Have just bought a product called Ornithon which is a vitamin supplement you add to drinking water. The problem is it turns the water a yellow colour and the hens won't drink it. Have any members here tried this and how did you get them to drink it.
I could try removing all water till they are forced to drink it, or possibly giving a 10% recommended dosage and gradually increasing it over time.
Another option is to add this to their mash so the colour does not show.