What is rBST or rBGH?
Bovine somatotropin (BST) is a protein hormone naturally produced in the pituitary glands of cattle. Monsanto developed a recombinant version, rBST, by using a genetically engineered E. coli bacteria. Sold under the brand name Posilac, it is injected into cows to boost milk output in the short term. This practice is coming under increasing scrutiny. rBST is also known as rBGH (recombinant Bovine Growth Hormone).