Bay (color)

Bay is a color of the hair coats of horses, characterized by a body color of dark red (known as blood bay) to deep brown, with black points (mane, tail, lower legs, and sometimes the muzzle and tip of the ears). Bay is a favorite color among ranchers and horse enthusiasts.

The genetics behind bay coloring

This color is caused by the Agouti gene on one of the two base colors of horses: red (chestnut coloring) and black. The agouti gene on black restricts the black coloring to the points (see above), creating the bay color. Red is not changed by the agouti gene (so red coats with the agouti gene stay exactly the same: red), but red horses can still be carriers of the agouti gene, and thus produce bay foals from black horses.