Ruminant Digestive System

• What is a ruminant?
    * Ruminants are animals that have one stomach with four compartments. The compartments are as follows:
      * Rumen
      * Reticulum
      * Omasum
      * Abomasum

• Four Compartments
    * Rumen
      * Largest compartment
      * Storage and fermentation
      * Located on left side of the cow
    * Reticulum
      * Resembles honeycomb
      * Separated only slightly from the rumen
      * Heavier objects are caught in this area
      * Source of “hardware disease”
    * Omasum
      * Often called “many-piles,” since it is layers of tissue that resemble pages in a book
      * Water/liquid absorption
    * Abomasum
      * Referred to as the “true stomach”; similar to the stomach in a monogastic
      * Has hydrochloric acid and a glandular lining
      * Digestive enzymes are introduced here
• Digestive Pathway https://www.youtube.com/watch?v=SVNNJf_28KE
    * Food is ingested through the mouth. Cows are unique. They possess a dental pad instead of top teeth. The food is grasped by the tongue and ripped off. Food is broken into smaller pieces, mixes with saliva and is swallowed
    * Food moves down the pharynx or throat and through the esophagus
    * Esophagus, a long narrow tube connecting the throat to the stomach. Peristalsis (wavelike contraction) helps propel the food.
    * Food then moves into the rumen, the holding vat. Beneficial bacteria break down and digest the food, and papillae, “finger-like projections,” absorb nutrients that are created from the bacteria

    *
    * Cows lack digestive enzymes to digest plant material directly due to their inability to break down cellulose
    * The rumen possesses billions of beneficial bacteria that digest feed the cow had eaten
      * The feed is fermented, and volatile fatty acids, proteins and B vitamins are produced
      * The rumen in a cow can hold up to 50 gallons of digested feed
  * The reticulum is only slightly separated from the rumen. Food passes back and forth
    * Filtering occurs, keeping particles inside the rumen
  * Food is then passed back up to the esophagus and throat as a bolus, a small mass of food. This is referred to as “cud”
  * Saliva, a critical component of cud chewing, buffers the rumen. This is similar to taking an antacid
    * Cows produce up to 50 quarts of saliva daily
  * Food repasses into the reticulum and backflows between the reticulum and the rumen for further digestion. Then it passes into the omasum
  * The “cud” passes into the omasum
    * Primary purpose is water absorption and absorption of substances from digestion
    * This organ is lacking in modified ruminants/pseudoruminants
  * The abomasum functions similarly to the mongastric stomach
    * Acids, buffers, and enzymes break down food
  * Food continues on into the small intestine where nutrient absorption and water absorption occur
    * Enzymes are secreted in the from the pancreas and liver
    * Three portions in the small intestine: duodenum, jejunum, ileum
  * Food continues on into the cecum, the first part of the large intestine. Food continues through the large intestine to the colon at the far end
  * From the colon it is excreted through the rectum. Undigested food and body wastes are eliminated through the anus, the opening of the rectum

• Modified Ruminants
    * Modified ruminants are animals that have one stomach with three compartments
      * The compartments are as follows:
        * C1 -- similar to the rumen
        * C2 -- similar to the reticulum
        * C3 -- similar to the abomasum
    * Include the camel, alpaca, and hippopotamus
• Ruminant Feeds
    * Eat roughages or forages
      * Forages include hay, pasture, and corn silage
    * Concentrates are often in the form of grains