I am feeding mostly muskrat, with an occasional meal of beef, and a few junks of chicken fat or skin added every now and then. I feed the whole muskrat, meat, bone, liver, kidneys, etc. minus the pelt, stomach, and intestines. Muskrat meat is a rich red meat that has a good amount of fat, and lots of protein. Muskrats are a clean and mostly vegetarian, much more like a rabbit than an actual rat. I freeze it for over a month to kill of any potential parasites, just to be safe. This is the nutritional content of raw muskrat meat...
http://www.nutritionvalue.org/Game_meat,_raw,_muskrat_nutritio