Wash them up really well and give their butt fluff a little trim.I noticed it this afternoon on two of my silkies.. We have had a ton of rain the past few days so I'm not sure how long it's been going on. I'm wondering because it's happening to two hens if it's a bacterial infection spread by my rooster.
See if they continue to get dirty.
Vent Gleet is usually a white pasty yeasty smelling discharge on the vent and feathers.
It's usually a fungal/yeast infection.
Does the rooster have any problem with a dirty bum?
Keep your water stations clean, provide fresh feed that is not molded and is in date. Keep treats to a minimum.
Getting a fecal float through your vet will tell you if worming is necessary. Collect a sampling of poop and have it tested.
https://www.tillysnest.com/2012/12/vent-gleet-prevention-and-treatment-html/