There has a lot of other stuff in it that I’d be concerned it might not all be good for Ducks . What you need is the niacinamide. In your tablets , The Niacinamide is 200 mg for a 2 tablet dose. Are you giving one full tablet a day? I use Durvet liquid bcomplex , I get it from the feed store , or from Amazon. It has 100 mg niacinamide per one ML of liquid that I give orally to my duck with a syringe once a day if they are having leg or foot problems that might be helped by niacin.Here is the B complex I am using.
But if what you have is or you can get, perhaps you can look up all the other extra ingredients and see if they are safe for Ducks.
https://www.backyardchickens.com/ar...dications-to-all-poultry-and-waterfowl.73335/
