Provides concentrated levels of thiamine, an essential B vitamin, and magnesium. In hard-working horses or those on high-grain diets, production of thiamine by intestinal bacteria may be reduced because of stress and hindgut acidosis. Thiamine plays a vital role in carbohydrate metabolism and nerve transmission. Magnesium is needed by horses for proper synthesis of protein and digestion of starches, and its presence is necessary for hundred of enzymatic functions. When the levels of thiamine and magnesium fall below essential levels, horses may not perform their best.