Genetics of Pale Coat Colors in Cattle
this page is part of a series "Genetics of Coat Color in Cattle"
This webpage was last updated on August 16, 2008 by Sheila Schmutz sheila.schmutz@usask.ca
The bull above represents perhaps the most common white breed in Europe and North America, the Charolais. There are white cattle of many types and breeds however.
The gene or genes causing white have not all been discovered yet. White, as in the Charolais is actually caused by an epistatic or masking gene. This bull is actually red, ee but is not showing its red because of the effects of some other gene, common to Charolais. When this Charolais allele occurs in homozygous form, the animal is white. When it is only heterozygous, as in a Black Aberdeen Angus X Charolais calf the color is closer to grey or "smoke".
White Shorthorn cattle, such as the cow pictured above is part of the Roan series of alleles (see more below). The white in this case is only present in the homozygous condition with the heterozygote being roan and the other homozygote being red.
White cattle, such as White Galloway cattle are quite different from Charolais in that they have black noses and ears. This white is inherited as an autosomal dominant. Heterozygotes are not dilutions of another color but just as white as homozygotes. Their noses and ears can be either black or red or dun. Their underlying skin can be black or red or spotted. The White Galloway cow above is shown with a calf that did not inherit perfect white markings. White Park cattle, below, are similarly marked. Although an old breed, from the time of the Druids, they are now quite rare.
The colors of the points in White Galloway can be black or red which is determined by the MC1r gene, described above, or dun, for which the gene is not yet determined.
The white body color with colored points is caused by the tyrosinase gene based on data collected by Barbara Schmidtz for her Master's degree. Similar patterns exist in the mouse, Himalyan rabbit and the Siamese cat and also are caused by mutations at tyrosinase.
Some people think of albino when they hear white. The calf above is an albino and she has no pigment production at all, even in her eyes, which are pink. This is also called oculocutaneous albinism. This type of albinism occurs rarely but can be present in various breeds and has even occurred in Bison.
This Braunvieh calf, Snowdrop, has a mutation in her tyrosinase gene which renders it dysfunctional. This gene is the cause of several forms of albinsim in other animals and humans. She has a normal TYRP1 gene sequence, another gene causing albinism in humans. Both of her parents were of normal coat coloration and therefore we presume this albinism is a recessive, as are most forms of albinism in most species. A recessive form of albinisim was reported in Brown Swiss or Braunvieh cattle since 1934 at a very low freuency.
Note that another albino calf, a Holstein, did not have this mutation. Her albinism is either caused by another gene, such a P, or by a different mutation in tyrosinase.
The two bulls shown above are purebred Simmentals. The yellow bull on the left is a diluted ee or red animal. The mouse colored bull at the right is a diluted black EDe bull.
Yellow or Pale Brown "mouse" coat colors are believed to be caused by a Diluter gene (D) or genes. The identity of the gene or genes is not yet known. D is a diluter gene where DD=dark, Dd=medium color, and dd=pale color. It appears that there is more than one diluter gene, as previous researchers have suggested in the past. One gene dilutes only the phaeomelanin pigments which cause red to yellow and another gene dilutes the eumelanin pigments which cause black to brown. There could be a third gene which dilutes both phaeomelanin and eumelanin and is common in Charolais cattle.
In 2003, MATP or "underwhite" was found to be the gene causing palamino in buckskin in horses. One copy dilutes a sorrel to palamino and two copies to cremello. All these horses are producing only phaeomelanin. On the other hand a bay is producing eumelanin also which is evident in its mane and tail. One copy of this MATP mutation in a horse that also produces eumelanin results in a buckskin and two in a perlino. We have done a small experiment using markers near this gene in cattle and did not find that this gene fit as a diluter gene in cattle.
This Highland calf photo was taken by David Pease.
Dun is the name given to a pale color in cattle such as Galloway or Highland. In Galloway cattle, Dun is dominant to black. Silver dun is the color resulting when Galloway cattle are homozygous for this allele. The gene causing this coloration is not yet known. However, it is not MC1r based on sequence analysis of both dun Galloway and Dexter cattle. The Galloway heifer, below, is also called dun and is colored similarly to the Highland, above. Note that both dun animals have black noses.
In Dexter cattle, there are black and red ones and then others that are called dun. The dun colors really seem to range from brown to yellow and are inherited as a recessive trait. The photos below and data for the above statements were provided by John Potter. This color is due to a different gene than the color called dun in Galloway cattle or Highland cattle. We have recently developed a carrier test for this mutation in the TYRP1 gene.
for further information contact:
Sheila M. Schmutz, Ph.D., Professor
Saskatoon, Canada S7N 5A8
e-mail
sheila.schmutz@usask.ca