Clean their butts with warm water, make sure they don't get chilled by drying their butt with a paper towel. Then put enough molasses in their drinking water to make it look like iced tea. They should not plug up again.
Personally, I would only do this for chicks I bought.
I usually hatch my own chicks. Any that get a pasty butt get culled.......
Pasty butt stems from a few things....dehydration in the number one thing along with stress. Shipping to feed stores and even bringing them home is enough to cause pasty butt. So can high heat in the brooder. ALWAYS dip beaks in the water first after bringing them home and don't put any feed out for an hour or so til you know they are all hydrated.
Did you read my PM? In May my feed store is going to carrying many breeds of chicks again and I going to bring handfuls of them home! I may get the cold shoulder for a while around here, but I need babies!!!! I think I burned the hubby out on the thousands of quail I hatched over the years, the constant sounds of egg turners, red lamps burning continuously, the peeping and the 2 inches of dander all over the house. LOL But dang it, need babies! I thought about hiding an incubator in the closet or under the bed, LOL, but I think I can get away with babies a bit easier this time. Incubator later after the shock of more babies.
I want some Barred Rocks and some Silver Laced Wyandottes. But the Wyandottes come in later in the month. I am hoping she is going to carry some rare or heritage breeds too. I will have to find out.
I have heard the Barred Rock hens can be pretty docile. I really like the looks of them. Yes, love the Wyandottes. I am hoping she will carry the different Laced colors too. This is a mom and pop feed store and she will order breeds that you want. I need to talk more to her this week.