Most poultry will try seeds. What type of millet? Some like red millet some don't like. If you've offered it multiple times and they don't want it they probably won't eat it. It can sometimes help to put it in their food dish so they try stuff.
Chickens, muscovy ducks, turkeys, donkeys , goats, dogs, bunnies, fish, parakeets, a parrot, and a cat.