This is Onyx. He is a Percheron / QH cross who was purchased in the middle of the winter. When his owner bought him, he was black. As he shed out that first summer, he faded to a bay. He had dry brittle hooves and low stamina.
An analysis of Onyx's forage revealed what is typically seen in Vermont hay, low magnesium, zinc and copper, and high iron. Onyx was started on a balanced diet to correct these deficiencies. He no longer faded in the summer, staying a true black. and his stamina and hoof quality improved.