Copper Oxide

I have just finished reviewing a trace-mineral premix formula for an integrator who is buying his premixes from a nutrition supplier. The integrator only specifies the nutrient levels and the supplier provides the different salts mixed up in appropriate proportions along with a carrier. This is quite normal in most cases I have reviewed.   But, not for the first time, I noticed that copper oxide was used as the only source for copper in the premix. Now, it is not widely know, but it is very wel