The Importance of Iodine
Iodine is an essential trace mineral critical for animal health, primarily due to its role in the synthesis of thyroid hormones—thyroxine (T₄) and triiodothyronine (T₃)—which regulate metabolism, growth, reproduction, and thermoregulation.
Deficiency leads to goiter (thyroid gland enlargement), reduced growth, poor fertility, impaired lactation, weakened immunity, and fetal developmental issues. Regions with iodine-deficient soils (e.g., Great Lakes and Northwest U.S., parts of Canada) pose higher risk, especially when relying on local forages.
Toxicity from excessive iodine intake (e.g., overuse of supplements) can cause iodism—marked by cough, nasal discharge, dermatitis, weight loss, and increased mortality, particularly in dairy cattle and sheep.
Optimal supplementation is key: National Research Council (NRC) recommends 0.2–0.3 ppm for dairy cattle and 0.33 ppm for beef cattle. For pigs and beef cattle, 120–250 μg/kg dry matter is advised to maintain performance and thyroid function.
Iodine is efficiently absorbed (70–80%) in the rumen and intestines and is concentrated in the thyroid, milk, and eggs—making animal-derived foods a significant source of iodine for humans.
Proper iodine management ensures animal productivity, food safety, and human nutrition.