Sheep graze on the mountain, rabbits graze, and horses scramble to guess the zodiac.

Rabbits and sheep foraging for grass are horses in the zodiac, because there are cows, rabbits, sheep, horses and pigs in the zodiac, and rabbits and sheep appear in the riddle, so they can't be rabbits and sheep.

Rabbits and sheep are foraging for green grass together. According to the multi-input method, it is a horse.