100% venison. Im a pretty healthy eater so I don't like to add any fat into mine.

In both our sausage and our "bacon burger" we'll go 50:50 venison to pork. We used both Pork butt and bacon ends in our grindings, usually 30:20 Bacon to Pork butt on the pork side of the equation. When we grind, there's 5 or 6 of us (all my uncles and father) and we all like our stuff to a different taste. I'll throw a bit more garlic and pepper than everyone else, and usually a shot of red pepper to the sausage. I really like the idea of Jalapeno's though, I might have to give that a try this year.

I grind 8lbs Venison and 2 lbs Beef fat together for burger. Beef fat is cheap,if not free.
For meatloaf and meatballs I grind 6 lbs Venison,1 lb Beef Fat and 3lbs pork butt. or 8lbs Venison and a pound each of Beef and Pork Fat.

We go to a local butcher shop and get "bacon ends" just the cut off ends from the bacon they sell there. Generally do about 20% bacon to venison. This gives good flavor as well as adds a little consistency so it sticks together better.
-Jake

We add beef trimmings from the grocery store.

Here in Iowa it is generally cool enough to let the deer hang. The hang time allows us to plan out the butchering. Part of the planning is to call the meat department at the store as it takes a good day for them to accumulate the trimmings. They do do a coarse grinding of the trimmings too.

One advantage of beef trimming is that it is something that they normally discard so the price is usually a dollar a pound or less. Pork trimmings are not discarded by meat departments because it is used in breakfast sausage. The pork is priced the same as the finished sausage. 75 cents for beef or $2.50 for pork. You decide.

We grind the venison, mix it with fifteen to twenty percent ground beef trimmings (on a big table), and then run the mixed meat through the grinder again.

We will grind up 50/50 pork and venison. It turns out pretty good. We ususally will try to find pork roast on sale to grind with.

For every 10 pounds of deer I put in 1 1/2 lbs of hard smoked whole bacon plus a deer jerky seasoning mix. I only use deer for chili and pasta dishes. I usually double course grind it.

Add beef suet

I add pork trim to my burger, at about 25%. Double grind course also.