They may be adequate for the animals that you may be hunting and then again the guide service that you are going to use may not allow them. The best thing to do is to contact the guide service that you plan on using and ask them about it.
I know that here in North America there are guides for moose and bear in Alaska that require a minimum of a .30 caliber and up.
They would be adequate for the smaller of the plains game, but if you're planning on getting into the kudu and eland size animals, you will want to move up to at least a good 30 caliber or better rifle with a good bonded bullet. As critter mentioned, when you pick out a PH to go with, it would be a good idea to get their recommendation to make sure when you get there that they don't say your rifle is too light for the task and make you use an unfamiliar one of theirs,
Let me start by telling you the story of two Johns.
John number one went on a day hike with a couple of friends in the Cascade Mountains about an hour from Seattle. He somehow got separated from his buddies and became lost. John was dressed in casual cloths for a warm weather day hike and had nothing but a lunch with him. He spent three days in those mountains and luckily made it out to tell the story.
John number two, a friend of John number one, was much better prepared when...