This too shall pass.
I thought I had this problem figured out -- haven't had pasted butts in a long time, maybe 12 or 15 years. That's about when I started raising chicks mostly on game bird starter instead of chick starter, so I figured there must be a connection. Well, maybe. But I've got a batch of bantam chicks, and at least half of them have pasted butts. Sigh. It's frustrating. Also interesting. The chicks are about half Rhode Island Reds (bantam) and Buff Orpingtons (bantam). The BO's are pasted up a lot worse than the RIR's, although some of the RIR's are pasted up a little bit. So there may be a genetic factor, in addition to feed. Anyone have thoughts on causes and solutions? I'd rather prevent this than deal with the caked-on poop, if at all possible.