Slow feathering?

[User690263]

I have a week old paint Sussex, and she(?) basically has the feather growth of a day old chick. The chick I'm referencing is the light yellow one, the dark colored chick is my Speckledy (RIR x Maran) chick of the same age for comparison. What do you think could be causing this? Do you think it's genetic?
Thanks!

 

[User690263]

If it helps I'm feeding them Purina medicated start and grow. I know that I should switch them to unmedicated, but I'm finishing the bag of medicated first.

 

[Altairsky]

Probably genetic.