Their legs will look crusty.
Though since they are so young, this may not be the case at all.
I do think it's either parasitic, or something to do with eating spoiled feed or something they got into.
Do they go through your compost pile?
		
		
	 
Just checked out the legs, the legs look normal to me.  
The large fowl ones go into the compst pile every now and again.  I don't let them out to wander the yard very often lately since it is cold and I"m not out there.  I usually only let them out if we can watch them and make sure they don't go to the neighbors 

  But, they did go out there last week and they did go into the compost pile.  But the silkies did not.  I don't normally allow them to wander because I'm paranoid about hawks 
 
  
I called the feed company about the weird looking food.  But, even if it was that, that wouldn't explain the silkies either bc they have different food.  the feed company is having me drop off a sample to one of their retailers, who will get it back to them in a couple of days.  They're also providing me a free bag of food for doing it LOL.  nice!  
 
I'm really leaning towards parasites at this point.  I have to drop that food off at the feed store anyway today and I don't like driving out that way more than once, so I'd like to pick up some wormer while I'm there.  Which is best?  they don't have any of the valbazen, I called.  they said they have the ivermectin.  I don't know if they have safeguard or what.  the one time I got some from them, they handed me a bag of pellets and said to give them 5 pellets each or somethng like that.