Third Entry

Today I will be talking about the cow's digestive system.

The cow's digestion body parts are slightly different from that of a human.

Firstly I would like to share a astonishing fact that I found on the internet:

"The dairy cow is a magnificent producer of food. In approximately 10 months, a good cow can produce 496 pounds of protein, 784 pounds of energy in the form of the sugar lactose, 560 pounds of fat, and 112 pounds of minerals all in 16,000 pounds of milk. This is enough protein to supply the needs of a man for nearly 10 years, enough energy for 5 years, and enough calcium for 30 years."

Amazing? I found it amazing though.

Reticulum

This fermentation vat is composed of two areas called the reticulum and the rumen. The reticulum has a distinctive "honeycomb" appearance. It aids to help bring boluses of food back up to the mouth for rechewing. It also serves as a receptacle for heavy foreign objects that she eats.

Rumen

The rumen is, by far, the largest compartment. Its purpose is to store large quantities of feed, keep the feed mixing by strong contractions, and to provide a suitable environment for the bacteria and protozoa to live. This environment is kept agreeable to the microorganisms by maintaining a relatively constant temperature and pH and by removing many of their waste products.

Most of the waste products are volatile fatty acids. These volatile fatty acids are the primary sources of energy for the cow. They are absorbed by thousands of "finger-like" projections lining the bottom and sides of the rumen wall. These can be 1/2 inch long and they increase the surface area of the rumen so as to increase her ability to absorb volatile fatty acids.

Omasun

Once the feed has been reduced in size by chewing and digestion by the bacteria and protozoa, it can pass into a third compartment called the omasum. It looks like an open book with three sides bound. The tissues within are likened to the pages of a book and are called leaves. Up to 100 leaves can be found in the omasum. These leaves have small papillae on them which absorb a large portion of the volatile fatty acids that were not absorbed through the rumen wall. Water and electrolytes such as potassium and sodium are likely absorbed here as well thus drying out the foodstuffs before they enter the next compartment.

Abomasun

This fourth and last compartment which make up the cow's stomach is the abomasum or "true" stomach as it is called because it functions in a very similar way to the stomach of a man or pig. As in the omasum, the abomasum contains many folds to increase its surface area. The pH of the digesta coming into the abomasum is around 6.0 but is quickly lowered to about 2.5 by the acid. This creates a proper environment for the enzymes to function. The chief digestive function of the abomasum is the partial breakdown of proteins.

Small and Large Intestine

The small and large intestine of a cow is similar to a human's. The intestine also has villi to help absorb the digested food into the bloodstream.

Links/Resources:

http://wiki.answers.com/Q/How_does_a_cows_digestive_system_work
http://msetdata.rst2.edu/portfolios/b/brewster_r/rumen/images/zepictures/cow4%20copy.jpg
http://edis.ifas.ufl.edu/DS061
http://www.ca.uky.edu/Agripedia/GLOSSARY/digecow.htm