How do ruminants and non-ruminants differ in their ability to digest forage and feeds high in fiber?

Ruminants have a four-chambered stomach which enables to have extra steps to more efficiently digest and utilize the nutrients they get from eating forage and high-fibre feed. Fermentation is one step that allows ruminants to efficiently digest roughage, and a symbiotic relationship with bacteria, protozoa and other microflora that enables the ruminant animal to break down fibrous material in their GI tract. The next step in the ruminal process is that the digest is regurgitated and rechewed as cud, further breaking it down, before it is reswallowed and goes through the fermentation process again. The feed then passes through the omasum where liquid (or water) is absorbed back into the ruminant's system. The "dried" digesta moves into the abomasum (the "true stomach") where it undergoes further digestion by the hydrochloric acid and peptidases that are excreted from the abomasum's epithelium lining.

Non-ruminants, on the other hand, do not have this "luxury." They can only rely on their simple stomach which is responsible for producing really low pH fluid called Hydrochloric acid which helps break down most of their digesta. However, often the acid is not enough to efficiently break down the forage and high-fibre, and thus it simply is passed through the digestive tract as waste.