I haven't rendered deer fat. First there isn't much and second, I always assumed it wouldn't taste that good. I have rendered hog fat, beef fat and buffalo fat. I haven't rendered it myself, but the most magic stuff is rendered bear fat. It's an ingredient in virtually every home remedy from the past that requires oil. It absorbs into the skin better than anything. Next best might be lanolin, but lanolin sort of sits on top of the skin for a while before gradually absorbing.