Cornish X With Very Few Feathers

I have 50 Jumbo Cornish X that are 4 1/2 weeks old. I got them from Murry McMurry. They weigh between 2 1/2 to 3 pounds. My question/concern is that they have very few feathers. It's almost as if they grow too fast for the feathers to keep up with their stretching skin. Is this normal? Will they eventually get more feathers? We plan to butcher them in about 4 weeks. They are very lazy birds---they basically eat and poop all day long. There feet and legs are HUGE and very thick, which is understandable as they need to support their large bodies. I just think it is odd that they don't have many feathers and I can see their skin when they stretch out.