Any sort of flesh (meat-protein) will serve.
I harvest broths from chicken, pork, beef, Cod, trout, salmon, moose, rabbit, and whatever else is big enough to attack with a carving knife.
When I have bottled/preserved jars of broth and have a 1/2 cup left over, I mix it with two to three times that volume with wholewheat flour, roll it thin onto a baking sheet, and bake as for ginger cookies.
Twenty minutes in I score the thin cake into one-inch squares(1) with a pizza cutter, then continue baking until dry.
Once cooled it splits pretty well into one-inch square biscuits.
Fergus the Sheltie loves them, although I usually have to wait until the car is out of sight when I'm dog-sitting, or Tom tries to yell at me.
Fergus is my BFFFFF!(2)
(1)Symmetric rectangles some 2.54cm on a side
(2)Best Fellow-Foraging Feurry Ferrgus Ferend Ferever