Not part butt but something is going on...

[akqueen01]

1week old chick (thought was a white australorp but maybe a Cornish due to size?) super huge but less slower feather development than all others. Seems bony yet large with tiny wings. Was taking care of hygiene to avoid pasty butt and noticed bottom seems raw? Looks like fur is wet and I'm positive it's not poop. Is this chick ok? Stays at the food and water 90% of the time.

 

[Ridgerunner]

It sounds like it could be a Cornish Cross. It may be growing so fast the feather development can’t keep up. It being that big and staying at the feeder also point to that.

I don’t know if overeating like that can cause that kind of discharge. You might try restricting its feed and see if that helps. Maybe make a large cage or open-topped box out of hardware cloth and set that over the chick for several hours a day so it can’t get to the feed?