Question

give reason why herbivores have long small intenstine

Answer 1

It is because they eat grass that contain a bulk amount of cellulose that takes a lot of time to digest.So in order to digest the properly,they have a long intestinal track .

Answer 2

This is because herbivores are plant eaters and carnivores are animal eaters , if carnivores have long intestine the waste material and excretion takes place for long time which causes infection.
same as herbivores have long small intestine to take better absorption of nutrition and vitamins