Honestly, I like what you did with the light shining behind her, like an early morning corona about her. It reminds me of an early weekend morning, a coolness in the air, a slight breeze, and the dew is just starting to evaporate as the sun begins its ritualistic climb into the sky. Such a refreshing start to the day, why not start it off with some exercise? Or a game of round up in this case.
I am assuming that her back right leg is elevated a tad? Or is her hoof on the ground? From this angle, it appears she is standing on a small bump in the grass, but I may just be delusional.
Spotless lighting! It was a good choice to put the sun behind her to make the picture have more interesting lighting. I also really like the expression and the style you have, it does feel as if Applejack is challenging the viewer. Awesome job!