Strawberry roan



Strawberry roan, or chestnut roan, is a horse coat color consisting of a mixture of reddish-brown and white hairs in varying proportions, stable over the long term, with the head and lower limbs remaining darker than the rest of the body. Because of the wide variety of possible shades and seasonal variations, the horse coat has given rise to an abundance of poetic terminology, often inspired by the lexical field of botany, in both English and French.

Before the possibility of genetic recognition, the strawberry roan coat was described solely on the basis of the phenotype of the horses concerned. Its genetic function was hypothesized as early as the 1910s, with the identification of a Roan factor. Genetically, this coat color results from epistasis, the action of at least one copy of an allele of the Roan gene (Rn) on a chestnut base coat. The mutation responsible for all Roan coats, identified in 1999, is located on the KIT gene.

This coat color is mentioned in two horses imported to the American continent by Hernán Cortés, as well as in various works and traditional songs. It can occur in all breeds of horse likely to express Roan on a chestnut base coat, such as Dartmoor, Breton, Belgian, Quarter Horse and Criollo.

Terminology
The term "red roan" can refer to strawberry roan, but it is more often used to describe bay roan, leading to possible confusion. "Chestnut roan" can be used instead for less ambiguity.

Depending on the shade, a strawberry roan horse may be called lilac roan or honey roan.

In French
The National Center of Textual and Lexical Resources (CNRTL by its acronym in French) defines aubère (strawberry roan) as "[referring to a horse]: Whose coat is made up of a mixture of white and chestnut hairs". The term is found in François-Antoine Pomey's Indiculus Universalis, in Georges Guillet de Saint-George's 1678 work, in Gilles Ménage's 1694 Dictionnaire Etymologique,  and in most general dictionaries of the 19th and 20th centuries. Félix Lecoq and Edmond Lavalard note the existence of the incorrect spelling aubert in the second half of the 19th century.

In his book Les Couleurs de nos souvenirs, medieval historian Michel Pastoureau highlights the poetic aspect applied to the, historical description of horse coat colors, citing this lexical field as an example. There's also the adjective auberisé (English: flecked), to designate a variegated coat with a partially auberic hue. Historically, a large number of French nouns refer to the color of a horse coat resulting from a mixture of chestnut and white, depending on the different shades possible: "The chestnut roan has been called mille-fleurs (hypericum flower), aubère (strawberry roan), pêchard, fleur de pêcher (peach blossom), etc. The various shades of chestnut, combined with white in various proportions, give rise to a thousand varieties which it is impossible to designate by precise names, but whose particular accidents are easy to describe in the reports".

– Baron de Curnieu This color of the horse coat is compared, for example, to that of the Hypericum flower. The name péchard or mille-fleurs (hypericum flower) comes from the pinkish hue created by the mixture of red and white hairs.

The word aubère is now considered an old name, although it was retained as an equivalent when the 1999 French classification was published. The official term used by the Institut français du cheval et de l'équitation (IFCE by its acronym in French) is alezan granité. To allow genetic distinction, this coat is sometimes (rarely) referred to in English as alezan roan, firstly because the word aubère can be used to designate phenotypes of equine coats that correspond to several different genotypes, and secondly because in French, the word "rouan" historically and by default designates the only variant of the bay roan.

A light strawberry roan is said to be a hypericum flower when its white hairs are separated on a reddish-red background, distinct and "resembling a thousand and one isolated flowers". For Merche, it's the dark strawberry roan that's generally called peach blossom, while for Lavalard, it's the horse with a pinkish tint that gets this name. According to Pastoureau, the light-haired strawberry roan is called peach blossom and the dark-haired strawberry roan: lilac flower. In the 19th century, horse dealers indiscriminately gave the name pêchard to bay-based strawberry roan and roan horses.

In other languages
In Walloon, the strawberry roan coat is called blanc baïet, in German it is called fuschsschimmel or rotschimmel, and in Hungarian it is called fakó. In Wolof, it is called Jeñ, Jeñ bu weex when white dominates, and Jeñ bu xonq when red dominates.

History
In 1910, Alfred Sturtevant published a coat genetics study on a population of American carriage horses in The Biological Bulletin, in which he identified a genetic factor for roan, which he named "R"; he noted that the coat corresponding to roan chestnut was present in less than 10% of carriage horses on the streets of New York City, but that it was never identified separately. Two years later, in his article A critical examination of recent studies on color inheritance in horses, he states that the roan factor causes a mixture of white hairs with another basic color of the horse, and seems dominant in its transmission. In 1913, in his article The Inheritance of Coat Color in Horses, Edward N. Wentworth noted the existence of chestnut and black horses expressing the roan factor, and considered it probable that there also exists a chestnut roan.

Building on the work of the aforementioned authors, Sewall Wright noted in 1917 that a horse born chestnut and becoming white as it aged would be attached to the gray family, while a horse born chestnut roan would be attached to the roan.

In 1979, on the basis of birth statistics for horses expressing a roan phenotype, Harold F. Hintz and Lloyd Dale Van Vleck postulated that the gene responsible was lethal in utero in its homozygous form. Dr. Dan P. Sponenberg demonstrated the epistasis of the Roan gene with the chestnut in 1984, after crossing a Belgian bay roan stallion with several chestnut mares, resulting in some thirty bay roan foals and a single chestnut roan. In 1999, Stefan Marklund and colleagues located the mutation responsible for all roan coats on exon 19 of the KIT gene, but the causal mutation has yet to be identified.

Description
The strawberry roan coat is always described as a stable mixture of brown/red/orange and white hairs, in varying proportions. Some horses are virtually white, while others retain a very large number of colored hairs.

The manes can also be a mixture of these two colors, or just one of them. The head and extremities of the limbs are always darker than the rest of the body.

The color of the coat can vary from light to dark, depending on the number of white hairs and the shade of the chestnut, which can greatly vary the intensity and reflection of the coat. It is customary to speak of a "light strawberry roan" when white hairs are the most numerous, and of a "dark strawberry roan" when, on the contrary, red hairs are in the majority. The horse is called an "ordinary strawberry roan" when the mixture between the two coat colors is roughly equal. There is a seasonal variation in color in all horses expressing the Roan gene, but no long-term evolution as occurs with the Gray gene. Seasonal variation means that the horse is generally lighter in summer than in winter, to the point where the white may no longer be visible in the winter coat.

In foals, the presence of roaning can be verified by the color of the base of the coat, which should be white. Foals are generally born dark-colored, and only take on their definitive color around the age of two.

Visual confusion
The strawberry roan coat is often confused with other colors, especially gray on a chestnut base, bay roan and varnish roan.

Distinguishing between strawberry roan and bay roan (both due to the RN allele) can be tricky. Bay roan (formerly roan), consists of white hairs on a bay base. The total absence of black hairs in the strawberry roan coat therefore makes it possible to differentiate these two coats. Another very frequent confusion occurs between horses carrying the Roan mutation and those carrying the Gray mutation. During the graying process, horses with a chestnut base coat go through a phase in which they display a mixture of chestnut and white coats. The distinction is made on the basis of the color of the head (which remains dark in the case of the Roan gene, whereas it contains many white hairs in the case of the Gray gene) and the evolution of the coat color over the long term, as the color of gray evolves over the years over the very long term, but not according to the seasons. If you wait a year, you can see if the number of white hairs tends to increase.

Finally, it's not uncommon to confuse strawberry roan and varnish roan coats on a chestnut base. Differentiation is based on the presence of an inverted V on the varnish roan horse head, and the characteristics of the leopard complex, such as the abundance of manes (not abundant on a varnish roan), the striated hooves, the appearance of the eye (circled in white on a varnish roan coat), and above all the evolutionary aspect, with the varnish roan horse having more and more white hair as it ages.

Distribution
Strawberry roan coats are found in a great many breeds of horse, but the founding individuals and frequency of the coat are not precisely known.

Two strawberry roan horses are mentioned among the cavalry imported by the conquistador Hernán Cortés to the American Continent; one belonged to a certain Moron, from Vaimo, and the other to a certain Vaena, from La Trinidad. The Roan mutation, and hence the strawberry roan coat, is found in American Horse breeds such as the Quarter Horse, Criollo, Paso Fino, Peruvian Paso, Mustang, Nokota and American Miniature Horse.

The strawberry roan coat is also found in various draft horse breeds, including the Belgian Trait, but at a lower frequency than the bay roan. Brooklyn Supreme, a Belgian draft that probably holds the record for the world's heaviest horse, wears this coat. Ardennais can also express the various variants of roan. Among European ponies, this coat is found in the Welsh, Dartmoor and New Forest breeds.

Strawberry roan coat is almost non-existent in sport horse breeds, and is impossible in Arabians, where the Roan mutation does not exist.

Genetics
Genetically, the strawberry roan is a chestnut-based coat that has been modified by the Roan mutation, thanks to an epistasis relationship. All forms of Roan coat, including strawberry roan, are caused by this dominant allele (autosomal dominant transmission), the Roan allele. A single copy of this allele is all that's needed to express the strawberry roan coat. The Roan allele is denoted by the symbol RN (rn if absent).

The KIT gene, which plays a role in pigmentation cells, controls the expression of roan (RN) coats. The tan coat can be tested genetically.

Combination with other coat genes
Strawberry roan coat can be combined with gray; as with all gray horses, the coat will lighten to white in appearance.

Due to its location on the KIT gene, homozygous roan theoretically cannot co-exist with a number of pinto coats, such as tobiano, sabino and dominant white.

Health and pleiotropy
Little is known about the pleiotropic effects of RN. It has been suspected that the homozygous form of RN (RN/RN) is lethal, but this remains controversial since RN homozygous horses exist and are viable. The source of this error could lie in the existence of horses that are genetically roan, but whose phenotype is hardly visible. It is also possible that several causal mutations will be identified in the future.

Cultural references
Various references to strawberry roan horses can be found in the arts, heroic tales and traditional songs.

According to sinologist Françoise Aubin's translation, the Jesuit painter Giuseppe Castiglione (known as Lang Shining, 1688–1766) painted a "white strawberry roan horse adapted for mountain walking" (in Manchu, Kulkuri suru and in Mongolian, Riditu čayan). Fulanic epic tales from Mali mention a long-listed strawberry roan horse belonging to a Fulani from Djelgôdji (1705–1827).

The title of the traditional Mongolian song zaalxan sarga (TGS 126 A6) translates as "The little strawberry roan horse". Chor bard Vladimir Tannagašev (1932-2007) noted among his recorded epics Kyryk kulaš synnyg kara sar'attyg Kan-Mergen, or "Khan-Mergen (tr) to the dark strawberry roan horse of forty fathoms".

In the US, the most popular western ballad about bucking horses (wild horses) in the 1930s is The Strawberry Roan. It was composed by Curley Fletcher (1892–1954), originally under the title The Outlaw Broncho, in 1915.

Beliefs
There are various beliefs associated with the color of a horse's coat.

For Georges Guillet de Saint-George (1624–1705), in Les Arts de l'homme d'épée (1678), "their lack of sensitivity to the mouth and flanks is the reason why they are not held in high esteem, besides the fact that they are prone to losing their sight". Baron Charles-Louis-Adélaïde-Henri Mathevon de Curnieu (1811–1871), professor of equestrian science at the Haras national du Pin, considers the strawberry roan to be the least good of the horses he calls "roans", including the grullo, the chestnut, the strawberry roan, the buckskin, the bay and the sooty.

In Yakut shamanism, according to ethnologist Wenceslas Sieroszewski, it is customary to sacrifice horses with certain coat colors to specific spirits; the Dohsoun-douïah spirit is appeased by the sacrifice of a golden-strawberry roan mare with a white head; spirits in the south of the sky that harm men are appeased by the sacrifice of light-strawberry roan horses with half-white muzzles, pink nostrils and white eyes.