! Great to have you here! Do you have more than one? If so I take it the others don't look the one in question? If it's the only one, Cornish X are food gluttons and have that distended rear end - they can look quite unappealing. I wouldn't think pasty butt at this age. Give us a little more info if possible - hope your chicken will be okay!
I have 2, a rooster & a hen, the other doesn't look this way. At first is was squishy & red & as of yesterday hard & red. It doesn't seem to bother him at all. He still eats like a Tank. I noticed he doesn't poop as much as the other one & isn't as feathered. So I thought he was constipated. I'm somewhat treating him for that (karo & water, warm ES baths). I just wasn't sure if its something worse (ascites). We do plan on eating him but are afraid if he has something wrong? Every thread I read is about an eggbound hen & this is a rooster so I thought I'd start my own to hopefully find an answer.