We have 10 Welsh Harlequins and probably 25+ muscovies. We raise many ducklings in spring. Currently we're feeding a custom grain mix from our local mill. Soybean meal, corn, oats, vitamin/mineral mix, and molasses (to keep dust down). I asked for a thiamine supplement many moons ago, so they also added Biotin... I'm embarrassed to say that I never looked into it to see WHAT biotin actually WAS. Turns out, it's not thiamine! LOL. The birds also free range and have free choice access to alfalfa hay (which they pick at), ACRES to roam in, and free choice oyster shell. Anywho, I'm wondering what feed mix additives would supplement my ducks with thiamine/niacin, without breaking the bank - and be mixed by the TON. I'm not gonna go out there and measure/top dress on a daily basis, I want it mixed in.