One duckling not growing

[BelovedBirds]

This is my second year raising ducklings, and both times I have experienced growth issues with them. Last year I had cayugas and runners; my runners developed shakey legs, which I "cured" by feeding brewers yeast. This year I have khakis and pekins, and one of the pekins is in trouble: it isn't growing, has low energy, has trouble standing/walking, and its toes are beginning to curve inward (like it's becoming pigeon-toed). The other pekin duckling has grown at least for times larger than the one who's having trouble, and they are the same age. The khakis are all developing fine. So, what can I do to help the one pekin who's struggling? I'm feeding Flockraiser (20% protein), chick grit, and I add Avian Super Pack supplement to their water (which has a niacin supplement in it, along with other electrolytes). I can't figure out why the one pekin is struggling to develop, while the others are growing like crazy. Please help...

This comment is old, but for any one reading in future, this sounds like it is a niacin deficiency, common with Pekins, it can be treated with a vitamin B complex- Durvet does a cattle injectable B complex which can be given to the duckling in question as a 1ml dose over a treat, daily.
Other off the shelf treatments (and preventatives) include flush effect niacin tablets diluted 100mg capsule to 1 gallon of water, or 1 tablespoon of nutritious yeast or brewers yeast to one cup of feed.
Both niacin tablets and nutritious yeast are available on Amazon

 

[BelovedBirds]

I have a duckling just like this!

It could be a niacin deficiency, what breed is the duckling? What feed is he on?