My wife has owned horses for nearly 50 years, and couldn’t answer that. Her horses have a somewhat limited menu of grass, hay, Senior Equine, various supplements and the occasional apple and/or carrot.
So if the horses hit Farmer Brown’s carrot patch, would they be able to detect them growing underground and dig them up?
Would they chomp cabbages, lettuce or kale? Would they eat pea pods or the whole vines? What if there’s an orchard as well? I can imagine them crunching apples on the trees, but what about other types of fruit?
Or would they just nibble the weeds between the rows and the grass beneath the trees?
In my experience, horses will eat just about anything that grows out the ground. I’ve seen then eat blackberry vines, cactus, digatalis, roses. I doubt the would pull the carrots up on purpose, but they’d eat the tops.
As to preference… I guess it depends on the horse(?)
My mother’s old house had a small (10 trees) apple orchard in the back. Sometimes the temptation was too much for the neighbor’s horses or cows and one would literally tear down the barbed wire fence to get them. In the fall we would go out and throw the apples that fell on the ground into their pasture and both would be jumping and running around doing happy dances while eating the apples. The neighbor would give us some of the milk from the cows a day later and you could taste apple in it.
From sad experience: A horse will raise hell with a cantaloupe patch. Cows tend to go after green corn. Sheep will eat damn near anything, goats will indeed eat everything and pigs will root up everything. You haven’t experienced trouble until you have had to deal with a fence jumping Jersey heifer.