Posted 9/26/2009 05:00 (#860582 - in reply to #860350) Subject: Not True!
BST is a naturally occuring hormone that cows produce. It is Bovine Somatotropin.
rBST is the man-made version - originally sold under the brand name of Posilac.
Cows were/are injected with rBST to increase milk production. When cows are injected with rBST, the cows convert the rBST into BST, and that is why there is no way to test for it.
But, to be quite accurate, rBST is not naturally-occurring; BST is.