black, Red and Dun.

There are two immediate issues that arise from this classification of “color”.

First, not all “Reds” are red, i.e. Wild-Type Red is not Red by genotype. Rather, only by phenotypical observation (what the eye perceives).

Second, “Dun” is a dilution of color, and not a color in itself. Though, to be fair, if the AGBA views “Dun” as a color, it is consistent in registering both Dun Black and Dun Red under “Dun”. The reasons will become clearer as you read on…

DEFINING COLOR: Solid coat color in cattle results from the presence or absence of melanin in hair coat.

  • eumelanin “black”
  • phaeomelanin “red”

As hair grows during embryonic development, melanocytes develop and migrate to the follicles to produce pigment. Further traits can modify color coat in utero, shortly after birth or with aging. Additional traits in turn can modify for spotting or pattern.

The Melanocyte Stimulating Hormone Receptor Gene (MSHr), also called the Melanocortin Receptor 1 gene (MC1r) is the source of all black or red hided Galloways.

The MC1r gene has two common alleles in cattle:

  • dominant (ED)
  • recessive (e)

An animal with (ED) present is always black. The (ED) allele is dominant to (e). Cattle that are (e/e) are the recessive genotype red.

EXTENSION: In addition, a less common allele (E+) also called "wild-type" occurs. The (ED) allele is dominant to (E+). Solid Black, Red and Wild-type Cattle are the result of Extension (E) locus:

  • dominant (ED) (black)
  • "wild-type" (E+) (black/red)
  • recessive (e) (red)

The accepted order of dominance is ED > E+ > e. Extension regulates the levels of tyrosinase. High concentrations of this enzyme result in production of eumelanin (black pigment), while low concentrations of this enzyme result in the production of phaeomelanin (red pigment). It is possible Galloways have additional types of Extension other than (E).

BLACK: The black allele is abbreviated (ED). The E stands for Extension, and the subscript D stands for dominant black.

RED: The red allele is abbreviated (e). Lower case is used to indicate that the allele is recessive to the other two alleles for color (ED) & (E+).

WILDTYPE: The wild-type allele is abbreviated (E+). The superscript + symbol is used to designate a wildtype allele. Initial color coat testing done on Wild-Type Reds during the 1990s by GenMARK concluded at the time these animals were heterozygous black (Bb). Wild-Type Red animals have deep burgundy red bodies. The extremities (head, neck, feet) appear to be black from a distance. But when viewed up close or in natural sunlight the red coloration is visible down to the root. While in Galloways, Wild-Type Red appears to result from Extension (E+), reports of Agouti (A+) influence has been suggested in other breeds.

Wildtype alleles produce both eumelanin and phaeomelanin through intermediate amounts of tyrosinase. The ratio and distribution of these two pigments may be modified by other genes. The visible expression of eumelanin seems sex linked. This can be observed in wild-type (E+) bulls, which express a darker head, neck and feet as compared to females.

Individuals with wildtype coloration can be homozygous for the wildtype allele (E+/E+) or they can be heterozygous for the wildtype allele with one dominant black (E+/ED) or one recessive red allele (E+/e). Inheriting one allele from each parent.

Heterozygous (E+/ED) are most often dark black in color, since even one copy of ED will produce an over-abundance of eumelanin. In heterozygous (E+/ee) variability of coloring in these animals is expected, and poorly documented.

AGOUTI: E+ can be further modified by the Agouti (A) locus. Agouti comes in several forms and has distinct effects depending upon combination. It is not well understood or documented across breeds. The existence of a recessive black Agouti allele (a) has been postulated with some supportive documentation, having the effect of modifying Wild-type E+ black/red to black. Thus, not all phenotypical “black” animals may be black (ED/ED).

Again, as with Extension, it is possible Galloways have more than one type of Agouti in genotype. To touch on briefly, the suggested allele (Abp) is epistatic (dominant) to ED and hypostatic (subordinate) to E+.

In combination with ED, Agouti is not likely visible. In combination with E+ results in very dark Wild-type; expressing not only varying degrees of red, but also locations of red on the body.

The allele (aw) is recessive and will remove red pigment; leading to the illusion of evenly distributed black melanocytes on the body of Wild-type E+, mimicking a black animal.

BRINDLE: Current studies indicate the Wild-Type Red (E+) allele is responsive to agouti in patterned & brindle animals. We have long known that both wild-type black (E+/E+) and wild-type red (E+/e) cattle exist in Galloway Populations. We now know the brindle trait exists in wild-type (ED/E+ Abr, E+/ E+ Abr) Galloway Populations, thus showing that wild-type can be further modified by pattern and spotting traits.

As early as 1949 Berge (1949) reported brindle a result of co-expression of two distinct traits in Nordic cattle. More recently, Oulmouden (2000 & 2006) showed brindle to be the result of Agouti (Abr) in Normande Cattle.

Thus, we now know brindle to be comprised of E+/Abr. Brindle is a striping pattern distinct from spotting (S). Most visible on wild-type black animals, less so or nearly invisible on wild-type red, comprised of black and yellow / red color pigments.

With wild-type long present in Galloway populations, it should come as no surprise that this phenotype has been resurrected in the German Neanderthal Galloway herd of Hartmut Kindel (above).

DUN: Dun Galloways express in three primary phenotypes: Chocolate, Golden and Silver.

Golden dun results from heterozygous codon deletion within the PMEL gene (p.Leu18del) PMEL +/del.
Silver dun results from homozygous codon deletion within the PMEL gene (p.Leu18del) PMEL del/del.

From a breeder aspect this simply means the dun trait within various Galloway populations is an autosomal incompletely dominant trait; .i.e. it only takes a single dose for partial expression on phenotype.

We have long known that dun is capable of both heterozygous and homozygous modification of expression in black (ED/ED +/del, ED/ED del/del), and in red (e/e +/del, e/e del/del).

While Dun may present in spotted (White Park) and patterned (Riggit & Brindle) Galloways, the locus is only a mutation of solid color, i.e. black or red. The presence of spotting or pattern traits has no effect on the expression of Dun. Thus, there are two common “Dun” phenotypes: Dun Black and Dun Red. Dun modifies black or red, and should be stated first in name or genomic descriptor.

With autosomal mutations of color across species, such as Agouti and Dun, both recessive and incompletely dominant, variation of color (shading) is to be expected. This as a result of “autosomal concentration”, .i.e. a sort of cumulative effect. Just as an autosomal incompletely dominant trait has distinct impact in both heterozygous and homozygous fashion, so does an autosomal recessive trait. Only in the latter it takes much observation to take note of the subtle differences presented in the heterozygous form of a recessive. Thus, all light-colored animals are not the result of Dilution genes.

Dun is dominant to black. The effect on red is more uniform. Homozygous red (e/e) animals that are also heterozygous at the Dun locus will be duns. Animals that are homozygous Dun show a more extensive reduction in pigmentation in both black (ED/ED) and red (e/e) coloration. A homozygous black Galloway (ED/ED), but also homozygous for Dun, will appear silver. On the other hand, individuals homozygous for Dun and also homozygous red (e/e) would look very light red or even yellow. Animals heterozygous or homozygous for Dun and (E+/E+) or (E+/e) will be darker than (e/e). The actual shading will vary depending upon specific combinations (zygosity).

CHOCOLATE DUN: Is likely the result of combination of Dun with various types of E and A alleles in co-expression.

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This informal article is generously provided by Alan S. Bias, and is the result of discussions in 2018
on the Galloway Cattle Genetic Discussion Group. https://www.facebook.com/groups/610010689066993

see also:
Dun Galloway Genetics ; a discussion of effect on phenotypical expression.
Paper by © Alan S. Bias; Permission granted for nonprofit reproduction or duplication
of photos and text with proper credit for learning purposes only. March 16, 2015

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About the Author: Alan S Bias is an independent researcher active in evolutionary biology as a member of Independent Academia, and has published many papers that document his research findings. In this article, he shares some of his knowlege about the genetics of the most common dilution in beef cattle. Alan is a rare Shetland Sheep, Galloway Cattle and Domestic Guppy breeder & exhibitor of 47 years. For the last 35 years he has specialized in strains known to breeders as "Swordtail Guppies". For nearly 20 years he has done cellular level research, combining formulated breeding tests & systematic observation to help breeders understand the complexities of modern Guppy genetics in the strain being produced. Alan lives in Lewisburg, West Virginia, United States. alansbias@aol.com

go home little cow
go home little cow

publisher: Vintage Publishers
published online: December 2018
featured author: Alan S. Bias