I have used two different types of multivitiamins. One is a pig and poultry powdered vitamin available from a feed store or some larger pet stores may carry something like it. I have also years ago used a fluid for caged birds when I had only a small number of birds.
I use Nutridrench that I get from our local feed store. It is a multi-vitamin and immune system booster designed for poultry. I pour a little in their peas, they seem to like it.http://www.enasco.com/product/C28059N
You are quite welcome. I have one female call duck and MicroDuck that seem to get "weak" fairly frequently. The female's symptom was dragging her self along on her belly first before finally getting on her fee. After asking ?'s on here and researching, everyone concluded it was probably due to a nutritional deficiency or malabsorption of nutrients. I started using Nutri-drench on a regular basis and the problem has disappeared. I like this stuff alot.
I usually give the ducks and geese peas (sometimes tomatoes and chopped lettuce) 2 times weekly with Nutridrench. Every once in a while I won't add it but most of the time I do.
I give the chickens treats about once a week with Nutridrench and without it once a week. Chickens get green beans, lettuce, rice, etc. In the summer I have a great deal with a local produce guy, I give him fresh eggs and he gives me tomatoes, watermelon, cantelope, peaches that he can't sell. You should have seen the great watermelons that he couldn't sell just because they had a crack in them. The chickens were in heaven.