Our neighborhood white tail have very little fat and even the leaf fat does not lend itself to a viable end product. I use (unrendered) pastured pig fat in a 60ish/40ish ratio for deer sausage. The"pastured" is an important integer in this equation. Swine that have the benefit of living life on a sunshiny farm soak up copious amount of Vitamin D down into their proper layers of subcutaneous fat stores, whereas factory farmed oinkers do not. And our wild sus scrofa are hairier, leaner and a whole lot fucking meaner. Harvesting their minimal fat is not worth the effort. Back straps, all day. Fat, whole lotta nope.