In summary , unless a horse has at least one functional E-allele , it can not be bay .
Such horses , having two copies of the recessive mutation , have eumelanin - free , phaeomelanin - rich coats ; they are red , or chestnut .
In summary , unless a horse has at least one functional E-allele , it can not be bay .
Such horses , having two copies of the recessive mutation , have eumelanin - free , phaeomelanin - rich coats ; they are red , or chestnut .