An equine oat-balancing feed supplement comprising a mix of substances including lysine, iodine, copper, magnesium, zinc and calcium is provided. The supplement further includes one or more of Folic Acid, Nicotinic Acid, Pantothenic Acid, Thiamine, Riboflavin, Pyridoxine, Biotin, Cobalt, Selenium, Methionine, Threosine, Choline, Iron, Manganese, an inert material such as cereal wheat and Vitamins A, B.sub.12, D, C, E, K. The oat-balancing feed supplement is administered to horses in an amount dependent on the age of the animal, together with an oat-based diet. The health and condition of horses has been found to improve an commencement of the intake of the supplement and in particular, racing horses have been observed to have improved performance at races when on the supplement.