Glorious, what wonderful colour,one of Africa's most amazing antelope. I presume that as you have them standing still that they are used to cars and do not always run away. My only nit is that on my monitor I think that a little more sharpening would help.
They look great in that habitat with the similarity of colors balances so well. I also like the crop and placement of them in the frame. A little more separation between them would have been nice but I know that this is just not always possible.
As mentioned it is a tad soft. Not too to bad however. I also use the 300 2.8 with a 2x. It is a sweet combo. Were you able to use a tripod or did you hand hold this one? But the rich colors, tall grasses, "the two for one special" and the eye on both are looking at you are pluses. Any trip to Africa is special! Thanks for posting.