Iodine is an important trace element. Iodine deficiency can occur in areas where the water and feed are deficient in iodine. Goitrogenic (producing goitre) feeds such as brassicas (e.g. rape, kale, turnips, cabbage) will aggravate a deficiency. Star grass and clover can cause an indirect iodine deficiency through the production of cyanogens.
Iodine should be dispersed throughout troughs because iodine in large quantities is extremely toxic.