noun
dark bay (horse coat)
A specific term used in horse breeding and equestrian contexts to describe a dark bay coat color, where the body is dark brown and the mane, tail, and lower legs are black.
その競走馬は美しい黒鹿毛の毛並みをしている。
That racehorse has a beautiful dark bay coat.
青鹿毛 is another dark bay shade, often with a more blackish or bluish tone compared to 黒鹿毛.
Compound of 黒 (くろ, 'black') + 鹿毛 (かげ, 'bay horse color'). The term 鹿毛 itself derives from the resemblance of the coat color to that of a deer.