Zinc oxide drenching - long term dosing gives the best protection and should be started 2-3 weeks before the spore growth danger period for maximum protection. It is 80-90% effective.
Crisis dosing (treating previously non-treated animals with higher rates of zinc during danger periods only) offers less protection. It is 60% effective. Stabilisers increase the ease of mixing and drenching and allow the mixing of more concentrated drenches.