Burin-haired horse

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Left: burin-haired fox. Right: graver-haired brown

A spiky-haired horse or color changer has a strong scattering of white hair into the colored coat due to the Roan gene (Rn). The interference is a mutation of as the dominant white color and several forms of spotting KIT - Locus returned.

Burin-haired horses are also known as iron mold , permanent mold or, if the underlying color is black, black-headed mold . Genetically, however, the color of the spiky-haired horse is completely different from the mold color . However, these color names are still widely used.

Burin-haired horses are rare. In a broader sense, all horses are referred to as spiky-haired that have individual white hairs scattered in the dark fur.

Appearance

A spiky-haired horse has white hair in its fur interspersed with the color created by its other color genes. This mainly affects the undercoat, so areas of the body with little undercoat, such as the head and legs, as well as the tail and mane, are darker than the body.

Many spiky-haired horses get lighter when they get their winter coat in autumn, as the winter coat has a particularly thick undercoat. They get darker again as soon as they get their summer coat, which has less undercoat.

Most Roan, however, show their prickly hair both in winter and in summer.

The amount of white hair strewn about can vary considerably from horse to horse, but apart from the seasonal changes, it remains the same throughout life. As a yearling, a pin-haired horse already has as many white pin-hairs as it does as a full-grown animal.

Individual stylus hairs can also appear in horses of normal color, for example in the form of a fox with stylus hair, without the horse being a real roan. A roan, however, can never be completely without prickly hair.

  • Burin-haired fox

  • also a pin-haired fox, but clearly lighter

  • Graver-haired brown

  • Graver-haired brown with clear color coding on the head

  • Graver-haired black horses or black-headed mold

genetics

This spiky lightening of the hair of a colored horse is inherited by the Roan gene . This is a mutation of the kit locus, i.e. a weakened form of leucism .

The same gene is mutated in Tobiano , the dominant white color of the horse and the Sabino check. If a horse breeds one of these four genes (that is, has the gene twice), it cannot have either of the other two genes. If it is not inherited, it can have at most two of these predispositions. The horse's extension locus is located nearby on the same chromosome , so that the fox color is often inherited together with the spiky hair color.

The prickly hairiness arises because not enough stem cells of the melanoblasts (ancestors of the dye-forming cells) migrate from the neural crest during embryonic development , so that many hair bulbs have not received any melanocytes that could produce dyes after the completion of fetal development . The hair that lacks these cells therefore remains white.

In several studies, only mixed-blood roans could be detected, i.e. cases in which only one copy of the gene is present. It is therefore assumed that pure-bred foals that received the Roan gene from both parents are not able to survive and die in the womb. The frequency of the gene is below 5% in the races in which it occurs at all. Therefore, two spiky-haired parents will rarely be paired with each other, and the lack of known pure-breeding horses can therefore also be a coincidence.

There is only one breed of horse, the Quarter Horse , where there are various stallions of the Hancock bloodline who exclusively sired spiky-haired horses and therefore had to be homozygous. But this could also be explained by the fact that this is another, as yet unknown Roan gene.

Races

In the following breeds, graver-haired horses are more common.

Possible confusion

If you use the term “spike-haired horse” in the broader sense, any other horse that has single white hairs interspersed with colored fur is also called spike-haired. Animals, which correspond to this extended definition of "prickly-haired horse", are often easily confused with it. Here they are listed with their exact names.

  • Mold : Mold foals are born dark and gradually get more and more white hair. Their heads are usually lighter than the body.
  • Rabicano : Mainly white hair sprinkled on the belly, while the head, neck, legs, shoulders and withers, as well as the hind legs up to the croup (buttocks) remain darker.
  • Varnish Roan : Only a V-shaped mark remains dark on the face, the dark color on the legs only extends to the knee and ankle.
  • Frosty Roan Apparently there is a roan gene that causes white burin hair on the horse's back, in mane and tail, as if it had snowed on the horse. The head and legs are dark, like those of the spiky-haired horse.
  • Sabino Overo The Sabino gene sometimes causes a spiky hair color, which can be quite different, but is always associated with a blaze or lantern.

See also

literature

Web links

Commons : Roan horses  - Collection of images, videos and audio files

Individual evidence

  1. ^ S. Marklund, M. Moller, K. Sandberg, L. Andersson: Close association between sequence polymorphism in the KIT gene and the roan coat color in horses. In: Mamm Genome. 10 (3), 1999 Mar, pp. 283-288. PMID 10051325 .