|MadSci Network: Zoology|
Sheep and other ruminants (cud chewers) get much of their caloric intake from the cellulose content of their feed. However, the normal digestive process of mammals in general does not have the ability to digest cellulose, which passes through the digestive system unchanged and unutilized. Ruminants have multi-chambered stomachs and in these there are conditions that favor the growth of microorganisms which have the ability to break down cellulose, utilizing part of it for their own sustensnce, and liberating the rest of the carbohydrate value as smaller molecules (fatty acids for example) which can be utilized by their host. This symbiosis (feeding together) benefits the host and provides a place and a food source for the microorganisms.
Try the links in the MadSci Library for more information on Zoology.