duckling not eating

So I have about 15 new ducklings over the span of a week this duckling came out fine and was walking drinking water. I have noticed the 3 babies born at the same time are about 2x his size and growing eating and pigging out on food. This one is rather slow and always sleeping, standing or...

I am new to owning ducklings and they were eating there food but now they only want treats and they won’t eat their food I give the food and water 24/7 and they will only drink water but not eat there duckling starter need help I have two rouens and two cayugas and they are about two weeks of...