[Arnt]

I wouldn't know about Africa. But I know a thing or two about keeping animals at the edge of the arctic.

If you butcher when the animals are old, you have quite a bit lower risk of losing the meat due to disease, because old animals fall ill more than young ones.

If you butcher, you have some control over the timing, which helps with using the food. You don't have perfect control, but more than random, and you reduce the risk of having to throw anything away.

So if you use the animals both live and dead, it makes sense to optimise for keeping them alive long and die while still healthy (healthy enough to eat/use, if you want to be cynic).