Lactating Holstein cows were assigned to 1 of 2 dietary iodine treatments at the Iowa State University Dairy farm. Objectives were to compare the bioavailability and production responses of an experimental product vs. an established iodine feed ingredient. The two commercial iodine sources were both fed at increasing doses. Results indicate a similar bioavailability between products and a linear increase in blood and milk iodine levels with increasing dose. Dairy producers now have the necessary information to make educated decisions on choosing dietary iodine products.