I can't answer that but can share what I see. We use chuck roast, add the recipe ingredients and let it go. Once the butter melts and the juices in the meat seep the roasts are submerged in it's own juice and the butter. Venison is more lean so I suspect fewer juices from the roast. If it where me I would keep an eye on it for the first hour or two and if it looks like it may not be cooking in enough juice, add beef stock or even water. Hopefully someone else that has tried deer chimes in and gives a better answer.