Question

why herbivorous need large small intestine

Answer 1

HEY DEAR....
HERE'S YOUR ANSWER⬇
Herbivores animals need larger small intestine for the digestion of cellulose. Cellulose is found in green plants. Meat is easier to digest. Since plant is all they eat, they need a longer intestine.
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Answer 2

herbivorous animals eat food which contains cellulose in them, and its difficult to absorb cellulose in a smaller small intestine, so they have a larger one