Yes Cleansweep it seems farmers sign an agreement that ‘produce grown with it does not leave the farm’.
So much for signed papers!
Dalesman, cow manure is safe from aminopyralid because it’s an expensive weedkiller that they don’t need, mainly because they make silage not hay, and silage is cut before ragwort might be much grown + their leys are recent rather than old pasture, also because they are on a tighter budget than horse owners.
I do wonder about the fear of ragwort https://friendsoftheearth.uk/nature/ragwort-poisonous-ragwort-mythbuster and whether this helps Dow to sell their horrible herbicide.
It is also in some grass mowings, not much yet as far as I can tell.