Cow salt and sheep salt are not the same.
I don’t know if you know this. You may have thought that we just salted our cow and our sheep with the same generic table salt, but you would be wrong. Sheep salt has to be granular, not blocked, because sheep have smooth tongues. They cannot lick the salt block to pieces like a cow can with her much rougher, stronger tongue. They will try to chew it, and, according to some sources, can break their teeth doing so. Additionally, sheep can develop copper toxicity with the levels of copper normally found in mineral blocks formulated for other species.
Since we now have both the sheep and the cow in one shade mobile, we need to make sure they are both getting salt, but not mixing it.
Since Iris, though small for a cow, is bigger than the sheep and somewhat entitled, she considers herself queen of the pasture, and especially queen of the shade mobile. She is not rough with the sheep like our highland steers were sometimes. She just walks in when she wants to and matter-of-factly eats whatever hay looks good to her, whether the sheep were there or not. They get out of her way.
Why is this significant? Because it means that when it is cold and rainy she spends most of her time in the shade mobile. The sheep salt box has to be low enough that they can get to it, which means, in effect, below the level of Iris’ butt.
Yep. More than a few times we have had to clean Iris poop out of the sheep salt.

So as soon as we had a day to get some building done, we rigged together a cover for the sheep box.

We also modified Iris’ salt box so it can sit higher than the sheep can easily reach.

And put the cow salt block in it.

Ellie took a great picture of her finger.

The cover is pretty straight forward. It just screws on to the frame of the shade mobile.

And the salt box loops onto the 2×4 underneath it.

And that should keep Iris from pooping in the sheep salt.

All the sheeps wonder if Ellie is bringing them snacks, and if not, what is she doing in their paddock.