Hi Sasa,
This is a beautiful image and personally I don’t think there is too much more you could ask for in this setting. The donkey is posed perfectly (we will thank the donkey for that), the light is great and the old shed is looking wonderfully rustic too.
Now, all that being said, there are two things I would have done to improve this image.
The first would have been to move slightly lower towards the ground as you composed the photo. As it is at the moment the donkey’s head is half against the grass and half against the building… I just wonder if putting the donkey’s entire head against the shed would look better. This might be a personal choice thing.
The second adjustment that I would make is to the dodging and burning of the image. Everything green in the photo is looking gray and flat, to the point that I think you have given too much burning to the green areas, and also at the wrong range. At a guess I would say you have used the Burn tool withte range set to Highlights, which is what the green areas are now looking gray.
Remember that both the dodge and the burn tool can be set to a Highligh, Midtone and Shadow range and you will get different effects depending on the areas you burn with each range.
As an alternate option you might have been better just selecting all the greens and then just toning them down using the curves adjustment.
Whatever you do, the main thing is that a photo looks convincing. I would go back to the original image and have another crack at working the greens.
Cheers,
Anthony