Weird white feathers on chickens

[Chuckenman]

Basically my chickens have these weird white feathers on them, they werent there before or maybe were less notceable but there are a lot now. Is this natural or is this a disease? Was searching around on the internet and found out it could be vitiligo. If it is vitiligo what caused it? and is there a way to cure it? Does it have other symptoms?
Pictures
Before

Now

 

[Perris]

they are young birds yes? Looks like adult plumage is coming in.

 

[Chuckenman]

they are young birds yes? Looks like adult plumage is coming in.

Yeah theyre about 4 months

 

[HappyClucker7]

What breed are they?

 

[Chuckenman]

What breed are they?

They're all pretty much a mix of breeds. The one i sent the photo of though is a gamefowl or so i believe

 

[HappyClucker7]

They're all pretty much a mix of breeds. The one i sent the photo of though is a gamefowl or so i believe

Probably just the adult feathers coming in then.