Dirty bottoms

[Bonnieboo]

Two out of my four hens continue to develop dirty bottoms.
I have wormed all of them and cleaned the two with grubby backsides, but it seems to keep happening.
These two are eating, drinking and laying as normal, they just don't seem to be keeping themselves clean for some reason. Their poos are normal and they seem perfectly happy.
What could be wrong?

 

[aart]

If they have particularly fluffy butt feathers, it might be best to trim the feathers collecting the poops off.
Instead of washing the poop off, cut the feathers about 1/4" from the skin.
I use nose hair scissors for this task because they are small, very sharp, and have nicely rounded ends. (of course then those scissors are dedicated to chicken chores).

 

[Bonnieboo]

Thanks for your reply Chicken Juggler. Your idea makes sense however, my other hens have fluffy butts but don't seem to have the same problem. Also, it's just started happening over the last couple of months, they were always clean before.

 

[StinkyAcres]

Did they just start laying when the poopy bottoms started?

 

[StinkyAcres]

And have you been giving any new treats or do they have access to new grass?

 

[Bonnieboo]

They've been laying for at least 3 years. Nothing new in their diet either. Also, the other two hens don't get dirty bottoms. Those two are a bit younger though.