In an effort to improve the efficiency of livestock production, producers have become reliant on the use of chemical growth promoting agents. Growth promoting drugs include antibacterial feed additives, antibiotic ionophores, and anabolic hormones. These drugs are usually available for over the counter purchase and are administered by the livestock producer at specific stages in the production cycle. Considerable controversy regarding the use of antibacterial and hormonal agents for livestock production purposes exists in the United States and several other countries. Presently, the use of all anabolic growth hormones in cattle has been banned by the European Economic Communities.