Ruminant GI Physiology and Diseases (Niehaus) Flashcards
(34 cards)
Forestomach Anatomy
List the Four stomach compartments of a ruminant:
- Rumen
- Reticulum
- Omasum
- Abomasum
Ruminant Forestomach Anatomy:
- Largest stomach compartment in the adult
- “Fermentation vat”
- Microbes break down complex carbs
- Bacteria
- Protozoa
- Fungi
- Lined by papillae which increases surface area for absorption
- (not smooth)
Rumen
Ruminant Forestomach Anatomy:
- Aka. Hardware Stomach
- Honeycomb lined
- Cranial outpouching of rumen – collectively known as rumenoreticulum
Reticulum
- Cranioventral abdomen, adjacent to diaphragm
- Heart adjacent to diaphragm on other side
Ruminant Forestomach Anatomy:
- Right cranial abdomen
- Multiple leaves (“pages in a book”)
- Conduit b/w rumen and abomasum
- Absorbs water, electrolytes, VFA’s
Omasum “Butcher’s Bible”
Ruminant Forestomach Anatomy:
- The True Stomach
- Right ventral abdomen
- Glandular mucosa
- Secretes HCL (fundic region)
- Pepsinogen (pyloric region)
- Mucus (pyloric region)
- Largest compartment in calf and decreases in relative size as the animal matures
Abomasum
Innervation and Blood Supply:
- Arterial supply from ___(a)___
- Portal system
- Transport VFA’s and ammonia from rumen to liver
- Vagus Nerve (CrN 10)
- Dorsal trunk – __(b)__
- Ventral Trunk – ___(c)___
(a) Celiac - cranial mesenteric trunk
(b) Rumen
(c) Omasum, abomasum, reticulum
- Known as:
- Rumeno-reticulo groove
- Gastric groove
- Function:
- Diverts milk directly to the abomasum
- Suckling stimulates closure
Esophageal Groove
Rumen Bacteria:
- Methane-producing bacteria
- Regulate overall fermentation by removal of hydrogen
- As H2 is removed, H2 producing species proliferate
Methanogens
- > 100 species; Diet affects distribution
- Majority are ciliates
- They ingest bacteria
- Intraruminal Nitrogen recycling
Rumen Protozoa
- degrade cellulose and xylans
- Contribute to fiber degradation and facilitate bacterial colonization
- Can become pathologic - mycotic rumenitis
Ruminal Fungi
Advantages:
- Energy from fibrous materials
- Microbes - amino acid source
- Produce B-vitamins
Disadvantages:
- Inefficient use of nutrients (starch, sugars, proteins)
- Biologic value of high-quality proteins decreased
- Fermentation can get out of control
These are the advantages & disadvantages of…
Pregastric Fermentation
- Provide 80% of the host’s energy needs
- Produced in the rumen in absorbed through the rumen wall
Volatile Fatty Acids
(T/F) Microbes and undigested feed material move to abomasum and are broken down as protein source for host
True
Causes:
- Esophageal obstruction
- Rumen Motility disorders
- Fluid/Foam at cardia
- Recumbency
- Frothy Bloat
Effects
- Push on diaphragm inhibiting respirations -> dyspnea -> death
- Rumen stretch can inhibit motility -> further gas accumulation
Rumen Tympany
Rumen Tympany:
- Physical obstruction prevents gas from eructation
- Passage of tube relieves bloat
Free Gas Bloat
Rumen Tympany:
- Thick foam cannot be eructated
- Foam will not pass through tube
Frothy Bloat
- Results in free gas bloat
- Signs
- Dysphagia
- Drooling
- Acidosis
- May palpate the mass neck
- Intraluminal vs. Extraluminal obstruction
- Cattle vs. Small Ruminants
Choke (Esophageal obstruction)
- Gasses of fermentation stay within the ingesta and don’t coalesce
- Lush legumes & high concentrate diets
- Rapid digestibility -> Microbial proliferation -> Multiplying bacteria release mucopolysaccharide (slime/biofilm)
- Small gas bubbles trapped in slime
- Saliva has foam-retardant properties
Frothy Bloat
What is the treatment for Frothy Bloat?
- Poloxalene => breaks down foam
- Rumenotomy
- Relief of CHRONIC bloat
- Seal created b/w rumen and skin
What can disturbances of Vagal innervation lead to?
proximal GI dysfunction
- Dysfunction of the forestomach compartments due to compromise of vagal innervation. Rumen distension -> abdominal distension (“Papple”)
Vagal Indigestion
List the four classifications of vagal indigestion:
- Failure of eructation – Free gas bloat
- Omasal transport failure (anterior functional stenosis) – true forestomach disease. Most common form of vagal indigestion. Rumen distends w/o abomasal distension
- Pyloric outflow obstruction (posterior functional stenosis) – internal vomiting (reflux of abomasal contents into rumen). Abomasum distends first followed by omasum, then rumen
- Indigestion of late pregnancy
What type of lesions can cause interference with the vagal nerve?
Any lesion of the pharynx, neck, thorax, & cranial abdomen.
List the Signs for Vagal Indigestion:
- “Papple” shaped abdominal contour
- Low heart rate
- Hypermotile but weak ruminations
- Scant feces
- Passage of undigested feedstuff in manure
