In sausage the ratio of meat to fat is key. Game sausage especially benefits from added fat. A range of 15-30% fat by weight is common. Unless you have pressing diet issues, I recommend the higher end of the range.

The most common source is pork fat. Beef fat works too but it is less neutral, bringing beef flavor to the game (which may be good). And it and has a higher melting point. My go-to fat is pork “fatback”. Pork shoulder/butt trimmings are great too but usually include a bit of meat, which varies widely based on who did the trimming. Pork butt is 30% fat. Fatback and leaf lard are all fat.

Fresh sausages like this can also use pork belly. Or even bacon if the salt, smoke and “bacony” flavor is a good fit with the recipe.

I could go either way with this recipe: Pro-bacon because I use this for breakfast sausage —- and well, because bacon. Anti-bacon because the point of this recipe is a fennel-forward flavor I want to leave intact. But there is no wrong answer. If you decide to use bacon or belly for your fat source, pick the fattiest you can find instead of the leanest — the opposite of what you do when buying bacon to cook for breakfast.

If picking bacon, adjust the salt down in the recipe to account for the salt in the bacon. And whatever fat source you use, estimate the % of fat/lean when computing how much to use to achieve your desired fat % in the result. Count the venison as 0%.

Recommended ratio of lean/fat based on type of fat:
  –  fatty pork butt, 50/50
  –  fatback or beef suet, 70/30
  –  fatty pork trimmings, 60/40
  –  bacon or pork belly — 60/40 if typical, 55/45 if very lean , 65/35 if very fatty,