Lab 3045 The Ruminant Digestive System ACTIVITY OBJECTIVES

Lab 3045
The Ruminant Digestive System
Investigate a ruminant digestive system. Identify organs of the ruminant digestive system
and describe their functions.
This lab is designed to help students understand the ruminant digestive system and to
begin to make comparisons between monogastric and polygastric systems.
Identify the following structures before stating lab: esophagus, abomasum, omasum,
rumen, reticulum, small intestine, large intestine.
A ruminant is an animal with four distinct stomach compartments. Ruminants swallow
food, essentially un-chewed, and regurgitate it. The regurgitated food, called a bolus, is
brought back up from the rumen, chewed completely and re-swallowed. This process
commonly called "chewing their cud" is also called rumination. Ruminant animals
include cattle, sheep, goats, deer and elk.
The reticulum is the first compartment of a ruminant stomach. IT only has 5%of the
storage capacity of the system. The reticulum has a distinct lining that looks like
honeycomb. This compartment is sometime referred to as the hardware stomach as it
holds foreign materials picked up by the animal while grazing. Magnets fed to ruminants
are held in the reticulum along with the collected debris.
The rumen has the largest capacity of any of the stomach compartments (80%). This
compartment serves as a storage area for food. The rumen is host to millions of bacteria
and protozoa. Bacteria action breaks down cellulose in plant material processing it into
usable proteins and B vitamins. Monogastric animals do not have these special bacteria
and protozoa therefore are less efficient in digestion of plant products. A ruminant animal
can consume a lower quantity and quality of dietary products and maintain a healthy
The third compartment called the omasum is a highly muscular section that squeezes
excess water of the food before it enters the abomasum.
The abosmasum contains digestive enzymes that cause chemical changes in the food and
begins the break down of proteins, carbohydrates and fats into simpler substances to pass
into the small intestine.
Ruminant digestive tract(s) Labels
Sharp knife Dissecting Microscope
Pins Reference Materials with pictures
Lay out the digestive system on floor or dissecting tray. Locating and label the
following parts with pins; esophagus, rumen, reticulum, omasum, abomasum,
small intestine, large intestine.
Show the digestion that takes place in each stomach compartment.
Draw the digestive system as you have observed it. Label the organs listed above
in bold face type.
Describe or draw the lining of the reticulum. Why is this called the "hardware
stomach"? Why would a ruminant animal ingests foreign materials?
In which stomach compartment are chemicals used for digestion?
For each compartment, explain it's function:
How does this digestive system compare to that of the pig?