There are instances when adding medication to cattle feed is necessary (prevention or treatment of disease) or desired (improved growth and feed efficiency).  There is also concern that using medically important antibiotics (those used in human medicine) in livestock feed can contribute to antimicrobial resistance and reduce effectiveness of these antibiotics when used to treat human disease. 

The Veterinary Feed Directive (VFD) took effect on January 1, 2017.  This restricts the use of certain antibiotics in the feed or water of livestock.  It also removed any claims for these products for growth promotion and feed efficiency.  Antibiotics covered under this act must have a VFD from a veterinarian before feed can be purchased containing them.  If they are to be used in water they must be under prescription. 

Medications that do not require a VFD include ionophores (monensin and lasalocid), decoquinate, amprolium, carbadox, bacitracin, and flavomycin.  These medications are not used in human medicine. 

More information on the Veterinary Feed Directive may be found on the UK Division of Regulatory Services website at the following link:  http://www.rs.uky.edu/regulatory/feed/VetDirective.php