I have 130 ducklings, which were doing great, until recently. One by one, they stopped walking, they sat down and couldn't move. From reading other posts, I came to the conclusion that it was a lack of niacin. I was correct. I mixed brewers yeast with their feed, and 4 of the ducks that couldn't walk are walking about happily now. Does anyone know where I can get the feed analyzed to confirm the lack of niacin? I would like really like to keep using the feed mill I have been, but if I can't trust them, I will have to switch feed mills. Thanks!