Is that bag you posted, the brand I should be looking at next week when I go to TSCMany of the turkey starters will have bacitracin, which ducks *can* have, it's actually what I feed my peachicks, ducklings, and poults.
More links:
http://metzerfarms.blogspot.com/2011/11/can-medicated-feed-be-used-for.html
http://metzerfarms.blogspot.com/2011/03/are-my-ducklings-leg-problems-due-to.html
More on medicated feed: