I really hope someone could help me with this, almost everyone who uses incubator to hatch mandarin eggs failed to raise the duckling older than 3 weeks old, the ducklings will be just fine and usually at the third week they will die without any obvious reason, the chick will be fine and two minutes later he will be dead. Someone told me they might need some kind of vaccine, but asked few breeders in the US and they said they don't use any. So why are they dying? This year i got my first ever mandarin egg, and i don't want the ducklings to die too, so any suggestions? I will let the hen hatch them.