Hello, and Welcome to BYC! So glad you decided to join!
Could you post a picture of them? A little bit of feather loss around their body when young is normal, they'll often lose a little bit of fluff before growing their teenage feathers, but if it's excessive balding around the eye's/face/body that may indicate there are some poor management practices in play, such as an insufficient deep water source.
What breed are they? Heavyweight breeds should have a feed that contains 70mg of niacin per kilo, any other breeds should have at least 55mg/per kilo. I doubt your feed is satisfying that requirement. For ducklings, Purina Flock Raiser is a great choice and can be fed all the way to death, just provide a calcium source once they are at the point of lay.