Just a few questions
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Are they friendly at all? If they are shy/skittish you might want to keep them in the coop longer until they are used to you and you make friends. Otherwise if you let them out you might not see them again, or it could be extremely difficult to get them back into a shelter for the night.
Bread is very bad for ducks, so it should not be given as a treat. Try things like corn, peas, kale, mealworms, or lettuce instead. :)
I'm with Orca5094 on this one. Are they fully feathered yet? And what kind of temps are you experiencing? Suggest giving it time and spending more time for them to get to know you and you them. Start finding yummy snacks now. Ours are so darn picky... And use your leftovers to your advantage. If there are pieces you've trimmed off of vegetables or even some that are left over, throw those in and let them attempt to eat. On that, you'll need to cut it up small enough so they can eat it. I think that's the mistake we made last year with some squash and other gourds we put out for them. Smaller pieces would have been easier.
Just my two cents.
Troy & Tina
And one thing I forgot - they can be lightening quick and quite agile. The spouse and I spent over two hours chasing down an injured duck on our property that jumped out of a plastic tote we were keeping him in. It's a long story, humorous now looking back, but taught us valuable lessons that will stick forever!!! So unless you have a solid enclosure that you guarantee they can't get out of, still be careful because they see the openings you and I miss.
Hope this helps,
Troy & Tina