Hi, I have the acid applicator on my br740a round baler. Unit costs about $4,500 Canadian and cropsaver/juice preservative costs about $600 for a 55 gallon drum. It allows you to bale efficiently to about 24% moisture, beyond that you end up going through too much acid. The acid burns and is a pain to pump into the reservoir 10 feet up. It also corrodes, so you need to wash up the baler after.
The bales are loved by the horses and cows alike. Absolutely no mould. I've left acid net wrapped bales in the field uncovered and opened them up in winter with no dust or mould beyond losing the outside inch. Better to stack under cover.
Anyways, worthwhile when making large amounts of hay. All large square balers use it.
I do about 400 acres of hay for horses and cattle.
If you want to know more about the additive google propionic acid.
Take care
Grant