Yes pretty sandy soil. It was grown a few hours from where I live. I anticipate this next batch of hay I have will be higher iron. It’s local and we are much more clay based.
I would base your copper and zinc needs then on the new batch of hay as you’ll likely have more iron and less cu/zn in it
I have had good luck switching to zinc oxide spray. It creates the barrier without the mess of the cream. Plus it is a white spray, makes her white legs extra white I start using before the mud starts as a preventative measure.
Good to know! As usual thank you so much for sharing your wealth of knowledge! I really appreciate the help