This is definitely good advice. However, you really don't need to go out and buy new heavier arrows just for African plainsgame. Unless you have an extremely large animal on your list such as an eland, cape buffalo, etc..., an arrow set up that is effective on whitetails will work just fine. Lots of first time African hunters go out and spend alot of money that they really don't need to spend on broadheads, new bows, and arrows. To give you a quick example, my wife has taken at least 2 dozen plainsgame animals in Africa. She shoots a 48lb. bow with a 380 grain total weight arrow. She has gotten many pass-through shots on animals as large a zebra with that set up.
I would recommend you put the biggest emphasis and money spent on a heavy duty, fixed-blade, broadhead. Choose the largest one you can that flies well with your set up. I would also recommend that you study shot placement on African game. There is a great guide for that here on AH.com. If you put the arrow where it needs to be, you should not contact any bone upon entrance. The penetration will be deep and the job will get done. Leave the mechanical broadheads at home. They are very poor performers on African game.