Digestion by yurtgc548

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									Digestion

Do it or DIE
                  Digestion
• Digestion is the process of breaking down feed
  into simple substances that can be absorbed by
  the body.
• Absorption is taking the digested parts of the
  feed into the bloodstream
• The digestive system consists of the parts of
  the body involved in chewing and digesting feed
  – This system also moves the digested feed through
    the animal’s body and absorbs the products of
    digestion
         Four Types of Digestive
                Systems
•   Monogastric (simple)
•   Avian
•   Ruminants (polygastric)
•   Pseudo-ruminants
 Monogastric Digestive System
• A monogastric digestive system has a
  simple stomach.
               The Stomach
• The stomach is a muscular organ that
  stores ingested feed and moves it into the
  small intestine
  – The stomach secretes acid
     • Stomach has a low pH of 1.5 – 2.5
     • Destroys most bacteria
     • Breaks down feed materials
   Monogastric Animal Feeds
• The best types of feeds for monogastric
  animals are concentrated feeds
  – Grains rather than large amounts of roughage
    Types of Monogastric Animals
•   Dogs
•   Cats
•   Swine
•   Humans
      Avian Digestive System
• Poultry digestive tract
              Avian Digestion
• No Teeth = No Chewing
  – The feed is emptied from the mouth directly
    into the Crop
     • The crop is where the food is stored and soaked
  – Feed leaves the crop, passes through the
    proventriculus, which is similar to a normal
    stomach, and into the gizzard
     • The gizzard is a very muscular organ, which
       contains stones or grit
        – The gizzard is a bird’s teeth
 Polygastric or Ruminant Digestive
              System
• Large stomach divided into compartments
• Designed for food to be ingested,
  eructated, chewed, and swallowed again
         Polygastric Structure
• The largest section of the stomach is the Rumen
  – Contains bacteria and other microbes to cause
    fermentation
• The reticulum is the section of the stomach that
  causes eructation or “Belching”
  – Also known as the “Hardware Stomach” because it
    collects foreign objects such as stones or nails
• The third section is the Omasum
  – Filters substances and removes water
• The last section is the Abomasum
  – Secretes gastric juices
  – Similar to the true stomach in a monogastric animal
         Pseudo-ruminant
• Animals that eat large amounts of
  roughage, but do not have several
  compartments in the stomach are pseudo-
  ruminant animals
        Pseudo-ruminant
– Digestive system does some of the same
  functions as those of ruminants
– Able to digest large amounts of roughage
  because of a greatly enlarged cecum and
  large intestine
– Examples of pseudo-ruminants are horses,
  rabbits, guinea pigs, and hamsters
   Basic Structure of the Digestive
               System
• The mouth
   – Contains teeth, except birds, a tongue, and salivary glands
      • Teeth
          – Grind feeds in a process called mastication
          – Ruminants only have bottom teeth and a hard dental plate at
             the top
          – All have molars on top and bottom
      • Tongue
          – Contains taste buds to help determine which feeds are edible
          – Aids in moving feeds around to the teeth and esophagus
      • Salivary glands
          – Are activated when an animal is hungry or smells feed
          – Secrete a watery substance to help break down feeds into a
             mash
          – Some animals contain enzymes
  Basic Structure of the Digestive
              System
• The esophagus
  – A hollow muscular tube leading from the
    mouth to the stomach
    • Moves feed by peristalsis
   Basic Structure of the Digestive
               System
• The stomach
   – A muscular organ which grinds feeds, adds
     digestive juices, and removes some water
   Basic Structure of the Digestive
               System
• The small intestine
   – Probably the most important digestive organ,
     since this is where most absorption of nutrients
     takes place
   – The first division of the small intestine is the
     duodenum, which is where bile and digestive
     juices are added
       • Bile is a substance secreted by the liver to help
         digest fat
           – Bile is stored in the gall bladder, where it
             leads to the duodenum
   Basic Structure of the Digestive
               System
• The large intestine
   – Some absorption takes place here
   – Mostly water is removed
   – In pseudo-ruminants the large cecum holds
     undigested feeds for fermentation
• The rectum
   – Prepares waste for expulsion
• The anus
   – Final organ in the digestive system
   – Contains a sphincter muscle which remains
     closed until bowel movement

								
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