Hormones and Milk
Milk is a natural animal product and as such, contains some naturally-occurring hormones just like all other animal products. rBST is a synthetic version of a natural hormone found in dairy cows (bST), so some – NOT all – dairy farmers give their cows extra hormones to help them produce more milk for longer after they have a calf.
Milk and other products from cows treated with rBST has been found safe for human consumption by the National Institutes of Health, the Joint World Health Organization/Food and Agriculture Organization Committee, the American Medical Association and the American Dietetic Association.
Nutritionally, milk from cows that were given rBST is the same as organic and conventional, non-rBST treated milk.
Western Dairy Blog