There are different types of fat and they will all be used but for a different purpose. There are hard, medium and soft fats and they have a different texture and different melting point. There is a: bacon fat, back fat, dewlap fat, jowl fat, kidney and casings fat and so on. Some head cheese and emulsified sausage recipes call for jowl fat that may be hard to obtain. From the photos it looks like bacon may be a good replacement but it is not. Bacon is a soft belly fat and dewlap/jowl is a hard fat. Fatter cuts from a pork butt are a much better choice that have hard fat and meat (class IIB).
Asian Meat magazine asks Johan how to make sausage ‘healthier’
Responding better to demand for healthy food Sausage may be popular in much of Asia, but the snack has a lot of catching up to