Is it normal for young cockerals to be missing feathers on the back?

[tjs22]

My little buff orpington that I raised since it was a chick, feathered out way slower than the others for some unknown reason. The back above the tail being the last place to start sprouting featheres. Before any real feathers started to come in it had shed its fluff and was bald back there for a few weeks.

 

[JDB99]

Update. The fluffier one ended up having a crop issue. I think I may have in under control. 3 days ago it was watery and about the size of my fist after dawn. I began giving some 7 day yeast infection cream and the fluid went away overnight. The next morning it was about the size of a tennis ball and doughy. So I gave her more cream and olive oil then messaged her crop. I've also been wetting starter into a slurry and mixing probiotic pill into it. Just a few minutes ago the crop is smaller than a golf ball after 4 hours of no food, but I could feel it going down as I massaged it. So I think I might be good to go on it. The other one has had no issues other than his feathers. Both are now eating like mad since I've started mixing in the probiotic pills. Any suggestions on helping them to put on more mass other than the starter?

 

[Wyorp Rock]

Chick Starter is usually around 18% protein.
You can use an all flock/flock raiser that is around 20%.

IMO I would not go over 20%, if they were caged and did not have a proper diet, they may be a bit small, but should start filling out nicely with a good poultry feed.

The crop issue may also play a part in not having as much mass as could be expected.
Sometimes a little patience and let them grow naturally would be best.