For sheep I used a commercial salt/ mineral blocks with selenium formulated for sheep. Sorry, but I don't have the label handy. The sheep would lick the blocks quite often. Interesting part is that my horses still have their same block from 10 years ago and hardly touch it. We have a quite high salt content to our soils, so I give them some vitamin/ minerals + selenium with their daily grain ration. I also add about a tablespoon of diatomatous earth (exoskeletons of diatomes...comes in 50 pound bags used as a filtering medium for swimming pools, also as bug control in grain storage elevators. Food grade is also available , but much more expensive.) to this mix for the last 30 years. I do this for internal parasite then for fly control for all classes of animals ... First their sharp edges will slice and dice the paracites in the animal's intestines, then when the diatomatous earth is then expelled in their feces, they will then slice and dice the outer skin of the fly maggots whereupon they dehydrate and die. I also use fly predators ( a small wasp about 1/8" that preys upon fly larvae only) which lay their eggs into the fly larvae then upon hatching will eat the fly maggots inside out. I virtually eliminated the fly population on our ranch.The Old Ram-Australia said:Sorry Bossroo ,I just went back to page one and see that you do use a mineral mix ........................Just out of interest what does it consist of and in what form is your selenium ?..................The selinium question is because I may have to start "dosing"our sheep to improve conception rates and growth rates..................T.O.R.