I've just seen another post where someone had an impacted crop. I'm sorry for those of you who have had to deal with it. But it brings up a question- is there any way to prevent this?
There are several different types of crop issues ~ impaction, souring, etc. You might try a search of dlhunicorn's personal pages on this topic; she has a great deal of information on it.
The thing is - especially when they free range - you never really know what they are getting into, they could be scarfing down long strands of grass too fast so the other chooks can't get at it.
Or, have too much fun running around in the yard, then decide they need their feed and gobble too much. I'm still trying to figure it out.
There does seem to be a rash of crop issues lately, isn't there?
Lilbizzy - maybe your post will bring in more info!