A method of contacting the cell surfaces of livestock which are in contact with the atmosphere, with firmly divided mineral salts in airborne suspension, by confining the animal in a chamber and exposing the animal to an airstream containing the suspension. The method makes use of a chamber with a circulation fan. The chamber may take single animals or groups. Usually the chamber is a static installation but may be adopted to trailer form for treating animals during the journey or transporting the facilities in a vehicle for treating zoo animals example or bees.