One of the most important — and most difficult — lessons that we must learn as children is sharing things we like with others. It looks like this bay horse learned that lesson well, though, since he's generous to share some of his hay with his neighboring horse.
This video captures the adorable — and very deliberate — act in which the bay horse holds a mouthful of hay up to the grate between his stall and his neighbor's. The gray horse in the next stall over seems quite happy with this arrangement, munching away thanks to the help of his friend.
The behavior captured in this video is even more notable because many horses are territorial about their food. According to horse trainer Linda Parelli, horses may react according to emotional and dominance-based behaviors when it's feeding time. In a herd, a horse that is dominant over all the other members gets to eat first. Horses learn to fight for and defend their rights to eat, which can lead to behaviors like squealing, kicking, charging and overall anxiety.
Even though domesticated horses rarely live in herd settings, this behavior often transfers to horses when they live in stalls. Food dominance can be aggravated by the regular feeding schedules that people tend to stick to in managing their horses.
However, horses can also create strong bonds with one another, and that's what seems to have happened in this video. Among herd members, certain horses sometimes get along together well. This also frequently occurs in domestication; horses develop "buddies" and can get very attached.
Even though many horses would fight to keep their food to themselves, this bay seems more than happy to share with his friend. Of course, if the gray horse's food is being restricted because he needs to lose weight, then the stall wall may need some modifications for that diet to be effective!