Farm Table says:
This webpage was produced by DairyNZ and describes milk fever in dairy cows, its prevention and supplementation methods to reduce the risk of milk fever.
It details magnesium supplementation pre-calving, starting two to three weeks prior to calving, the different magnesium compounds that can be used (sulphate, chloride, oxide) and how to use them. The webpage also includes tables on dietary magnesium concentrations and quantity of supplementary magnesium required for different breeds and quantities of magnesium sources to supply the required amounts of pure magnesium.
There’s also a link to a factsheet on magnesium supplementation that provides more detailed information on methods of supplementation in particular.
In conclusion, this webpage will assist in understanding your milking herd’s required magnesium as a percentage of diet and techniques to increase the intake to prevent reduce the risk of milk fever due to calcium deficiency.