Here Nick is sprinkling a Magnesium Oxide powder (we call it dusting) onto the hay for the springers mob.  This helps not only protect the cows from Grass staggers (hypomagnesaemia- a deficiency of magnesium in the blood) but also Milk Fever (hypercalcaemia- a deficiency of calcium in the blood)

It's a messy job and you always end up looking like a ghost afterwards!