Bovine Somatotropin (BST or BGH)

Bovine somatotropin (BST), also known as bovine growth hormone (BGH), is a hormonal product that is part of the natural process of lactation in cows. Since the 1930s, the injection of natural BGH has been used sporadically in dairy cattle to increase lactation rates to meet consumer demands for milk and other dairy products. In the 1980s, it was found that BGH could be produced synthetically, making it more readily available. This BST is referred to as rBST, or recombinant BST—reference to the recombinant DNA or genetic engineering technology used to produce it. Similarly, rBGH is used to refer to recombinant BGH. (The two terms are interchangeable.) This was one of the first uses of molecular genetic engineering, although an artificial rennet used in the making of cheese was developed at about the same time.

By the late 1990s, over 1,800 research papers on rBST had been written, reflecting intense scientific interest in genetic engineering rather than any sudden interest in dairy farming. But at the same time, controversies arose about the idea of changing the way milk is produced, and these received substantial news coverage, as did other controversial aspects of agricultural biotechnology of which this was one of the first. The use of rBST has represented a special challenge for risk communicators because of the broad range of views that exist about it. While some dairy farmers saw rBST use as a way to increase milk output (and profits), others were concerned that this practice would help larger farms win out over smaller family ones. The use of rBST [Page 98]also touched off a number of controversies over food safety and animal welfare. This entry reviews the main controversies over animal welfare, food safety, and industrial food production associated with artificial hormone use in dairy cows.