Iodine deficiency in sheep

Larry L. Berger, Ph.D.

Salt Institute

Salt and Trace Minerals newsletter

Summer 2008 (Vol. 40, No. 3)

Every continent has areas where goiter in humans and livestock has been associated with iodine deficiency. A 1928 study found that feeding salt fortified with potassium iodide would prevent goiter in farm animals and iodized salt quickly achieved widespread use. In sheep, four factors can affect the supplemental iodine requirements: 1) the amount of iodine being consumed from feed, water, soil, etc., 2) the intake of dietary constituents, called goitrogens, which interfere with the thyroid gland’s ability to trap iodine and to convert it into thyroactive substances, 3) the presence of an adequate amount of selenium is required for proper iodine metabolism, and 4) environmental factors, such as cold stress, can increase the iodine requirement, since the rate of basal metabolism must increase to maintain core body temperature.