Rumination Flashcards
What is rumination?
The process of regurgitation, remastication and redeglutition
Describe how regurgitation occurs
Thorax expands - increased negative pressure. Cardiac sphincter opens Diaphragm contracts Reverse peristalsis into oral cavity Liquid immediately swallowed back down.
Which parts of the stomach are the forestomach? Which is the true stomach?
omasum, rumen, reticulum
Abomasum
What type of epithelium is found in the forestomach?
Stratified squamous
Describe the size and lining of the reticulum
Small
Smooth muscle
Ridges
What remains in the reticulum?
Very dense particles, stones
Where does long grass/hay/straw float? Where does gas collect
Hay - bottom of dorsal sac
gas - top of dorsal sac
Why are the stomach chambers less defined in browsers?
More rapid fermentation through rumen and reticulum
How many times does rumination occur per day
6-10
Which is the main fermentation chamber?
Rumen
What separates the rumen into dorsal and ventral sac
Longitudinal groove
What does the vertical groove seperate the rumen into?
Caudodorsa and ventral blind sac
What increases the surface area of the rumen? Does it contain smooth muscle?
Papillae
No
What regulates the contraction of the rumen?
Short reflexes\
Via vagus nerve
Which side of the body is the omasum on? What structure does the omasum have?
Right
Multiple leaves with papillae
What regulates the passage of fermented material from reticulum to omasum?
Reticulo-omasal orifice
What type of cells line the abomasum?
Columnar epithelial cells
Glands
There is a constant flow from the rumen to the abomasum. The pH is higher than the simple stomach, but is still acidic enough to kill microbes. Why is it less acidic?
Alkaline fermentation fluid
What are the 2 types of rumino reticulum contractions?
Primary - mixing
Secondary - eructation
During rumination, which contractions precede primary ones?
Extra reticular contactions
What are the 4 stages of primary contractions?
First reticular contraction
Second reticular contraction
Dorsal rumen contraction
Ventral rumen contaction
How many litres are eructed per day due to fermentation?
2000-4000
When can eructation not occur?
When animal lying on side
Gastric torsion
Describe the process which leads to eructation?
Thorax expands - negative pressure
Most gas inhaled, some escapes
WHat happens if there is failure to eructate? What might cause this?
Bloating
Oesophageal obstruction, tumour, eating clover
What is frothy bloat?
bloat caused by smaller bubbles that don’t group into larger bubbles
What can the pressure of bloating cause?
Cardiac/respiratory distress
Which NS regulates forestomach motility? WHich nerve? Where is the control centre?
Autonomic
Vagus
Medulla
Which part of the stomach is developed at birth? When does the other part do stomach?
Abomasum
Forestomach develops when eating roughage, 2-3 weeks
What stimulates fermentation microbes to develop?
Mothers licking
Ingestion
How does milk bypass the fermentation chamber? What stimulates this?
Oesophageal groove.
Warm milk
What happens if there is too much milk or oesophageal groove failure?
Lactose fermented to lactic acid
Upsets microbes
What is microbial fermentation? What conditions is it in?
Chemical breakdown of food to VFAs by microbes
What would happen if microbial fermentation was an aerobic process/
Food would be fully broken down to CO2 and H20
No energy would be provided to host
What does the ruminoreticulum do?
Provide environment for microbes
Slow down transit time
How does oxygen gain entry into the stomach?
Through blood
Through swallowed air
Microbial fermentation is only 90% efficient. Why is this?
10% lost by methane production
What type of organisms are found in microbial fermentation
Bacteria - amylolytic, cellulolytic, proteolytic, methanogenic, lactate utilisers
Large Protozoa - less efficient
Fungi - aerobic
Describe the movement of water, ammonium ions and VFAs in the stomach
Ammonium ions taken up by microbes
Water enters rumen
VFAs absorbed by host
What is rumen acidosis? Why is this bad? How is it treated?
Sudden increase of H+ due to VFAs (too much hCHO)
Damages epithelium, causes water absorption into rumen —> dehydration
Alkaline IV fluid
Which molecules are not available to the host, due to being taken up by microbes?
Monosaccharides
Di/tri peptides
AA
Which is the only VFA that can be used in gluconeogenesis? how is it formed?
Propionate
Anaerobic glycolysis of pyruvate
What can non-protein nitrogen be used for?
Protein synthesis via microbes
Non protein nitrogen is essential. How much is found in grass? What about haylage?
15%
70% due to fermentation
