Transcript DIGESTIVE SYSTEMS OF HORSES AND COMPANION ANIMALS

THE EQUINE DIGESTIVE
SYSTEM
Types of Digestive Systems
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Monogastric
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Ruminants
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simple-stomach
humans, pigs, dog, monkey
multiple stomachs
cattle, sheep, goat
Pseudo-Ruminants (Functional Cecum)
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horse, rabbit, hamster, guinea pig
IT’S A HORSE, OF COURSE
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Not a ruminant!
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Modified non-ruminant
Hind-gut fermentator
More efficient than non-ruminants in digesting
cellulose and hemi-cellulose.
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Cellulose and hemi-cellulose are found in large
quantities in roughages such as grass and hay.
HORSE DIGESTIVE SYSTEM
IT’S A HORSE, OF COURSE
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MOUTH
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Use their teeth to grab and rip the grass from the
roots.
Jaw movement is both vertical and lateral…tear
grass fibers between their jaws.
Upper jaw is wider than the lower jaw, so
mastication only occurs on one side of the mouth
at a time
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This is why the horse develops sharp points on the
inside and outside molars that require ‘floating’.
IT’S A HORSE, OF COURSE
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ESOPHAGUS
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One-way peristalic action!
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Cannot regurgitate
Do not ‘chew their cud’
Horses cannot ‘burp’ or pass gas through their
esophagus.
Because they do not ‘chew their cud’ (or re-chew
their food) the grass and hay fragments tend to be
longer.
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Poor quality, tough or stemmy hay is difficult for the
horse to tear apart and chew.
IT’S A HORSE, OF COURSE
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STOMACH
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Smallest stomach of all farm animals, in proportion
to the animals body size.
Lacks extensive muscular movement
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Food tends to layer, not mix
Does not contribute to the mechanical breakdown of food
Stomach secretes
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HCL
Enzymes
IT’S A HORSE, OF COURSE
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SMALL INTESTINE
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Horse does not have a gallbladder, so there is no
storage of bile from the liver.
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Bile is critical to the digestion of fats. In most animals it
is stored so that large quantities of fats can be
consumed and digested.
Bile is secreted directly from the liver into the
duodenum, or the first part of the small intestine.
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Makes it necessary for horse to consume small meals
several times a day
IT’S A HORSE, OF COURSE
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LARGE INTESTINE
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Accounts for 60% of the total volume of the
gastro-intestinal tract.
Divided into four parts
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Cecum
Large Colon
Small Colon
Rectum
IT’S A HORSE, OF COURSE
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LARGE INTESTINE
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Cecum and Large Colon
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Contain active bacteria similar to the microbes of the
rumen
Bacterial breakdown of cellulose and other
carbohydrates results in Volitale Fatty Acids (VFA’s)
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VFA’s are used as a source of energy by the horse, similar
to glucose or other sugars.
The bacteria also make:
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All of the water-soluable vitamins
Some proteins
IT’S A HORSE, OF COURSE
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LARGE INTESTINE
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Small Colon
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Primary area of water absorption
What does the design of the Equine
Digestive System tell us?
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Only one chewing!
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Cannot burp or regurgitate!
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Require good quality hay so that it can be ‘destroyed’ into
small digestible pieces the first time!
When the have an upset stomach or too much gas it can
only go one direction….and it has a long way to go!
Small Stomach
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Designed for several small feedings during the day.
Not very active, food tends to layer.
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Without adequate moisture…WATER, the food will not move
through to the small intestine and it will ferment.
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Fermentation = gas.
What does the design of the Equine
Digestive System tell us?
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No Gall bladder
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Majority of the digestion of fats, proteins and
carbohydrates occur in the small intestine
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Not prepared for a large meal…again, designed for several
small meals during the day.
The small intestine is before the large intestine!
The grass and hay that is consumed is not digested
until it reaches the large intestine!
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High quality hay/grass will be more readily digested in the
large intestine and offer more nutrients for absorption in the
small intestine.