What is rbST?

rbST is the acronym for recombinant bovine somatotropin, a synthetic version of a protein hormone that is produced naturally in the pituitary glands of all cattle, including dairy cows. rbST is used to stimulate milk production in dairy cows. According to the U.S. Food & Drug Administration, there is no difference between milk from cows treated with rbST, and milk from those that haven't been treated. Challenge Butter products—Challenge Butter and Challenge Unsalted Butter in the 1-pound, ½-pound, and Whipped sizes are rBST-free.