For What It's Worth: Flock Raiser. I have a mixed flock of chickens, ducks, and geese. My goose just started laying, and I only have one Pekin drake (need some ducks), but also have chickens, both roos and hens. I went with Flock Raiser due to the waterfowl, but have found all of my birds are very healthy on it. My hens have laid eggs all winter long (less than usual, but still consistent), and have shown nice body size and feather health. I still think extra niacin might be beneficial for young waterfowl especially, because I did notice a couple of times that my drake was ouchy on his leg (no evidence of bumblefoot, so feel he just was growing so fast he probably needed even more niacin), but my geese have been very good throughout. I feed BSF larvae and scratch for pleasure, treats, and calcium benefits, as well as free choice oyster shells, grit, and I feed their eggshells back to them (baked and crushed; they eat them like candy). They also semi-free range (limited area within electric poultry netting) during the day, and live in an open air coop/pen. I've hesitated to even try the All flock and other choices due to the lower protein and the added calcium that the drake, gander, and roos would be exposed to. I've had them on flock raiser since the first set of chicks were about 2-3 weeks old (they started on chick feed, but converted to Flock Raiser as soon as I acquired my waterfowl and a second set of chicks which have eaten Flock Raiser their entire lives). I see no difference in health between the second set of chicks and the first, including the Cornish Cross roo and hen I have who have been free ranged and fed Flock Raiser the entire time. I figure next year I will see if this was detrimental to the Cornish crosses, but at this time they are all healthy and tolerated last summer's heat and rain... without any evidence of more stress than my other flock members. I may find they drop dead of little heart attacks in the summer, but I won't know until or unless that happens. Additionally I know I am raising them on farmland that has had coccidia present in the past, but none of my birds have shown any illness despite never receiving vaccines or medicated feed.
The Niacin is, indeed, CRITICAL for waterfowl, particularly at the beginning of their lives. I wish nutrition labels would disclose levels - I have ducks as well.