Approximately half of the iodine in the body is located in the thyroid gland, which produces important hormones, such as thyroxin. Thyroxin, which contains 65% iodine, has a regulating effect on body metabolism. Thyroxin is involved in regulation of basal metabolic rate, temperature regulation, growth & development, neuromuscular function & reproduction. Iodine absorption is regulated by the body to some extent, but can be toxic. Iodine is well absorbed in any of its soluble forms from all levels of the gastrointestinal tract.

Iodine deficiency causes birth of weak and deformed offspring failing to survive, abortion, infertility, anestrus, reduced conception in all species, and other reproductive problems. Severe iodine deficiency results in goiter or lumpy jaw, high incidence of stillbirths, hairless pigs and wool-less lambs at birth.