rBGH

Bovine somatotropin (bST), or bovine growth hormone (BGH), is a naturally occurring protein hormone that controls the amount of milk produced by a dairy cow. Bovine somatotropin is naturally in the milk extracted from a cow. Recombinant bovine growth hormone (rBGH), however, is a synthetic, genetically engineered version of BGH injected into a cow to artificially increase her milk production.