How is the length of the intestine related to the food habit of the animal?

In herbivores the small intestine is longer where as in carnivores it is comparatively smaller. The difference in length of small intestine is because of the food habit of these animals. Herbivores are grass or plant eating animals. Plant products have cellulose, which takes longer time to digest. Because of the relative difficulty with which various kinds of plant foods are broken down (due to large amounts of indigestible fibers), herbivores have significantly longer and in some cases, far more elaborate guts than carnivores. The long intestine allows adequate time and space for absorption of the nutrients. Carnivores are meat-eating animals. Since  meat is relatively easily digested, these animals have shorter small intestine.