Feather loss on chick's butt

[bantamm]

She's perfectly active and otherwise healthy, but her butt looks something awful:

What's going on?

 

[Eggcessive]

She may have had pasty butt, but her vent looks swollen nearly prolapsed from constipation or a birth defect. I would take some vegetable oil or vaseline on a QTip, and insert it into the vent a 1/4 inch, to see if it would stimulate her to poop. You can also use honey or preparation H cream to help shrink the vent area. Let us know if you see any red tissue from inside the vent protruding. Make sure that she is drinking water well, and keep the vent opening clean with soap and water. Measure you brooder temperature with a thermometer, and keep it at 90 for the first week, 85F the second week, and so on. A cooler spot in the brooder to escape to is always needed if they are too hot. Too much heat can add to pasty butt and constipation. Here are a couple of threads about pasty butt and prolapse in chicks:
https://www.backyardchickens.com/t/383876/chick-has-a-protruding-vent-and-pasty-butt-help-pics
https://www.backyardchickens.com/t/1086558/my-chicks-finally-arrived-one-prolapse