Flock starter can have the right amount of niacin for most water fowl but even then there can still be one or more that can have a niacin deficiency and not being able to get the proper feed exasperated something that may have already been going on and just wasn’t as noticeable you have to admit vague signs could have been missed with so many in there. So I’d say if this is what it is you should know with in a week.
