You might also want to get some vitamin b complex from the feed store because ducks need a lot of niacin and twice as much thiamine as chickens.I have starting today. I been trying to get her to eat duck food for 2 weeks now and she won't eat it. I will keep trying....I feel guilty for giving her veggies.
http://www.poultrydvm.com/condition/thiamin-deficiency
Here is a video of a hawk with a thiamine deficiency. The left is before treatment, the right is after treatment.
This is what I suggest you get:

or this
