First off, to kokopuffs, I concur. I have had horse in France and it definitely is a delectable and rich meat. (I do however prefer Bear, even more rich!). Funny how cultural taboos seem to make one food acceptable and the next off limits.
No, I was not aware that the word Pemmican meant beaver in one of the Native American languages. Fascinating!
For Mezzaluna, that quantity of meat per day is astounding, but remember, that these men were carrying loads, dragging boats upcurrent, shivering, working, hunting, portaging, and surviving in an extremely energy consumptive environment. Nine pounds of meat translates to about 10,000 calories per day which, given their degree of physical activity does seem possible. Of course, many were the days when they went hungry, when shots went awry or game failed to appear. You are correct when you stated that game is quite lean, that is why the recipe for Buffalo stew with suet dumplings was one of the explorers most favorite meals. The suet, essentially fat, was quite rare on the grazing animals and was especially prized. (That recipe is also one of my favorites! The suet dumplings are much like a most flavorful gnocchi!).
As for the liver, I do not remember what the price per pound was. If you would like to recreate that recipe, please contact one of the suppliers in the back of the book. They would be most happy to assist you. Or, you can substitute veal liver which is readily available.