The only thing I can add to the cold-room story is the importance of the circumstances under which the animals are butchered/ field dressed.
In Short: Keep the flies off at all costs.
I say this for a few reasons:
1) If you hunt on a freezing cold day in the middle of winter, no problem there are no flies around, but in early/late or out of season hunts this is a big issue.
2) To field dress or not? - There is a fine line between field dressing on a hot day and having a thousand flies zooming all over the animal and keeping it closed to dress at the farm behind the mesh. If you leave it too long, the gas builds up and the animal is about to explode inside and spill guts all over the meat. Make your choice wisely.
3) Field dressed animals left in the veld for any amount of time will be found by flies if they are around. They will go inside and lay tiny little bunches or single long thin white eggs (they hatch into maggots). These can be carefully washed or scraped out. The eggs are not a major problem, because they won't hatch in the cool room. Too cold. Always check the inside cavity for these before you hang your meat.
4) Sitting flies - this is a major problem, because flies sit on shit and anything else that is covered in bacteria. When they walk all over the meat, they inoculate these bacteria onto the meat. This cocktail of bacteria are able to grow under really cold conditions, and after a week, the meat starts to go sticky and smell bad. This smell goes right into the meat, so avoid like the plague. Note, that the meat under the skin of an animal is sterile, until the skin is removed. A cleanly slaughtered animal will just dry out in the cold room and develop a dry biltong like texture the longer you leave it, but with fly contaminated meat, the bacteria produce proteinase enzymes that digest the meat, and make it go sticky and stinky. Nothing freaks me out more than a bunch of skinners working on a hot day in the open with flies sitting all over the freshly skinned meat. Say something - don't let them do it.
5) Skin just before you butcher - if you do decide to hang your meat to get it a bit more tender, it is best to keep the skin on, especially on smaller game that will dry out quickly. (cool rooms tend to have low humidity). The time you loose skinning the animal, you will make up when you work the animal, as you don't have to cut out the dry outer layer. If there has been some fly contamination on the inside, it only affects the meat around the ribs, so its easy to cut it out or chuck it as it is not much there any way. Skin on prevents the above scenario.
6) Shoot it in the head - Not always an option, but if you hang a heart lung shot animal with the skin on. All the blood goo is trapped under the skin to fester. It sounds horrific, but is not that bad. An abattoir is by law obliged to cut this out from the carcass as it can potentially be a health hazard, but in reality, blood contains natural anti-bacterial compounds that confer some level of protection. Further, the blood clots and generally stops the spread of bacteria. I have been cautious about hanging shoulder shot animals (skin on) for too long because of the risk, but you can normally get away with a 7-10 days in this condition at the right temperature. Head shot animals in the jacket can age longer than 7-10 days without the risk of drying or rotting and should be hung at the back of the cold room if you have a lot of meat to work.
Happy chilling 8)