Unmedicated anymore isn't so much that the med is harmful but that it isn't necessary. It's a very bad idea for animals or humans to take medications when there are no indications that they're necessary. I agree that chick feed with Brewer's Yeast or niacin alone is better at this stage than pellets.There have been no proven studies that medicated chick feed (amprolium) is dangerous to waterfowl. Pellets for a duckling can be hard to eat. I would do chick starter in crumbles and add Nician tablets (plain not the no flush or time released) to the water since you can't get Brewers or nutritional yeast.