Baby chicks missing back feathers

[Magnoliasbirds]

I have 10 5 week old chicks. They have a heat lamp and an area to get out of the heat. They have plenty of water and food, but they have bare areas on their backs along their spines. They have a huge area to play in should i change anything?

 

[MrsEskew]

What is the breed? Is it possible for you to post a picture?

 

[Stephine]

Might need more protein?

 

[Ol Grey Mare]

Did the chicks have feathers on that area (not down, but actual feathers) that have disappeared or are the bare areas where the down has shed before feathering took place?