Simple Explantation of Adult Goat Digestion

and Function of Adult Goat Rumen

The adult  goat rumen is a fermentation vat for the forage, grains and hay  the goat eats. A proper pH balance is necessary for proper digestion and unless somehow the goat's diet is somehow compromised the digestive system should work like a well tuned clock.

The contents of the rumen layer in a manner according to specific gravity and are constantly being fed by saliva, cud chewing  and belching of excess gases.  Naturally , the gas remains in the upper portion of the rumen and next  would be the hay, browse and forage the goat is currently eating and lastly.. on the bottom would be the heavier contents of the feed thew goat ate yesterday and any grains the goat has eaten.

The goat produces approximately 25 to 30 liters of saliva per day.

The solid contents of the rumen move very slowly while the liquid contents move more rapidly through the rumen and further down the digestive tract.  This liquid (saliva) will carry smaller protions of digested matter with it.  As the rumen contracts during normal rumen movements - it pushes smaller, lighter portions of partially digested feedstuffs back into the rumen while allowing the heavier contents to go into the reticulum where it will gather further microbe and flow into the omasum. The actual function of the omasum is not completely understood but  it is thought that is may serve to absorb residual volatile fatty acids and bicarbonate (provided by the saliva). The tendency is for fluid to pass rapidly through the omasal canal, but for particulate matter to be retained between omasal leaves. Periodic contractions of the omasum knocks flakes of material out of the leaves for passage into the abomasum.

The Abomasum (or "true stomach" ) is where the acids are secreted and large amounts of bacteria are produced which are needed to continue proper digestion.

Importance of Cud Chewing 

This is the function of the goat's reticulum regurgitated and rechewed by the goat and then reswallowed. This is important for the full digestive process to occur - allowing the nutrients from the feed to be able to be totally absorbed into the goat's system for  complete utilization of feedstuffs. The reticulum contracts allowing a bolus of ingested feed to return to the mouth, the tongue squeeezes out the liquid in the the back of the throat and the drier feed enters the mouth where more saliva is introduced while chewing this 'cud' before it is reswallowed. This is called rumination and is the most impotant part of the goat's digestive process.  Without being able to ruminate, the feed will not properly digest and the health of the goat becomes lifethreatening. Also during rumination, the goat is releasing gases from the rumen via belching in enormous amounts (Up to 5 liters of Gases Per HOUR for an adult goat) Eructated (belched) gas travels up the goat's  esophagus at 160 to 225 cm per second.

If the goat is unable to express these gases, the expanding rumen rapidly interferes with breathing. goats suffering from bloat or 'ruminal tympany' will die from asphyxiation.

Why is the production of Saliva Important to the goat's digestion? 

The goat's rumen microorganisms have a preferred pH rangeof 6.0 to 6.8. Rumination (chewing the cud—required to digest roughage) increases the amount of saliva, which buffers the rumen fluid and maintains the favorable pH. However, grain (especially finely ground grains) decreases rumination; which means less saliva reaches the rumen,and the pH decreases. Also,in the process of digesting grain, lactic acid is produced, which can further lower the pH. When a goat eats too much grain, the rumen pH can drop below 5.5, killing the normal rumen microorganisms and can result in a very sick animal. (Ruminal acidosis)

• provision of fluid for the fermentation vat
• alkaline buffering - saliva is rich in bicarbonate, which buffers the large quanitity of acid produced in the rumen and is probably critical for maintainance of rumen pH.