The extension gene (E/e), or melanocortin-1 receptor, also called the eumelanin factor.
Black pigment is called eumelanin; in a 'wild-type' horse the melanocortin-1 receptor (Mc1r) is homozygous normal; the genotype is EE.
A missense mutation at Mc1r results in the inability of the horse to produce eumelanin. When the horse is heterozygous for this defect (Ee) it appears black. When it is homozygous (ee), it is red (chestnut). Other genes act on the horse's coat as well to produce the range of colours we know.
Eumelanin, expressed in genetics as E if its a copy of the dominant gene or e if it's recessive. A horse with EE or Ee in its genetic makeup will always be black-based UNLESS there is a copy of the agouti gene. A horse with ee in its genetic makeup will always be chestnut-based.
There are not two basic color genes for horses, but there are two basic pigments: red (phaeomelanin) and black (eumelanin). A horse who displays red pigment will be chestnut, and a horse who displays black pigment will be black. All horses carry both red and black pigment. Bay horses have a gene called the Agouti modifier. It pushes black pigment away from the body of the horse, leaving the mane, tail, and legs black. The three basic horse colors are black, bay, and chestnut. All other horse colors are modifications of these colors.
The two base colors for horses are chestnut and black. Both of these horses have both phaeomelanin (red pigment) and eumelanin (black pigment). The Agouti Locus pushes black pigment out to the horse's points, leaving only red pigment showing on the body. This causes bay, which is considered a third base color.
No breed of horse is exclusively black, there is one breed, the Friesian that comes in mainly black, but they also carry the gene to express red (chestnut.)The Extension gene is responsible for black and red pigment. If a horse is Homozygous (dominate) for black then it will have EE, if the horse is Heterozygous (recessive) for black it will be ee and will be chestnut in color. It is also possible for a horse to be Ee, that means it carries one copy each of black and red and can pass either one of those along resulting in either black or chestnut foals if paired with another horse that is Ee or ee.
A black and white 'spotty' horse could be any number of colors. It could be an Appaloosa or Appaloosa marked horse, or it could be a pinto marked horse depending on how big the 'spots' are and what breed or cross it may be.
Silver dilutes black pigment. Silver has no effect on Red. And a black horse carrying the silver gene will be brownish/chocolate with flaxen mane and tail.
No, Agouti is responsible for making a black horse into a bay, it affects the spread of black pigment. The gene responsible for making a chestnut into a palomino is the Cream gene, one copy of cream on a red / chestnut horse will create a palomino, two copies will create a cremello.
The three basic colors are Black, Bay, and Chestnut. Black and Chestnut are the basic colors that all horses are born with, however the Agouti gene effects the spread of black pigment (limiting it or not) Which can create a bay horse. After that other modifier genes can act on those three basic colors to create a very wide variety of colors.
a black horse with a black mane and tail is considered a black horse.
A Black horse
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The basic coat colors of chestnut, bay, brown and black horses are controlled by the interaction between two genes: Extension (gene symbol E) and Agouti (gene symbol A). The Extension gene (red factor) controls the production of red and black pigment. Agouti controls the distribution of black pigment either to a points pattern (mane, tail, lower legs, ear rims) or uniformly over the body. The effects of approximately 10 other genes may modify these pigments to provide an array of colors in the domestic horse ranging from white to black.
Black is the adjective; horse is the noun.