The commonly used acronyms for the genetically engineered recombinant bovine growth hormone, which is also called recombinant bovine somatotropin. Scientists created it to replicate the naturally occurring protein hormone bovine somatotropin (bst), which is secreted by the pituitary glands of cattle, as well as human beings, dogs and other animals. The natural bST is also known as a growth hormone because it influences the metabolism of proteins, carbohydrates and lipids. The artificially produced rbGH is injected into cattle to stimulate milk production, increasing it anywhere from 10 to 40 percent. It's allowed in the United States and the European Union countries but banned in Canada. To date, there are no long-term studies to prove whether or not rbGH milk is harmful to humans, though it can produce health problems in cows. Health advocates are endeavoring to have this artificial hormone banned in the United States but those concerned about health issues should look for milk products labeled "rbGH-free" or "rbST-free."