Coat Colour in Horses
Coat colour in horses is determined by a number of genes acting together. Interactions of these genes can be complex and our molecular understanding of equine coat colour genetics is still at an early stage. However, the genetic change responsible for chestnut coat colour in horses has now been identified and can be tested using DNA technology.
All horses have two copies of every gene, one copy inherited from the sire, the other from the dam. Genes exist in different forms which can have different effects - these forms are called alleles. A gene termed extension has been identified as determining whether the coat colour in horses is dark (black, brown or bay) or chestnut. For the extension gene in horses two alleles exist, given the symbols E and e . E is the dominant allele of the gene, whereas e is recessive. In horses where both alleles are E , the coat colour will be dark (black, brown or bay). This combination is conventionally written EE. In horses where both alleles are e (written as ee) , the coat colour will be chestnut. For horses with one copy of E and one copy of e (written as Ee), the coat colour will be dark (black, brown or bay), the E allele (which gives the dark colouring) being dominant over the e allele.
The progeny from an EE dam and an EE sire will always be EE, and therefore dark in colour. The progeny from an ee dam and ee sire will always be chestnut since they must be ee. However using Ee stock in a mating program can produce both dark and chestnut offspring. This is summarised in the table below.
Results for the test will be presented as no , one or two copies of the gene causing chestnut coat colour in horses. There will also be an explanation of the significance of the result for breeding.
This test requires 3-5mls EDTA blood. Samples for testing should be sent together with a completed DNA Testing form and payment of £65 inc VAT (cheque or credit card) for each sample to Genetic Services, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU.
DNA testing forms can be downloaded by clicking here .
Enquiries should be made to Symone Ingram telephone +44 (0) 8700 509144 or fax +44 (0) 8700 502461 or via e-mail to dnatesting@aht.org.uk.
