Forestomach Digestion I Flashcards
(30 cards)
What are the digestable components of a plant cell?
Carbohydrates (suagrs, starches, fibers), proteins, and lipids.
Which part of the plant cell wall is digestable only by microbial enzymes?
Cellulose, hemicellulose and pectin
What enzyme is required to digest cellulose and who produces it?
Cellulase, produced by fungi, bacteria, and protozoans (not mammals)
What is the primary energy source abdorbed by the host from fermentation?
Volatile fatty acids (VFAs)
What are the prerequisites for fermentation in the rumen?
Substrate (feed), anaerobiosis, temperature, pH, microbial biomass, rentention time, and waste removal.
What are the main microbial groups in the rumen?
Bacteria, protozoa, fungi, archaea, and viruses
How does fermentation rate compare between sugars, starches, and fibers?
Sugars > Starches > Fibers
What is the clinical risk of a high-starch diet in ruminants?
Rumen acidosis due to excessive lactic acid production.
What is microbial yield and why is it important?
Microbial biomass produced per mass of substrate used; it supports host nutrition.
How do microbes contribute to host protein nutrition?
Microbial biomass is digested by host enzymes, providing high-quality protein.
What happens in urea/ammonia toxicosis?
Excess urea leads to NH3 accumulation, which is neurotoxic and disrupts the Krebs cycle.
How do protozoa help prevent rumen acidosis?
They ingest suagrs and lactic acid, reducing acid buildup.
What is the role of methanogens in the rumen?
Convert to H2 to CH4 preventing fermentation inhibition from hydrogen accumulation
What does the C:N ratio indicate in rumen nutrition?
Optimal microbial growth occurs at a C:N ration of 20-30; imbalance affects yield or causes toxicosis
What is the function of the reticulo-omasal orifice?
Regulates retention time to allow sufficient fermentation.
What are the three main VFAs produced during fermentation?
Acetate, propionate, and butyrate
What is the typical pH range of the rumen environment?
5.5 to 6.7
What is the function of lipolytic bacteria in the rumen?
Hydrolyze dietary lipids into glycerol and fatty acids.
Why might fat supplementation decrease milk production in ruminants?
Lipids can interfere with fiber fermentation by making fiber less accessible to microbes.
What are the effects of excess lactic acid in the rumen?
Rumen pH drops, killing fiber-digesting microbe and causing acidosis.
What is the role of lactate-degrading bacteria like Selenomonas?
Metabolize lactic acid to prevent acidosis
How much of the host’s protein needs can be meet by microbial biomass?
60-85%
What happens to microbial biomass after leaving the rumen?
It is digested by lysozyme and host enzymes in the abomasum and small intestine.
What role do rumen fungi play in digestion?
They penetrate plant tissues and help digest lignocellulose.
