Animal Digestive Systems

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Animal Digestive Systems
Topic 3024Ms. Blakeley

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Digestive System Objectives

• Describe and understand the basic functions of
  the primary components of the digestive system.
• Compare the functions and locations of the
  digestive organs in man, poultry, horses, cows
  and swine.
• Differentiate between and identify digestive
  systems of man, horses, swine, poultry and cows.

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Digestive System

• Where large complex molecules are broken down
  into simpler molecules
• Digestive Tract
• Long tube beginning with mouth and ending with
  the anus
• Polygastric (Ruminant)
• A stomach with more than one compartment
• (cows, sheep, deer)
• Monogastric (Non-ruminant)
• A stomach with one compartment
• (swine, horses)
• Avian (Poultry)
• No true stomach
• (chickens, geese)

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Digestive Systems

• Man Pig have a simple stomach with an extensive
  intestinal system
• Horses Rabbits have a simple stomach with an
  extensive intestinal system and an enlarged
  caecum
• Ruminants have a complex stomach with a simpler
  intestinal system
• Poultry have no teeth and no true stomach with a
  crop and gizzard to grind food

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Mouth Esophagus

• Mouth prehensile tool (grasps mixes food)
• Chewing breaks down food
• Salivary Glands secrete juices containing enzymes
  (digest food)
• Mucin lubricates the feed for swallowing
• Esophagus muscular tube that connects mouth to
  stomach
• Peristaltic waves send feed down the esophagus,
  (muscle contractions).
• Reverse Peristalsis blowing chunks
• The cardia, located at the end of the esophagus
  prevents feed in the stomach from coming back
  into the esophagus. ( non-ruminants only)

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Simple Stomach

• Muscular organ, receives feed
• Gastric juices are secreted by the glands in the
  stomach wall
• start when masticated feed enters the stomach
• Gastric juices have about 0.2 to 0.5 percent HCl
• The wall of the stomach is lined with muscle,
  this muscle churns and squeezes the feed
• This action forces the liquid portion on into the
  small intestine

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Ruminant Stomach

• Occupies 3/4 of abdominal cavity, mostly on the
  left side
• Rumen (paunch) 80 of stomach, lighter food
  collects here
• Microbes digest cellulose
• Uses lots of water
• Reticulum (hardware stomach) 5 of stomach,
  heavy foreign items are trapped here

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Ruminant Stomach (cont.)

• Omasum (many plies) 8 of stomach, absorbs water
• Abomasum (true stomach) 7 of stomach, typical
  enzyme activity
• Rumination regurgitation, re-chewing of food

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Rumination (regurgitation)

• After rumen if full, it lies down to ruminate
  (chew its cud)
• Cattle spend from 5-7 hours ruminating, broken up
  into 6-8 periods
• Regurgitation is the process of forcing the feed
  back into the mouth for chewing
• Done through a series of muscular contractions
  and pressure in the rumen and reticulum

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Avian stomach/gizzard

• Since chickens have no teeth, they swallow food
  whole and its stored in the crop
• Feed in proventriculus are secreted by the
  glandular stomach and mixed with feed
• The feed moves to the gizzard and is ground
• Epithelium breaks the feed into smaller
  particles, further mixing proventricular digestie
  juices with the feed in the gizzard
• The end of the digestive system is the vent

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Small Large Intestines

• Small Intestine long coiled tube connecting
  stomach to large intestine
• rest of the digestion and absorption takes place
  here
• surface covered with villi (surface area)
• Large Intestine Caecum, colon, rectum
• absorbs water (makes feces more solid)
• some vitamins minerals absorbed here
• Cecal Fermenters (Horse) similar to rumen

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