We bought muscovy ducklings for the first time 2 months ago. We have 30 or so ducks of other breeds. Our muscovy ducklings are still inside as they are not fully feathered and we live in WI. We have had a few die off over the last few weeks. About one a week. We have about 3 sick right now. They would get lathargic, stop eating, lose control of neck muscles and either die in a few days or just die without symptoms. We added in brewers yeast, niacin, and a bit of sugar water, which helped the current sick ones eat,stop being lethargic and somewhat act normal but they are still really struggling with regaining muscle control in neck. Any ideas? Muscovies just don't seem to be a hardy breed like our other ducks. We had 2 ducklings that were the same age that were laid on the farm and they are fully feathered and twice as big. Any advice/ideas would be appreciated.