I have a bunch of ducklings and I've been feeding them unmedicated chick starter. I had planned to order brewers yeast to supplement their niacin, but I never did and now the ducklings are already a week old. I don't know if I'm already seeing problems, but I have noticed that some seem to have weaker legs. I'm ordering some brewers yeast tonight, but it probably won't arrive for a while. I read online that greens such as lettuce and peas contain niacin. Would it be safe to feed these to my ducklings? Would it be enough to cover the extra niacin, or would I still need to purchase the supplement? Also, I read that ducklings need grit like chickens in order to eat these greens. I don't have any grit as this time, so is there anything else that I could use? like sand? Thanks!