The substance, one of the first applications of genetic engineering to make its way into food production, is a synthetic version of a natural cow hormone called bovine somatotropin, or BST.

• 这种激素刺激奶牛生产的牛奶是最初采用基因工程手段得到的食用产品。该激素是人工合成的天然牛激素，称作bovinesomatotropin，简称BST。