Duck with neurological issues, doesn't gain weight, need advice

[DuckNoobie]

Hi all,
Rascal is a 4 year old Crested Appleyard drake who had been diagnosed with permanent neurological disorder. The vet was able to conclude this because he doesn't walk much anymore and sometimes has what looks like minor seizure episodes and because all his tests (blood, poop and Xrays) came back clean. We got these results a couple of months back. At that time he still had his summer weight, and my concern now is that he has not gained his winter weight (like my other ducks) even though all he does it sit by the food bowl and eat. My ducks have access to fresh food and water 24/7, they eat Gold'n Harvest by Purina, vitamins, daily veggies, and have daily access to grass and swimming. I'm now switching them to Mazuri food as i was concerned he needed more vitamins that the current food wasn't providing. Another thing that he's recently developed is his feathers became extremely oily and poor quality. See photo attached, you'll see right down the middle of his back the feathers are oily and dirty and his wing feathers are terrible.
My main concern is his his ability to eat all day long and not gain any weight. Has anyone had this issue? (I don't believe he's got metal poisoning that i've read about in other posts). What do i do to put weight on him?
My second concern is the feather quality, which i thought was a vitamin deficiency but all his tests came back normal so I'm at a loss here.
Please share your experiences and suggestions.
Thank you,

 

[DuckNoobie]

@Miss Lydia @casportpony any thoughts?

 

[casportpony]

I was gonna suggest for weight gain that you try a turkey starter or the Mazuri duckling food, but check with your vet first.

 

[DuckNoobie]

I was gonna suggest for weight gain that you try a turkey starter or the Mazuri duckling food, but check with your vet first.

first need to figure out how to feed them the Mazuri, my ducks are not interested. Im assuming it's because of the kibble size. They're used to crumble. Tried crushing up Mazuri with a hammer, no dice. that kibble is strong. lol

 

[DuckNoobie]

I was gonna suggest for weight gain that you try a turkey starter or the Mazuri duckling food, but check with your vet first.

Is your suggestion because of the higher % of protein? Or is there something else that helps gain and retain weight?
My other ducks are nice and plump

 

[casportpony]

Is your suggestion because of the higher % of protein? Or is there something else that helps gain and retain weight?
My other ducks are nice and plump

Yes, higher protein, and it has more of the vitamins, amino acids, and minerals that chicken feed has. This is something I would feed to just the one duck though, not the others.