Stud rolling on the ground.
After lying down on the ground, horses like to roll on their back before getting back on their feet.
This horse was part of a herd of wild horses that were roaming near a mountain pass in Italy. For more info on feral horses, go to en.wikipedia.org/wiki/Feral_horse.
Most of them were Pinto coloured, i.e. with white and brown or black patches, which is a rare coat. For more info about Pinto horses, go to en.wikipedia.org/wiki/Pinto_horse