Chestnut (horse color)
Chestnut | |
---|---|
Flaxen, Liver chestnut | |
Genotype | |
Base color | Recessive extension "e" |
Modifying genes | none |
Description | reddish-brown color uniform over entire body other than markings |
Phenotype | |
Body | reddish-brown |
Head and Legs | same as body, occasionally lighter |
Mane and tail | flaxen to brown |
Skin | Usually black, may be lighter at birth in some breeds |
Eyes | Brown, eyes may be lighter at birth |
Chestnut is a
Chestnut is a very common coat color but the wide range of shades can cause confusion. The lightest chestnuts may be mistaken for
Chestnut is produced by a
Visual identification
Chestnuts can vary widely in shade and different terms are sometimes used to describe these shades, even though they are genetically indistinguishable. Collectively, these coat colors are usually called "red" by geneticists.
- A basic chestnut or "red" horse has a solid copper-reddish coat, with a mane and tail that is close to the same shade as the body coat.
- flaxenmane and tail.
- recessive mode of inheritance.[3]
- Haflingers are exclusively of this shade. It is considered desirable in other breeds, though the genetic mechanism is not fully understood. Some flaxen chestnuts can be mistaken for palominosand have been registered in palomino color registries.
- Haflingers and Belgiansare examples of mealy chestnuts. The flaxen characteristic is sometimes associated with pangaré.
Chestnut family colors
Chestnut is considered a "base color" in the discussion of equine coat color genetics. Additional coat colors based on chestnut are often described in terms of their relationship to chestnut:
- incomplete dominant cream gene. Palominos can be distinguished from chestnuts by the lack of true red tones in the coat; even the palest chestnuts have slight red tints to their hair rather than gold. The eyes of chestnuts are usually dark brown, while those of a palomino are sometimes a slightly lighter amber.[4] Some color breedregistries that promote palomino coloring have accepted flaxen chestnuts because registration is based on a physical description rather than a genetic identity.
- Cremellos have a chestnut base coat and homozygous (two copies) for the cream gene. They have a cream-colored coat, blue eyes and lightly pigmented pink skin.
- Red duns have a chestnut base coat with the dun gene (one or two copies). Their body color is pale, dusty tan shade that resembles the light undercoat color of a body-clipped chestnut but with a bold, dark dorsal stripe in dark red, a red mane, tail and legs. They may have additional primitive markings, which distinguish a red dun from a light or body-clipped chestnut.
- Gold champagnes have a chestnut base coat with the champagne gene (one or two copies). They resemble a palomino, or they may be an all-over apricot shade, but can be distinguished from other colors by amber or green eyes and lightened skin color with freckling.
- Red or "strawberry" roans have a chestnut base coat with the classic roan gene (one or two copies).
- A skewbald, "chestnut pinto" or "sorrel Paint" is a pinto horse with chestnut and white patches.
Combinations of multiple dilution genes do not always have consistent names. For example, "dunalinos" are chestnuts with both the dun gene and one copy of the cream gene.
Chestnut mimics
- Bay horses also have reddish coats, but they have a black mane, tail, legs and other point coloration. The presence of true black points, even if obscured by white markings, means that a horse is not chestnut.
- Seal brown or dark bay horses are not chestnut but may be confused with a liver chestnut. Those unfamiliar with horse coat color terminology often call most horses "brown". including chestnuts. Brown, which may be difficult to distinguish visually from dark bay, is always accompanied by black points. Liver chestnuts, in particular, are mistakenly called brown or "seal brown".
- Silver bay horses typically have chocolate- to red-brown bodies with silvered mane, tail, and legs. The flat reddish-brown color and lack of easily identified black points can confuse even knowledgeable horse persons. Silver dapple horses usually hint at black or dark gray pigment at the roots of the mane and tail, and where their silver points end on the legs. Silvers look a bit "off"-chestnut. To further confuse matters, some flaxen chestnuts have silverish streaks in their manes and tails. However, genetic testing can clarify matters.
Inheritance and expression
The chestnut or sorrel color, genetically considered "red", is caused by one of two
Because the red color is recessive, two bay or black parents can produce a chestnut foal if both carry "e" or "ea". However, two chestnut parents cannot produce a bay or black foal.
The extension
Normally MC1R would bind to the
Though "E" allows the production of black pigment, it can also allow for red pigment in some parts of the animal as seen in
See also
References
- ^ "Foal Colors". Retrieved November 30, 2021.
- ^ "General Glossary". American Quarter Horse Association. Archived from the original on July 7, 2011. Retrieved December 25, 2010.
- .
The statistical analysis of 1369 offspring from five stallions indicate, that darker shades of basic color phenotypes (dark chestnut, dark bay) follow a recessive mode of inheritance in the Franches-Montagnes horse breed.
- PMID 11736803.
The eyes and skin of palominos and buckskins are often slightly lighter than their non-dilute equivalents.
- ^ "Red Factor". UC Davis Veterinary Genetics Laboratory. Retrieved October 5, 2023.
- PMID 11086549.
Within the tested chestnut coloured horse population, no association between both alleles e respectively ea and one of the variable chestnut phenotypes could be observed. Different individuals regarding to the shade of their chestnut coat colour were found in every group of the genotypes (e/e), (e/ea) and (ea/ea).
- ^ a b Online Mendelian Inheritance in Man (OMIM): MELANOCORTIN 1 RECEPTOR; MC1R - 155555
- S2CID 29095360.
Further reading
- "Equine Coat Color Genetics". Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California, Davis.