According to an article written in December's issue of Bowhunter by Master Chef Milos Cihelka, you should age a deer up to 2 weeks.
"To cool a deer in warm weather, you may place bags of ice in the body cavity, but do not let the ice or run-off water contact the meat".
"In warm weather, the carcass will attract a lot of flies. An application of "hot oil" will help. To make hot oil, put two cups of vegetable oil into a saucepan on the stove. Add a handful of crushed red pepper. When it begins to sizzle, remove it from the stove to cool, and then store it in a jar".
"To use the hot oil, make sure the deer cavity is dry; otherwise, wipe it dry with paper towels. Spill a little oil on the palm of your hand and smear it over all exposed flesh, including the nose, mouth, vent, and shot holes. Do NOT coat the pelt. The oil will not affect the taste of the venison".
He further states that "Deer and other game, if frozen fresh, will be tough and strong-tasting. The rigor mortis needs to relax. During aging, the enzymes naturally present in all meat gradually breaks down fibers. As in wine, which is not fit to drink when first made, aging also mellows the flavor of game".
"The optimum temperature for aging is 38-40o F. Higher temperature speeds up aging; lower temperature slows it down. Without refrigeration, deer harvested in early bow season are often difficult to keep safely much longer than 3 weeks. On the other hand, we may have a problem keeping a deer shot in December from freezing".
"I age my deer in the garage. It is important to have some ventilation. Hang the deer head down, placing a stack of newspapers under it to collect drainage. Put a stick in the body cavity to keep it open. Note: Check the cavity every day or two to make sure it remains dry. If any slime develops, wipe it off with a towel soaked in vinegar. It should dry again in one day".
"If the daytime temperature rises to 50o F, or drops at night to 28o F, there is nothing to be concerned about. However, if it gets over 50 or below 28, then we have to make some changes. If you see fly eggs on the carcass (in moist places such as the neck opening), you will have to skin and butcher the deer soon. In freezing weather, I have placed a small electric heater close to the deer and wrapped a tarp around it to make a kind of tent".
"During the firearms season, when there is no more problem with flies, I hang a young deer for 3 to 4 weeks. During the second week, small white specks of mold will appear on the exposed surfaces. This is a natural occurence and nothing to be concerned with, as long as the surface stays dry to the touch".