‘Is my horse bay or brown in colour?’

A bay male

A bay horse is a dark brownish-red, except for its muzzle, mane, tail and legs, and the tips of its ears, which are all black. Unless it has white leg markings, the hooves are also black.

The black markings on a bay horse are known as ‘points’, and all true bays have black points.

A brown horse is usually a dark seal colour over its whole body. Few brown horses have black points, and many have a lighter brown muzzle than the colour that dominates its body. Brown horses also have black hooves, and both brown and bay horses can have brown or black skin (except where they have white markings on their faces or legs).

Understanding the genes
The genetics of a bay are far simpler than those of a brown horse. Chestnut horses carry a double dose of the recessive e gene that codes for a red coat.

The dominant E gene, found in black horses, genetically codes for a black coat with underlying black skin.

A horse with a double dose of the dominant E gene will be black. All bays carry at least one dominant E gene, but this is modified by the dominant agouti gene (A), which suppresses the black colour, so that it appears only in the points.

All chestnut horses are a reddish-gold colour, but their legs, manes and tails are the same colour as their bodies. The genetics of a chestnut horse are recessive for both the e and a genes. This can be written as aaee.

A bay horse must have at least one A and one E gene (the dominant form of the agouti and the black gene). So the bay horse can be Aa or AA, EE or Ee. If the horse has the genetics aaEe or aaEE, it will be brown or black respectively.

In the days before modern genetics, breeders recognised that if you mated a bay horse with a bay horse you occasionally ended up with a chestnut foal (aaee) and, very rarely, a brown or black foal. This was especially true with English Thoroughbreds, which were mainly bay with a few chestnuts and an occasional black or grey.

In contrast to bays, brown horses are complicated, as the colour does not always reflect their genetics. Some brown horses are simply very dark bays and have black points.

Others are genetically black (EE) and only look brown due to an unbalanced diet or sun bleaching. Still others may be very dark chestnut.

Predicting colour

Horse genetics have advanced considerably over the past 20 years. Owners can now send the hair or blood of their breeding horses for colour evaluation to the Onderstepoort Veterinary Genetics Laboratory in Pretoria North. Information on submission of samples is available at up.ac.za.

If you already know the genetic colour of your horse, some Internet sites calculate the probability of the colour of the foal from the colour of the parents. A useful site is animalgenetics.us

Dr Mac is a veterinarian and an academic, and a stud owner. 

The post ‘Is my horse bay or brown in colour?’ appeared first on Farmer's Weekly.


Leave a Reply

  • Get our news delivered, click the checkbox to join.

  • current category

    chronological order


    Bob the Robot Office by Studio Joanna Laajisto, Helsinki, Finland

    We love it when designers flex their creative muscles in the transformation of spaces from one use to another. New and shiny is great, but there’s always something uniquely compelling and fascinating about an environment that has a history. Reuse and repurposing took many forms in the case of the office for Helsinki, Finland-based creative […]
    The post Bob the Robot Office by Studio Joanna Laajisto, Helsinki, Finland appeared first on The Cool Hunter. http://thecoolhunter.net/bob-robot-office-studio-joanna-laajisto-helsinki-finland/…

    Read More »

    Amalfi Print – Chris Ngu

    The Amalfi coast print has been delicately captured in this photo by UK photographer Chris Ngu with warm golden pink morning light gently illuminating the small picturesque city clinging onto its steep rocky platform. This stretch of sun-kissed coast in Italy’s Campania region has understandably enchanted visitors for centuries with its sublime natural beauty enhanced […]
    The post Amalfi Print – Chris Ngu appeared first on The Cool Hunter. http://thecoolhunter.net/amalfi-print-chris-ngu/…

    Read More »

    First Boutique of Japanese cosmetics Brand EN, Paris, France

    How far can you push a retail concept and still keep it real? We think Paris-based Archiee  has pushed their concept for the first boutique of a new Japanese cosmetics brand en  to just that edge: As far as you can go but not too far. What saves the new en store, located in an […]
    The post First Boutique of Japanese cosmetics Brand EN, Paris, France appeared first on The Cool Hunter. http://thecoolhunter.net/first-boutique-japanese-cosmetics-brand-en-paris-france/…

    Read More »
    Farmer's Weekly

    Why arthritis treatments are controversial

    There are various treatments available for equine osteoarthritis. However, these are mainly palliative and do not promote healing, says Dr Mac. https://www.farmersweekly.co.za/animals/horses/arthritis-treatments-controversial/…

    Read More »

    Private Wine Cellar, Rasų Park, Vilnius, Lithuania

    Those of us who see thousands of design and architecture projects each month are not easily impressed as we tend to see the same ideas over and over. So, it is an exceptional delight when we see something that actually stops us and impresses in its visual impact and impeccable execution. We suspect that even […]

    The post Private Wine Cellar, Rasų Park, Vilnius, Lithuania appeared first on The Cool Hunter.

    Read More »