The recipe I follow calls for 8 ounces cream per 5lbs of meat. It comes from this book, which i highly recommend.
I got this for Christmas and have made a few of the recipes in it and all have been great. There is one for a white bratwurst that looks similar to the one you posted the other day that is just outstanding.
A couple butchers from Tennessee wrote a great book.
Homemade Sausage: Recipes and Techniques to Grind, Stuff, and Twist Artisanal Sausage at Home https://www.amazon.com/dp/1631590731/ref=cm_sw_r_cp_api_glt_fabc_R3Z75BBZ2D6C3BV3WRN1
If you're looking for a cookbook, this one hasn't let me down yet