Icelandics, in particular, may need some copper. So that is definitely something to research. There have been conversations about it on Icelandic groups I'm on. And a breeder in our area had a necropsy done on a lamb that died. It showed severe copper deficiency. Since then, she has been adding copper to their feed and it has eliminated some problems she has had. I'm still trying to learn more about this issue, since it's the exact opposite of everything I've read about sheep. But apparently, Icelandics maybe the exception to the no copper rule.