Recently I've hung up Rockies Zinc blocks to help our sheeps' feet, and they seem to be working. However, although the blurb says they're unaffected by rain, the reality is that they're dissolving in the wet at quite a rate. Also, they kill the grass underneath!
(Mind you, the blurb also suggests that you can smilingly turn your back on a heilan' coo and get away with it, so what do they know?
) The blocks are far too expensive to waste like this, so I need to find a way of keeping them out of the rain, but ensuring that the sheep can still get to them. Commercial holders are available, but I haven't found a design yet that weatherproofs them as well.
We have the same problem with licky buckets, which just fill with rainwater and turn into expensive sludge.
I'm sure I'll come up with something, but before I reinvent the wheel, have you already come up with a great idea that you'd be willing to share?