Herbivore and Carnivore digestive systems

A dog is a carnivore with a diet high in easily digested protein so it has a short caecum and large intestine. The caecum is short as very little digestion occurs after the stomach due to the protein rich diet. However, the sheep is a herbivore with a high volume diet of difficult to digest plant material, eg grass containing cellulose, so it has a long large intestine an caecum. Food must stay in the sheep's digestive system for much longer so the micro-organisms in the gut have time to carry out extra cellular digestion of cellulose and allow the maximun nutrients to be absorbed. The caecum contains a large number of different types of bacteria to digest material not broken down in the stomach or small intestine.

The dog has an acidic stomach with a low pH, where enzymes can digest protein that make up a large part of their diet. Whereas the sheep has a four chambered stomach with the first chamber, rumen, having a high pH alkaline environment needed for the microorganisms that do digestion. The sheep has an acidic chamber where proteins in micro-organisms are digested.

The sheep has a much larger large intestine that the dog as plant material is only partially digested so lots of faeces are produced. Dog's food is highly digestible so it has a small large intestine which is mainly involved in the absorption of water. But some bacteria live in the large intestine and caecum,eg to digest some carbohydrates, which increases the efficiency of the dog's digestive system.

Dog                                                      Sheep