Can a 16~17 week duck recover from niacin deficiency without permanent damage?

[CLUlelSS]

I got these two ducks back in march, and discovered a niacin deficiency in both of them 3 months ago. They are 16-17 weeks at the moment and I gave them a vitamin B-3 supplement 3 months ago (the durvet liquid one at TSC) i have used about half the 250ml bottle and one duck seems to be alright (still a little wide in terms of space between both legs) they cant jump and would occasionally use their wings to get up. The other one can hardly walk and would usually sit on their leg joint most of the time but can walk when running away from someone. I started with 1ml per day over peas/corn and when i ran out of that i tried cabbage (they wont eat it) and I don’t want to feed orally either. Eventually I resorted to dripping about 4ml of it in their feed since I couldn't purchase any grit. I still have half the bottle and was wondering if it would still be possible at this age for them to recover and be able to jump/sit with their feet under their body not next to it. I have OTC niacin tablets at home if adding that will help?

 

[CurlyQuail]

If their bones are pretty set in their growth I would say there’s not much you can do