That is so terrible!  I had the same thing happen one year.  My boys and I left to go get groceries for Thanksgiving, and the birds----about 20 chickens and 2 beautiful ducks---were all out free-ranging.  We came back an hour or so later to find all but 2 of the birds laying all over the yard dead!  The 2 that survived were a one-legged buff orpington hen and a young grey silkie roo who both had the sense to go up on the porch and sit as still as statues----I think that was the only way the hen knew to protect herself, and the roo just followed her.  We found out later that it was a neighbor's dingo that had killed them-----their invisible fence had shorted out.  They wanted to go get me replacement chickens from an Amish farmer they knew!  Hubby said, "You don't understand, these are special breeds that she picked out from someone she knows, and we just want the money to go and pick out our own replacements."  At first, they resisted, but the girl's father must have told them they could get sued over it, and they paid.  Hope you find out what dog did this, and hopefully the owner---if there is one----will reimburse you.  I am so sorry this happened to you, it sounds like you had gone to a LOT of trouble to get just the breeds you wanted.  Wish I could do something to help.