I would suggest looking at what your background is when taking the photo. You have a good eye for the most part, but the background should fade away and the focus should be on the object of the photo.
The one of the horse grazing with the barn in the back is an example of angles you want to avoid. At first glance, it appears that the barn is part of the horse's rear. It just ruins the line of his back in what could have been one of your best pics.
As mentioned by another post, don't over process the color pictures. It is harsh on the eye and distracts from the object. You have great potential and I enjoy your photos!!!
Imagining life without a horse is like imagining life without food, water and air.