For free-choice livestock feeding in feedlots, and on pastures and ranges where grain, forage and water is often deficient in sodium chloride and iodine. Lactating animals require further supplements due to excretion in milk. Chronic iodine deficiency causes goiter, sluggishness, acute sensitivity to heat and cold, stunted growth, and poor hair or wool development. Fortified with nutritional iodine provided by calcium periodate, which is water insoluble and does not leach from blocks exposed to high humidity or rain. When ingested by animals, it is readily solubilized by rumen microbial action or by stomach acidity. For all classes of Cattle, Sheep, and Horses.