Niacin for adult ducks

I'm pretty new to ducks and have 11 (Welsh Harlequins and Cayugas) which are about 3 months old at this point. I know that ducklings need more niacin than chicks. but I can't find anything conclusive on whether that is the same for adult ducks. When they were young I would add niacin tablets to their water. Now they are mostly free range and hang out in the stream all the time. I tried brewer's yeast with their feed but it seemed so powdery that they didn't actually consume much of it. Anyway, do they even need extra niacin at this age? Maybe they get what they need from foraging...

I've raised dozens of ducks in my life and never gave them niacin but they were free range so they ate what they needed i guess. they love pond weeds!

I believe niacin is mostly for development. If you start hatching, or allowing any of your ducks to hatch eggs, and you notice a problem with ducklings having problems with their legs or wry neck, then it might be good to add niacin into the mother's diet. Otherwise, the adults usually do fine without it...

I've never raised chicks from my birds so guess thats why they never needed it.

You shouldn't need to add niacin once they are adults, but if you do, it won't harm them. The company I buy my chicken feed used to have instructions on adding niacin to their chick starter if using it for ducks, but that this wasn't necessary once they were adults. Here's some info they wrote about it then: https://www.scratchandpeck.com/wp-content/uploads/Starter-suitable-for-Ducklings.pdf And a here's a quote from that PDF.

Scratch & Peck Feeds wrote: Niacin supplementation is important during the starter/grower phases, but not required once they begin laying eggs. 27 mg of niacin is recommended until maturity at which point it lowers to 20 mg. Our feeds contain 22.5 mg of niacin. You can supplement by adding brewer’s yeast to their feed for an excellent source of niacin. One tablespoon of yeast contains approximately 5 mg of niacin.

They now just add in the niacin because chicks (who don't need as much) just flush out the rest.

I hope that helps! And, the Scratch and Peck website also has some nice feeding guidelines and info on fermenting feed, etc, that may or may not be helpful for you: https://www.scratchandpeck.com/learning-center/helpful-guides/

A few of our ducklings had wry neck and we tried the brewers yeats but found vegemite or marmite was easier to spread on a tidbit of lettuce or bread, far easier than the brewers yeast. Vegemite comes in a tube now so it's very convenient. I've never given any added nitrates to adult ducks.

I have a 14 year old duck I took on with severe, long-term leg deformity. I was thinking about ways to get some niacin into her as she doesn't eat a lot. Do you think it would be okay to mix up a small amount of brewers yeast in some water and syringe it straight into her mouth? Or would it be better to crush up a tablet and mix with water and administer in a similar way? Thank you! Faith