Why the corn syrup? seems it would cause a duckling to have Hypoglycemia especially if not eating yet? Just a question only not saying it isn't the way to go, I've always just used Poultry Nutri Drench in the water on newly hatched ducklings and chicks.
It was posted on here for mammals, but after doing some reading it's ok to use for ducks it just needs to be mixed with water. I personally use polyvisol without iron, omg this stuff is like heaven for me. I have used poultry drench and it is just as good..