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The Ruminant
Stomach
by Lorrie Blackburn, DVM
Pygmy goats are ruminants
like sheep, cattle, deer, llamas, etc. Their digestive tract
looks and functions quite differently from simple-stomached
animals such as man, swine, dogs, and cats. Knowing some of
these differences can be very important to achieving the best
herd management.
The ruminant animal has a
rumen, reticulum, omasum, and abomasum; the simple-stomached
animal has a stomach. The newborn ruminant functions as a
simple-stomached animal. At birth, the rumen is small and
nonfunctional. When the kid nurses, a band of muscle tissue
(the esophageal groove) closes to form a direct tubular
connection from the esophagus to the abomasum. If you
bottle-feed kids, it is important to hold the kid in a natural
nursing position so the esophageal groove closes properly. If
milk is put into the rumen, either by tube-feeding or improper
bottle-feeding, a considerable time may elapse before the milk
makes it to the abomasum and can be digested for use. Milk may
also curdle in the rumen and cause some colic symptoms.
As the kid matures and
nibbles on his environment, he slowly introduces the
microorganisms (bacteria) necessary for proper rumen function.
Kids raised by their mothers develop rumens more quickly than
bottle babies, presumably due to the mother’s influence on
their eating habits. Very few bottle babies observe their
two-legged mothers eating hay!
Each of the four
“stomachs” has a particular purpose and function. The rumen is
the largest chamber of the ruminant stomach (1-2 gallon
capacity) and has no digestive enzymes. It is a large
fermentation vat populated by microorganisms which change
nondigestible cellulose into proteins which can be used by the
body. Roughage is worked on by the microorganisms, regurgitated
and rechewed (as a cud), then swallowed and the process is
repeated. Eventually the processed food passes on through the
reticulum to the omasum in a condition ready to be digested by
normal body enzymes. Methane is produced continuously as a
by-product of bacterial action, so odiferous belches are a sign
of health rumen. Anything which harms the rumen microorganisms
can effectively halt the digestive process.
The reticulum lies in
front of and below the rumen, near the liver. Its lining is
honeycombed and it serves as a catch chamber for heavy articles
in the feed. In cattle, magnets are often placed in the
reticulum to catch and hold nails, pieces of wire and other
hardware the animal might swallow. Since goats are more
fastidious in their eating habits, magnets are not necessary.
The reticulum from cattle is sold in the market as tripe.
The omasum is divided by
long folds of tissue which help decrease the size of food
particles coming from the rumen and which also help remove
excess fluid.
The abomasum is the true
stomach and is the only compartment which produces digestive
enzymes. It acts on food prepared by the rumen just like the
simple stomach acts on food entering from the mouth. It is the
area of primary digestion of all grain and milk. Grain and milk
do not require the efforts of rumen microorganisms.
While being a ruminant
allows our Pygmies to thrive on a diet of hay, it also leaves
them open to many different diseases which affect the four
chambers of the ruminant stomach.
Excerpts from:
Kinne, Maxine, ed.
Pygmy Goats: Best of Memo
2
(1982-1987)
National Pygmy Goat Association: pp 135
This document is for
informational purposes only and is in no way intended to be a
substitute for medical consultation with a qualified veterinary
professional. The information provided through this document is
not meant to be used in the diagnosis or treatment of a health
problem or disease, nor should it be construed as such.
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