Genetics of Coat Color Patterns in Cattle
this page is part of a series "Genetics of Coat Color in Cattle"
This webpage was last updated on October 20, 2012 by Sheila Schmutz, Ph.D.
The Roan Pattern
Roan is a pattern common in Shorthorn cattle and Belgian Blue Cattle wherein the animal had intermingled colored and white hairs in at least part of its body. The pattern is inherited as the heterozygous genotype. The two homozygotes are white or colored. A relatively small proportion of the the white females are sterile due to a phenomenon known as White Heifer Disease. Because both of these breeds are usually also spotted, the roan only occurs in the areas where solid colored patches would have occurred.
The heifer at the left above is an example of a roan Belgian Blue/Simmental crossbred. Note that she has white facial markings and some white spots and the roan has only occurred where the dark colored patches would normally have been. A Shorthorn roan heifer is pictured at the right.
The gene causing the roan/white/colored phenotypes is the Mast Cell Growth Factor (MGF), also called the KIT ligand (KITLG) on cattle chromosome 5. A single base pair change in this gene is the causative mutation. A diagnostic DNA test is available but is rarely needed since each phenotype is representative of a separate genotype. In rare cases, white animals are almost entirely white with only a small spot or two. To determine if they are really white, the diagnostic test could be used.
Whiteface is a pattern where most or part of the face is white againt a differently colored body. It is a common trait in Hereford and Simmental cattle or crosses with either of these breeds. The literature from breeding experiments suggests that the whiteface of these two breeds was caused by different genes. A recent paper suggests the gene causing whiteface in Herefords is the KIT oncogne on cattle chromosome 6. The mutation within this very large gene has not yet been found. Nor is it yet certain if this is the same gene causing whiteface in Simmental cattle or not.
A potential side effect of whiteface is a greater susceptibility to Cancer Eye or Bovine Squamous Cell Carcinoma. This is a rapidly progressing cancer which often begins with the nictating membrane or third eyelid. In the course of a few months, the cancer can progress so much that the front half is condemned at slaughter. "Goggles" of color around the eyes, as pictured below, is therefore considered a good thing for a cow or bull to have. The inheritance of goggles is not understood unfortunately.
Spotting is a common pattern in several cattle breeds, including Holstein and Simmental cattle. The Simmentals pictured above also all have whiteface in addition to spots on the body. White spots against a colored body are of different sizes, shapes, and placement, seemingly at random. Recently the amount of spotting on Holsteins has also been attributed to a gene a cattle chromosome 6 near KIT (the same gene as in Hereford whiteface). This random spotting, not including the face is thought to be inherited as a recessive trait.
The pattern shown in this picture is referred to as Color Sided. This is a good description because at least part of the face, legs, tail, spine and underside are all white or not colored. Some people call it lineback because a white marking extends up along the tail over most of the back of the animal. It is a pattern which occurs in Lineback cattle, as pictured above. It is sometimes also called Finchback. A colleague, Roy Crawford, suggests that Lineback and spotting together contribute to the pattern seen in many Texas Longhorn cattle.
A recent very intriguing study of color sided Belgian Blue and Brown Swiss cattle, in the labs of Michel Georges and Tosso Leeb, lead to the discovery of a new type of mutation that causes the color-sided pattern. The KIT gene order is rearranged in one of the copies in such cattle. The authors suggest that the best explanation is that a segment of DNA broke out of its original chromosome 6 and then became circular and broke open in another place before entering chromosome 29. In some cattle this even repeated itself taking part of chromosome 29 back to chromosome 6!
Others refer to the subtle pattern seen in very young Charolais cattle as lineback. This subtle whiter marking along the tail and half-way up the spine is not due to the KIT gene from preliminary work in our lab.
The pattern of spotting characteristic of Hereford cattle, as pictured above, has solid color on most of the body. White covers the face, underbelly, legs and tail switch however. In crosses involving Hereford cattle the whiteface pattern is usually transmitted to the calves, suggesting that is inherited as a dominant. The other white markings may or may not occur in the crossbred calves.
Belted is a very striking pattern in cattle in which the central portion of the torso is white in a complete "belt" or band around the middle against a dark colored front and hind end. It is a pattern which occurs in Dutch Belted cattle and in Belted Galloway cattle. The cow in the photograph above is a Belted Galloway Salers cross.
It appears to be inherited as an autosomal dominant. Animals which are heterozygous for belting, throw 50% belted calves and 50% non-belted. The gene for belting is unknown in cattle, although it appears to be the KIT gene (again!) in Hampshire pigs. Preliminary data suggests that this is not the case in cattle. In mice a mid-torso belt is caused by a mutation in a gene called Adamts20 which prevents the pigment from entering the hair. However using comparative mapping, it seems unlikely this gene would cause the belt in cattle. Furthermore the mouse belt is inherited as a recessive, not a dominant.
The belted pattern was mapped to cattle chromosome 3 by the group of Tosso Leeb in Switzerland. They studied primarily Brown Swiss, but also included some belted Galloway in their study.
This photo of Highland bulls was taken by David Pease. The bull on the left is red and the one of the left is brindle.
Brindle is a pattern of intermingled colors which are more marbled or streaked than roan. Also the two colors are black and red or yellow in brindle instead of black or red and white, as in roan. The genetic basis of this interesting pattern is not yet understood. Highland cattle, Texas Longhorn cattle, and Jersey cattle can be brindle, as are some South American breeds such as pictured above in the hide from Argentina. Highland cattle are not necessarily born brindle but can change to this pattern by 2 to 3 years of age. Berge (1949) studied this pattern in Norwegian breeds and concluded the interaction of 2 genes is needed. It appears that cattle must have an E+ allele at the MC1R gene. Cattle with an "e/e" genotype can carry brindle but not show this phenotype.
Brindle has been reported to be caused by an allele of the agouti signal peptide (ASIP) by the group of Oulmouden in France. They studied Normande cattle that were brindle. We have also studied Highland cattle, and also have this same Abr allele, however so did some non-brindle Highlands. Brindle cattle always have at least one E + allele and no E D allele.
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