Bovine Somatotropin: An Overview

Bovine somatotropin (bST), or bovine growth hormone, is a natural substance produced by the pituitary gland, a small structure at the base of the brain. Growth hormone is produced in all species of animals and is important for growth, development, and other body functions. In the 1930's, it was discovered that injection of bST into lactating cows resulted in a significant increase in milk production.

Until recently, the only source of bST was from the pituitary gland of slaughtered cattle. Only small, expensive quantities were available. The advent of biotechnology led to the isolation of the gene that "codes" for, or controls the production of bST. Scientists, using a technique known as recombinant DNA technology, removed the gene from the nucleus of bovine pituitary gland cells and inserted it into the acterium Escherichia coli. These genetically altered bacteria are then grown in artificial media and produce large amounts of bST which is then purified and injected into cattle. Similar recombinant DNA technology is used to produce several approved drugs, including insulin for treatment of diabetes and tissue plasminogen activator (TPA) for treatment of coronary thrombosis (heart attack) in man.

In agriculture, biotechnology has often been viewed as either a panacea for curing most problems, including the elimination of world hunger, or damned as a threat to the environment and the economic viability of the family farm. The potential licensure of bST for commercial use in dairy cattle has been controversial and has stirred heated debate by the dairy industry, activist groups, politicians, and consumers. Four commercial companies are in the process of submitting data to the Food and Drug Administration (FDA) for approval to use bST in dairy cows to increase milk production.