The length for cooking a venison roast depends on the weight of the roast itself, but on average, it should roast for 45 to 50 minutes per pound. For example, a venison roast that weighs 4 pounds will take approximately 3 hours to cook at 325 degrees Fahrenheit.
One way to prepare a venison roast is to cut several slits into the top and sides of the roast, and then place a peeled garlic clove in each one of the slits. Rub the entire roast with a variety of spices, such as rosemary, garlic powder, onion powder or thyme. Roast it with vegetables (such as onions and carrots) in a pan until it reaches an internal temperature of 130-140 degrees F for medium-rare.