ANIMAL DIGESTIVE SYSTEMS

ANIMAL DIGESTIVE SYSTEMS

1. NON-RUMINANTS

   • Monogastrics
     • is characterized by a simple glandular stomach
       • have a full set of teeth, unlike ruminants that lack superior incisors.
         • Humans, pigs and carnivores have monogastric digestive systems.
           • the food enters the small intestine where is found with bile (from the liver) and more enzymes from the pancreas and the intestines themselves.
             • The materials, or waste products, that cannot be absorbed are retained in the large intestine, become faeces and are excreted through the animal's anus.
               • Other waste products of the blood are excreted by the kidneys as urine and exhaled as gas during breathing

2. the digestive tract is a tube that runs from the mouth to the anus, along that tube are, the mouth, stomach, small intestine, large intestine and anus.

3. Non-Ruminant Herbivores

   • Horses (and related species) and rabbits
     • It contains a microbial population in most animals
       • Hindgut fermentors spend more time chew the food than monogastric animals.
         • The stomach is comparatively small
           • most of the digestion of fats, proteins and non-fibrous carbohydrates takes place in the small intestine.
             • Nutrient absorption is limited in the large intestine, but the absorption of volatile fat

4. Avian

   • Birds are classified as having a monogastric digestive system
     • birds just have a beak which they use to peck or grab and take
       • area of the esophagus that acts as a reservoir to store food.
         • the digestive tract of birds is composed of the reservoir, the proventriculus.
           • From the proventriculus, feed enters the gizzard
             • The gizzard will retain "grit" as small stones that the bird eats, which it uses to help grind up the food.

5. RUMINANTS

   • Ruminants have no upper incisor teeth.
     • The digestive system of ruminants is characterized by a four-compartment system
       • The first compartment is the reticle followed by the rumen. The two interconnected The compartments are called the reticulum-rumen, which makes it the largest ruminant compartment stomach. The rumen is followed by the omasum and the abomasum.
       • Cattle, sheep and goats have the digestive system of ruminants.
       • the food is diluted with large amounts of saliva (cattle can produce up to 150 litres per day)
         • The rumen typically has two layers
           • a lower liquid layer where the finest particles are suspended
           • a drier top layer of thicker solid material
         • The rumen content is continuously mixed by rhythmic contractions of the the rumen walls.
           • During rumination, the feed material in the reticulum near the oesophageal opening is drawn into the esophagus and sent by the esophageal contractions back into the mouth
             • Once back in the mouth, any liquid is quickly swallowed again, but the thicker feed material is chewed completely before being returned to the rumen for the next phase of digestion (this repetitive process is called "bolus-chewing").
               • the food is subject to a wide variety of microbes that helps plants to digest
                 • The microbes themselves are also digested and utilized as beneficial nutrients further down the digestive tract.
                   • In the abomasum, enzymes and acids are produced to help in the the breakdown of proteins and other nutrients that are consumed by the animal.
                     • in the small intestine, the absorption of nutrients occurs.
                       • As the food continues to travel through the gastrointestinal tract, as in the monogastric, it reaches the large intestine where most of the final fermentation takes place and where there is a higher absorption of water and VFAs