Medicated mineral mixes have been useful in reducing the risk of anaplasmosis on Oklahoma ranches.  Anaplasmosis is an infectious disease of cattle caused by a blood-born organism.  Chlortetracycline (CTC) consumed at the rate of 0.5 mg / lb. body weight daily during tick and horse fly seasons will help prevent transmission of anaplasmosis.  CTC may be administered in medicated feed; salt-mineral mixes offered free choice, and medicated blocks.   Aureomycin-90^TM is often the pre-mix that is added to mineral mixes to supply the CTC.  Adding 90 pounds of Aureomycin-90^TM per ton of mineral mix would be appropriate for 1000 pound cows.  Adding 110 pounds of the pre-mix per ton of mineral would be necessary for 1200 pound cows.  In both of these instances, the expected daily intake of the mineral is 2 ounces per head.  It is imperative that consumption levels are monitored.    Effectiveness of the medicated mineral is dependent on proper intake.   Adjustments in the amount of CTC added per ton may be necessary if different levels of intake are expected.  If you suspect cattle in your herd have anaplasmosis, your veterinarian should definitively diagnose the disease and provide you with additional information to assist in treatment and prevention.  Note: Aureomycin ^TM is manufactured by Alpharma Animal Health.