Flashcards in Rumen Motility Deck (20)
How does microbial digestion provide energy for the host?
Breaks down cellulose in cell walls of food, produces glucose/polysaccharides for glycolysis (Which produces VFAs, CO2, CH4 for host and microbes)
How does fermentation provide energy for the microbes?
Protein fermentation provides peptides for microbial growth and replication, microbial protein then utilized by host to carry out normal digestion
Name seven things that need to be correct in order for fermentation to occur.
pH, temperature (37C), substrate, anaerobic conditions, stable ionic condition, stable population of flora, and removal of non-fermentable waste
How often does primary (Mixing) contraction occur?
About every minute, more frequent if eating, absent when sleeping
How often does secondary (Eructation) contraction occur?
About half as frequently as primary contraction
How much gas is produced per minute in the rumen?
About 2 L of gas/min
What is the composition of the gas produced in the rumen?
75% CO2, 25% CH4
How is rumination, breathing, and eructation controlled in the ruminant?
By the brain stem (Vagus nerve in non-ruminants)
What afferent inputs can lead to rumination?
Mouth (Chewing), distension (Stretch receptors in walls, especially in rumen pillars), ingesta consistency/fiber length (Chopped/concentrated diet only poorly stimulates rumination), pH/VFA concentration (Low pH causes rumen stasis, grain acidosis), ionic compositions, etc.
Where is material for rumination selected from?
How are fibers selected for rumination?
Mechanoreceptors in pillars select long dietary fiber to be rechewed
What are the two fates of chewed digesta?
Can go through to omasum (If appropriate size) or can go through another cycle of contraction
How much saliva is produced per day in the cow?
What is the difference between ingestion saliva and rumination saliva?
Ingestion saliva is more mucus-filled and rumination saliva is more serous.
What provides 70% of rumen fluid?
Isotonic serous secretion from parotid duct, also has high buffering abilities and allows for urea entrance back into the rumen
Does the rumen contribute any fluid for digestion?
No, only saliva and water content in diet
Where are VFAs absorbed?
Through stratified squamous epithelium of ruminal papillae (Important for pH control)
Describe the surface epithelial cells of the rumen.
Stratified squamous with high keratinization, underneath layers metabolically active, surface Na+/H+ exchange lowers pH and promotes VFA absorption
Where is VFA absorption completed?
Leaf-like folds of the omasum