Myself, I get day old Chicks and I don't offer treats till they are 10 weeks old.I’m just wondering how old chicks and ducklings need to be before you can start feeding cracked corn( as a treat)
Of course any treats they find themselves when I put them outside at 5 weeks. Like bugs, worms and vegetation is OK.
The only treats I give daily is Scratch Grains that I add a Cardinal seed mix to. I think its healthier than just cracked corn.

They get their veggies, bugs and worms when I let them out an hour before sunset daily, weather permitting.
