dairy blend for ducks

[Stamper]

A local place here can get me a bulk organic feed for a really great price. I went in today to go over the details and I kind of left with more questions. They specialize in dairy feed and they do a custom dairy blend. They have a PVM (protein, vitamin, mineral) pellet that is min 18% protein and they have a grain pellet and a rolled grain mix. I can do just the PVMs or I can do any kind of blend that I want (which would lower the protein. I have the list of all the vitamins and minerals that are added but I don't have the amounts. There are no B vitamins, so I know I would have to add those. I know that there is also copper (which can be toxic for sheep) and I don't know if it's ok. My friend has been feeding her ducks the "dairy blend" which is only 12% protein, which I know is too low, but the ducks seem to be fine. I know that it could catch up to them though. So I would definitely go for a higher protein blend but I don't know what else I should worry about.... any ideas?

Also, what is a good way to supplement the B vitamins? Crushed tablets??

Thank you so much!