Hello all. I have two Pekin ducklings going on two weeks old, one male and one female. The female was showing signs of a niacin deficiency, so I began adding Brewer's Yeast to their feed, but now the male is starting to show signs. The female seems to be better, but not much. Both of the ducklings lie around most of the time and I'm really worried. I've only been giving them Brewer's Yeast for three days now, and I have no idea how fast (or slowly) this works, so I'm hoping someone can help me out. I've read that if it isn't treated early, it can lead to serious issues. I added 1/2 cup of the yeast to 5-6 cups of feed (is this too much? enough?). Should I purchase a poultry multivitamin instead? I'm REALLY worried about my little babies! Any information will be DEEPLY appreciated -- thank you!