Oooops, just written a post, made a typing error, pressed back space to correct it and the post disappeared!! Will try again - what I was asking was if the vet confirms that something is missing (eg copper) then is it possible to spray those fields to be used for hay with a copper substitute? Hope you can understand this as I'm going to post before it disappears too. lol!
I really don't know if you can add copper to the pasture; but you can put out supplement that contains copper. In the US, we have loose mineral, mineral blocks and mineral tubs; so their are ways to ensure the animal gets the minerals they need, because the forage is deficient. Once, we know what we are dealing with, we can formulate a plan. Since the vet suspects copper deficiency, we've already started by getting loose mineral and then mineral blocks. Don't know if it's the deficiency or because it's something new, but the cows have just blown through the mineral we already gave them. We put out the loose, as we bought that first, and they went through what we put out overnight; it came to about a pound per head (feeding rate is like 3oz daily, likely to decrease when minerals are leveled out). Then, we put out block, and that took a couple days or more; blocks slow down consumption. Unlike horses, that are suspicious of new feed ingredients; unless they are absolutely nasty, adult cows will eat just about anything you put in front of them (calves are a bit more difficult, but they are young and still learning about solid food).
