Ruminant digestion - COME BACK TO

What is the rumen?

* Acts as a fermentation vessel
* Lining of the rumen (tripe) provides surface area.
* It acts and digests like a chemostat and makes up 10-20% of a cow's live weight.

How much saliva do cows produce per day, and what are its contents?

Cows produce 150L of saliva per day, and its contents are 85%-93% water.

What are ruminal papillae, and where does absorption occur in the rumen?

Ruminal papillae are finger-like projections in the rumen, with stratified squamous epithelium - keratinized, and absorption occurs here.

What do cows spend their time doing?

Cows spend 8 hours a day grazing and 8 hours a day ruminating.

What happens during ruminating, and how many times is each bolus of food chewed?

* During ruminating, material is drawn back into the esophagus, and muscle contractions return it to the mouth.
* Liquid is rapidly re-swallowed, and coarse material is chewed again before swallowing.
* Each bolus is chewed 40-50 times.

What are reticulo-rumen microorganisms, and what kind of microorganisms are they?

* Reticulo-rumen microorganisms are microorganisms that provide a culture system in the rumen and reticulum.
* They are mostly anaerobic bacteria and fungi and have synbiotic relationships.
* There are over 200 species identified so far, and they include heterotrophic and autotrophic bacteria (including methanogens).

What is the role of methanogens in the reticulo-rumen, and how do different bacterial/fungi break down different food sources?

Methanogens reduce efficiency but impact on the growth of other species in the reticulo-rumen. Different bacterial and fungi break down different food sources. For example, high carbohydrate feed increases the number of lactobascilli, which produce lactic acid and metabolize carbohydrate.

What does fermentation in the rumen produce, and what happens to the volatile fatty acids (VFAs)?

Fermentation in the rumen produces volatile fatty acids (VFAs), which are absorbed, and gas and more microorganisms are produced. More than 30L/hr is produced, and it includes \~40% CO2, \~30-40% CH4, and \~5% H2.

\

What are the structural changes during development in the rumen?

At birth, the abomasum is the largest chamber, and at 18 months, the reticulorumen occupies over 90% of the stomach.

What is the reticulum, and what is its function?

The reticulum is a compartment in the rumen that has keratinized stratified squamous epithelium. Its function is to aid in separation, mixing, and breakdown of particles.

What is the omasum, and what is its function?

The omasum is a compartment in the rumen that regulates the entry of food into the abomasum. It may also return food to the reticulo-rumen, and it absorbs water and VFAs

What is the abomasum, and how does it compare to the human stomach?

* The abomasum is the true stomach in ruminants, and it has broadly the same digestive functions as the human stomach.
* Oespohi

What is cellulose, and how is it digested in the rumen?