Hormone Use In Livestock There have been many recent developments in the field of hormones. One of these has been the use of hormones in livestock. Many farmers are finding it beneficial to use hormones to help stimulate the growth of their animals as well as making the meet leaner. They also use hormone injections to induce superovulation in sheep. Porcine Somatotropin (PST) is a protein, which is naturally produced in pigs by their pituitary gland. This is responsible for growth and muscled development. New technological advancements have made it possible to manufacture PST, which is identical to the naturally produced protein. PST is po