Milk Iodine Content as Influenced by Feed Sources and Sanitizer Residues1

Abstract

Human consumption of iodine has increased to amounts which are about equal to the upper safe level as set by the National Research Council. One of the major sources for the greater iodine consumption is an increase in the amount reported in milk and other dairy products. The mammary gland does not limit the amount of iodine secreted in milk as it does with many other elements. Increased use of organic iodine in feed has resulted in high levels in milk in some dairy herds. Most of the herds with levels above 1,000 μg/liter were fed organic iodine above recommended levels as a prevention for foot rot. Iodine teat dips and udder washes can contribute additional iodine to the milk. In a few instances, the misuse of iodine sanitizers in the dairy industry has also contributed to increased milk iodine. If milk iodine levels are to be held at the present level or decreased, iodine feed supplementation and sanitizers must be used as currently recommended.