Rabbits feed on plants thus classified as
herbivorous. They have a unique digestive
system that allows them to break down
indigestible plant material to manageable ones
through hind gut fermentation.
Rabbits enjoy chewing hard plant feeds to
strengthen and sharpen their teeth, but like other
animals, they are susceptible to malnutrition.
However, to be able to provide a rabbit with a
more nutritious diet, you must understand how a
rabbit digestive system works.
Functions Of The Rabbit Digestive System
The primary role of the rabbit digestive system is
to digest food and absorb nutrients. Digestion in
rabbits allows them to breakdown food into small
manageable units that are absorbable through
the digestive tract wall. This supplies the
animals with nutrients for daily use, growth and
development and use during pregnancy and
lactation.
Rabbit digestive system also provides protection
from bacteria or toxins in food and during waste
removal. The environment in the rabbit’s
stomach kills most of these bacteria, while
digestive enzymes and acids aid in destroying
toxins. The immune system of the rabbit works
with the digestive system to prevent infections.
Parts Of The Rabbit Digestive System
Rabbit’s Mouth
Like most animals, digestion in rabbits begins in
the mouth. The rabbit uses its lips (prehensile)
to grab the plant and pass it to the teeth for
cutting and grinding. It has 16 baby (deciduous)
and 28 permanent teeth. Since plant material is
coarse and abrasive, the teeth grow continuously
for efficient cutting and grinding.
The permanent teeth consist of 2 lower and 4
upper incisors, and 22 total premolars and
molars. When looking at the rabbits’ teeth, only 2
upper incisors are visible because the other 2
are smaller and placed behind the visible pair
(peg teeth). The incisors tear and grab plants.
The rabbit has 2 lower and 3 upper premolars
and 3 lower and upper molars, occasionally
called the check teeth. They help in grinding the
food to smaller parts to aid in swallowing.
Rabbits also have saliva to moisten and lubricate
food to allow easy movement through the
gastrointestinal tract.
If a rabbit feeds on a diet low in plant material
or fiber, the teeth will continue to grow without
wearing out. It may also develop malocclusion
(overgrown and misaligned teeth). It is a serious
dental problem that requires treatment.
Rabbit’s Esophagus and Stomach
Food passes through the esophagus and into the
stomach. Rabbits have larger stomach for their
size to allow them to hold large amounts of
foods because they are crepuscular – actively
eat during dawn and dusk.
In the stomach, acids and enzymes break it into
smaller particles (hydrolytic and enzymatic
digestion). The main secretions of the rabbit
stomach are mucus, pepsin, and hydrochloric
acid. Mucus offers lining to protect the stomach
from acids and enzymes as well as moisturizing
the food.
Pepsin is an enzyme that breaks down proteins.
Hydrochloric acid decreases stomach pH levels
and kills any bacteria in the food. Stomach
muscles help with mixing the food with stomach
secretions into a mixture called digesta or
chime.
Rabbit’s Small Intestine
Chyme or digesta passes from the stomach into
the small intestine, a flow regulated by pyloric
sphincter. Most of the digestion and nutrient
absorptions occur in the small intestine. The
small intestine consist of three sections namely
– the duodenum, jejunum, and ileum.
Duodenum is the first section of the stomach,
where most of digestion occurs. Secretions from
the pancreas increase pH levels to more neutral
levels. This is because stomach acids decrease
pH levels in food. Duodenum secrete enzymes
like proteolytic, amylolytic (starch digesting) and
lipolytic (fat digesting) to break down the food.
Jejunum is mid-section of the small intestine
which absorbs glucose, amino and fatty acids.
The ileum is the last section of the small
intestine, where the remaining nutrients and B
vitamins are absorbed.
Rabbit’s Large Intestine and Cecum
These are the final sections of the rabbit
digestive system. Cecum is a pouch or sac that
makes a junction between the small and large
intestine. The large intestine, also colon goes
down from the small intestine to the anus.
Food and fiber passes from the small intestine to
the large intestine where it is sorted into 2 parts.
One part is further broken and used and the
other indigested part is passed directly into the
large intestine. Water is reabsorbed here and the
material is passed as round droppings.
Digestible material (soluble fiber and proteins)
are further broken down and moved into the
cecum. Bacteria and other microorganisms
reside in the cecum, which holds 10 times the
capacity of the stomach.
These bacteria help in fermenting or digesting
the material passed into the cecum, and uses it
to produce their own cells, vitamins and proteins.
Bacteria are important as they help in turning
indigestible fiber into digestible nutrients, which
are absorbed directly across the cecum wall
while others are excreted.
After 8 hours, material from cecum is formed
into small moist pellets called cecotrope, which
are nutritious. Once passed out, the rabbit will
immediately eat them. Cecotrope also go
through the entire digestive system to allow the
rabbit get additional nutrients from plant material
through a process called cecotrophy.
Conclusion: A rabbit’s diet should contain high
fiber in order to provide proper dental health,
ensure movement through the gastrointestinal
tract, and to help with fermentation in the
cecum. Fiber should come from plant to allow
adequate use of nutrients since the rate at which
fiber is passed is relatively high. A high fiber
helps in maintaining a healthy digestive system.