Flashcards in Final Exam GI Physiology: Ruminant Digestion Deck (56)
What is the principal distinguishing characteristic of ruminant digestion?
Fermentation of ingesta by microbes in the ruminoreticulum
What is fermentation?
The anaerobic oxidation of substrate followed by reduction of an organic molecule
Lactate formed from pyruvate is an example of what?
Methane formed from CO2 is an example of what?
Fermentation of amino acids yields what products?
Sulfates and Nitrates
What products are produced when sulfates and nitrates are reduced?
In regards to fermentation of carbohydrates, put the following in order from which ferments fastest to which ferments slowest:
Simple sugars RAPID
What are the products of fermentation of simple sugars, starches, and cellulose (carbohydrates)?
T or F: Microbes can perform oxidation in the absence of oxygen.
What enzyme is utilized by microbes in the rumen to oxidize pyruvate to acetyl CoA?
What enzyme in the rumen acts on the acetyl CoA produced?
Adds Pi to Acetyl CoA --> Acetyl-Pi and Coenzyme A
What enzyme in the rumen is used by microbes along with ADP to act on Acetyl-Pi produced earlier?
Acetyl-Pi + ADP ---acetate kinase---> acetic acid + ATP
What are the waste products of carbohydrate fermentation?
Volatile Fatty Acids!
How do anaerobic microbes generate ATP?
By glycolysis and microbe-enzyme reactions in the rumen
In the rumen/reticulum, what are O2 and CO2 ultimately reduced into?
H2O and CH4
The ratio of VFA : Lactic acid is a function of ______ .
A low VFA : Lactic Acid (and therefore low rumen pH) ratio is indicative of what kind of diet?
High % of easily digestible carbs
What ruminal pH is considered normal?
pH of 6
What is a dietary cause of Ruminal Lactic Acidosis?
A low VFA : Lactic Acid ratio (caused by too much easily digestible carbs in diet)
What conditions can Ruminal Lactic Acidosis lead to?
Ulceration, pain, going off feed, systemic ketoacidosis
How is protein digested in the rumen?
Through microbial digestion and hydrolysis via pancreatic and brush border enzymes
What do microbes do to proteins in the rumen?
Hydrolysis of protein --> amino acids
Hydrolysis of amino acids ---deamination---> VFA
What is generated as a result of amino acid deamination to VFA?
What is produced Ammonia utilized for?
To make microbial protein
To be converted into urea by the liver
What % of protein escapes microbial digestion?
The 50% of protein that escapes microbial digestion is hydrolyzed in the _______ and _________ via pancreatic and brush border enzymes.
Abomasum and Small Intestine
Protein hydrolyzed by pancreatic and brush border enzymes yield what products?
Small peptides and amino acids
Where are dead microbes digested?
Abomasum and small intestine
Where can urea be found after it is produced by the liver?
Urea can diffuse into GI tract lumen
Urea can be secreted by salivary glands