Just to add in here, my shipment of Silkies all have had pasty butt for 6 days. With their black skin it is hard to see so I have to pick each one up and they are so tiny. I have added probiotics, ACV, some scrambled yolk, fine grit, and vaseline on their butts. There was still pasty butt but not as bad. Cleaning them 3 X daily (that is how bad it was) stressed them more but I had no choice. I have never dealt with pasty butt before.
Someone I know told me to get Corid/Amprolium and add !/4 tsp to every 4 OZ and that it wasn't enough to overdose, that their medicated feed had too small of an amount to help with their shipping stress. Well, it worked! A fresh solution in their water every day. She said the breeder told her that diarrhea is no longer the norm for Coccidosis, and the feed doesn't have enough to treat, only a good preventative.