I came home today, and went about doing my daily animal chores. I filled up the water fount in the gosling and duckling brooder and then left to feed the others. They were perfectly fine - making baby goose and duck sounds and drinking water and eating. I went back into the barn and both of the goslings and one duckling are laying on their backs, flopping around like fish! They died within minutes. I looked in their mouths and no food that could cause them to choke. What in the world could have caused this? This was so strange. Absolutely no signs of sickness or disease. They were 10 days old. The remaining two ducklings are just fine. Any ideas?