Bay is the color of horsehair hair, characterized by reddish-brown body color with black mane, tail, ears, and lower legs. Bay is one of the most common feather colors in many horse races.
The black area of ​​the bay horse hair coat is called the "black dot", and without them, the horse can not be a bay. Black dots are sometimes covered by white marks; But the mark does not change the classification of horses as "bay". Bay horses have dark skin, except under a white mark - where the skin is pink. Genetically, the bay occurs when a horse carries the Agouti gene and the black base coat. The addition of other genes creates many additional feather colors. While the basic concept behind bay staining is quite simple, the genes themselves and the mechanisms that cause color variations in the bay family are complex and, at times, disputed. The dark bay image genetics is still under investigation. The DNA test says to detect the brown seal (A t ) allele developed, but later withdrawn from the market. Disgusting genetics also appears to be skimming some horse's pony coats, and the genetic mechanism is not fully understood.
Video Bay (horse)
Variasi warna dan terminologi
Bay horses range in color from red copper light, to rich red bay blood (the most famous varieties of horse bay) to a very dark red or brown called dark bay mahogany, black-bay, or brown (sometimes "brown seal"). The dark brown shades are called in other languages ​​with words that mean "black-and-brown." Dark/dark brown may be very dark to have a nearly black mantle, with brownish red hair only visible under the eyes, around the muzzle, behind the elbow, and in front of the stifle. Dark bay should not be confused with chestnut "Hearts", which is also a very dark brown color, but liver chestnuts have brown mane, tail and legs, and no black dots.
The pigments in the horse's cloak, regardless of shade, are rich and fully saturated. This makes the bay very shiny in the sun if treated properly. Some horse balls show dappling, caused by textured and concentric rings inside the mantle. Dappling on horse bay shows good condition and care, although many well maintained horses never wet the bed. The tendency to be sleepy also, to some extent, is genetic.
Bays often have two-color hair shafts, which if shaved too close (like when cutting the body to a horse show), can cause the horse to appear some lighter colors, a rather dull orange gold, almost like a dun. However, as the hair grows, it will darken again to the right color. This phenomenon is part of the genetics of bay colors, but is usually not seen in darker bay colors because there is less red in the hair shaft. ( View: "Inheritance and expression," under )
There are many terms used to describe the particular nuances and qualities of the mantle of the bay. Some color variations can be attributed to nutrition and care, but most seem to be due to inheritance factors that are not yet fully understood.
The most pale shades, which do not have specific English terminology found in other languages, are called wild bay. Wild bays are the correct bays with completely pigmented feather color and black mane and tail, but the black dots only extend to the pastern or fetlock. Wildcat is often found along with the so-called "pangare" that produces a pale color on the lower abdomen and soft areas, such as near the stifle and around the muzzle.
The bay horse has dark skin and dark eyes, except the skin under the sign, which is pink. Skin color can help an observer distinguish between a bay horse with a white mark and a horse that resembles a bay but does not.
Ambiguity "brown"
Some breed registrations (including the Jockey Club Thoroughbred registry) use the term "brown" to describe dark bay. However, the "heart" chestnut, a horse with a red or brown tailed or tailed mane and a dark brown coat, is sometimes also called "brown" in some contexts. Therefore, "chocolate" can be an ambiguous term to describe the color of horsehair. It is clearer to refer to dark-colored horses as dark coves or chestnuts of the heart.
However, to complicate matters, genetics that lead to darker coat colors are also being studied, and there is more than one genetic mechanism that darkens the color of the feathers. One of them is the sooty gene theorizing that produces a dark color on every color of the fur. The other is Agouti specific allele associated with certain dark bay types, called chocolate seals. The brown horse seal has a dark brown body and a lighter area around the eyes, snout, and pelvis. A DNA test says to detect the brown seal (A t ) allele developed, but the test was never reviewed by peer review and because unreliable results were later withdrawn from the market.
Influence of gray genes
Some foals are born bays, but carry the dominant genes to whiten, and thus will turn gray as they mature until finally their hair coat is completely white. Children who are going to be gray must have a gray parent. Some foals may be born with some white hair already visible around the eyes, snout, and other fine-haired areas, but others may show no signs of gray until they are several months old.
Maps Bay (horse)
Color confused with bay
- Chestnuts, sometimes called "Sorrels," have a reddish body coat similar to a bay, but no black dots. Their legs and ears have the same color as other body parts (except they have white marks) and their manes and tails are the same color as their body colors or even some brighter colors.
- Black is sometimes confused with dark coves and chestnut hearts because some black horses are "sunburned," that is, when they are dried, they develop a brownish coat, especially in fine-haired areas around the sides. However, the original black color can be identified by looking at the fine hairs around the muzzle and eyes. These hairs are always black on black horses, but they are reddish, brownish, or even golden glow in the bay or chestnut.
Family colors
Traditionally, bay is considered to be one of the "hard" or "base" feathers of a horse, although it is genetically a simple basic base color, based on the presence of an extension gene, ("E" or "e") is chestnut and black. Bay is the result of an agouti gene that acts on a black base layer. The additional effects of the horseflesh genes on the bay template change the base color to nuance or other patterns:
- The buckskin horses have black mane and tail, but instead of a red or brown coat, they have a cream or a gold coat. Although once called the "Sandy" bay in the old text on horse color, the genetic differences created by cream genes are significant. They are horse bay which is also heterozygous for dominant creme alleles (CCr). The black pigment remains largely unchanged, but all the red pigments in the mantle are diluted to gold. Buckskins are rarely mistaken for the bay because their coats are significantly brighter and have no red or orange color.
- Perlinos is a homozygous horse bay for the dominant creme allele (CCr). Both black and red pigments are diluted for some beige colors, although previous black dots often have stronger reddish casts. Pink pigmented skin and blue eyes.
- Bay duns are horse bays with at least one dominant allele. The red and black pigments on the extremities remain largely unchanged, but on the body, the black pigment is diluted to slate and the red pigment is diluted to a more dusty color. The effect is similar to deer's skin, but the bay dun's coat is flat brown rather than bronze, and all duns have some form of primitive marks that include dorsal lines along the spine, and occasionally fainting horizontal strips on the back of the forefoot.
- Amber champagne refers to a horse bay with at least one dominant champagne allele. The black pigment is diluted to warm brown and red pigment to gold. The effect is similar to deer's skin, but the dots of yellow champagne do not stay black, and the skin is mottled. The Amber champagne also has brown eyes instead of chocolate.
- The silver bay is a horse bay with at least one dominant silver allele (Z). The red pigment is not affected, but the black pigment in the short coat is diluted to dark, flat, grayish brown while longer hair is diluted to silver. The overall effect on a bay is a brown horse with a pale mane and tail.
- Bay Roan horse is paid with at least one dominant allele (Rn). Gen roan creates a white hair effect mixed with a red body coat. This color was previously united with chestnut or "strawberry" chestnut and was called "red roan."
- The bay of pintos is a horse bay with a number of white spot genes, including but not limited to tobiano, overo frame or splatter white, and so on. The pattern has nothing to do with whether the horse is a bay or not. The pinto horse may also have a base bay coat lined with white spots. Sometimes the term "skewbald" or "tricolor" is used, especially in the UK, to call bay pintos.
- Sabino is a color pattern in a pinto family, but in some cases, the gene may be expressed minimally in the form of a very thick white mark or a slight spotting of the body and such horses will be registered by the owner as "bay," especially in a breed registry that has no category for pinto.
- Bay Leopards are horses carrying leopard genes (Lp) or complex gene characteristics from Appaloosa and other breeds. This gene also produces secondary characteristics that include dappled skin, white sclera around the eyes, and striped nails.
- Some horse bays can carry the rabicano gene, which produces faint fainting only on some parts of the body or may cause some white feathers or creams to appear on the mane or tail, sometimes creating a "skunk" effect. Most bays with rabicano are listed as bays or as bay roans.
Genetics
Different shades of the bay may be genetically produced by many factors, but a simple explanation of the genetics of the bay is the "red" color, seen on the chestnut horse, represented by the "e" recessive allele; and black, represented by the dominant "E" allele, are the two most basic color mantle genes. All other colors are produced by additional allele actions that work on these two basic colors.
A horse bay carries both Extension (E) alleles and the suppressor gene known as the agouti (A) gene. The agouti gene, dominant over the black gene, limits or suppresses black coloration to black dots, allowing the underlying red fur color. to come. Unlike other "dot" staining types, as seen in Siamese cats, the black characteristics of bay staining are not produced by dilution or gene albinism.
Since the extension genes E and agouti (A) can be heterozygous or homozygous, the extent to which the bay passes its color varies greatly from one horse to another depending on the genotype and its partner. Also, chestnut can carry the Agouti gene, which will "mask" or not manifest until the horse is bred into a horse with E allele and produce offspring with both genes.
Inheritance and expression
The bay family of mantle colors depends on two simple autosomal dominant genes: Extension and Agouti. The role of the Extension gene is to produce a protein called Melanocortin 1 receptor or Mc1r . Mc1r allows the eumelanin black pigment to form in the hair. Closely related to this process, the role of the Agouti gene is to produce Agouti signaling peptides Asip , which disables Mc1r , effectively enabling red pigment phaeomelanin to "show through." However, this deactivation does not occur throughout the mantle; it only occurs in the pulses in the body mantle and not at all on the extremities or the points .
If the horse does not have a dominant copy, dominant of the E-allele wildtype at the Extension locus, then Mc1r can not be produced. Without this protein, black pigment eumelanin can not form in the hair. Such horses, having two copies of a recessive mutation, have a rich eumelanin, phaeomelanin-rich coat; they are red, or brown. In short, unless a horse has at least one functional E-allele, it can not be a bay.
Similarly, if the horse does not have a functional dominant copy of the A-allele in the Agouti locus, then Asip can not be produced. Without Asip , the eumelanin is unregulated and the mantle completely black. The black pigment rule, though, depends on its presence in the first place; a horse with a recessive Agouti genotype can not be distinguished from other genotypes in a horse with a free eumelanin coat. When eumelanin is present, it is limited in varying degrees with the action Asip .
Action Asip can be observed on horses that have their winter coats cut off. When shaved close, the black tip is shaved leaving the base of the phaeomelanic base. This results in a dull orange-gold appearance on the missing body coat with a spring shed. It's usually not visible in the dark bay, which has a slight red in the hair shaft.
Agouti
The causes behind the nuances of the bay, especially the genetic factors responsible for the wild bay and brown seal, have been contested for over 50 years. In 1951, the zoologist Miguel Odriozola published "A los colores del caballo" where he suggested four possible alleles for the "A" gene. He describes the order of domination between the allele and related phenotype:
- a , the least dominant, should be homozygous to be observed and responsible for an iridescent black coat (non-agouti black),
- A t , only visible in the form of homozygous or when paired with a , responsible for the seal of black-brown chocolate coat, li>
- A , seen when homozygous or when paired with a or A t bay,
- A , dominant, responsible for the wildtype wild bay coat.
This was accepted until the 1990s, when new theories became popular. The new theory suggests that the bay's shadow is caused by many different genes, some of which lighten the mantle, some of which darken it. This theory also states that the brown seal is a dark horse with a property called pangare . PangarÃÆ' Â © is an ancestral feature also called "mealy", which describes the soft or communicative parts of the horse in a tan buff.
The combination of black and pangarÃÆ'Â © was terminated as a cause of chocolate in 2001, when the French research team published Mutation in agouti (ASIP), extension (MC1R), and chocolate locus (TYRP1) and their association to coat the color phenotype on horses ( Equus caballus) . This study used DNA tests to identify the recessive allele a at the Agouti locus, and found that no horse fitted with the brown seal phenotype was homozygous for the allele a .
Since 2001, the variation mechanisms in the "bay" category remain unclear. Ongoing research suggests that Odriozola's theory may be correct, evidenced by parallel conditions in rats. Rats have more than six alleles in the Agouti locus, including A t which produces black-and-brown.
Still possible to some extent, the "shade" of feather color can be managed by unrelated genes for properties such as "soot", and that the phenotypes of the palm or dark/brown browns may overlap.
See also
- Combine the mantle color genetics
- White horsehair
References
- "Introduction to Coat Color Genetics" from Animal Genetics Laboratory, School of Veterinary Medicine, University of California, Davis. Website accessed January 12, 2008
External links
Source of the article : Wikipedia
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