Sheep are very efficient at absorbing Copper from their diet; however the problem is that they do not excrete excess copper very well. What happens is they gradually accumulate the excess in the liver. When the liver becomes “saturated” it is released and kills the animal. The levels can accumulate gradually or quickly depending on how much copper is being consumed.
When feeding sheep prepared feeds ensure there is no added copper in the diet. Cattle or goat feeds cannot be fed to sheep as these feeds have additional copper added.
We have seen cases where graziers have fed a cattle diet/supplement for winter and not seen a problem in the first year but the following year they feed the same product again and see their sheep start dying from copper toxicity. The sheep had accumulated copper in the first season but this was not enough to cause toxicity but the following season they started to accumulate copper again and when it reached the critical level the sheep start to die.
The only proviso is if you are in a known copper deficient area you should consult your veterinarian as to the best way to supplement copper. There are a variety of ways from injection, rumen slow release capsules to prepared feeds.