I am assuming you are making suasage? The processor we use puts about 20-25% when he makes sausage. When he makes venison burger he uses beef fat at the rate of 5-10%.
20% for sausage 10% for burger , measure by total weight of the ground , If you want leaner burgers you can always skip the fat and simply add a small hand full of instant potatoes and mix well this will hold your burger together !!
i like the 25-06 avatar. reminds me of the two blonds walking down the street and discovered a compact . one picked it up and opened it to see the mirror. she said "she looks familar" the other grabs it out of her hand and looks. you fool its me!