rumen fermentation Flashcards
list food derived monosaccharides
carbohydrates
hexoses: glucose, fructose, galactose, mannose
pentoses: arabinose, Xylose
list food derived disaccharides
- sucrose
- lactose
- maltose
- cellobiose (cant be split by mammalian enzymes but can be split by microbial enzymes)
what features permit continuous fermentation in the adult rumen
- complex microbiota which continuously break down plant materials
- anaerobic environment
- constant temp and pH
- continuous nutrient supply (frequent grazing)
- regular mixing and motility
- efficient removal of end products (VFAs and gases continuously absorbed by rumen wall or erucated)
- buffering agents (in the saliva, bicarbonate and phosphate continuously secreted and swallowed
how do ruminants digest protein
- degredation by microbes (proteins broken down by microbes into peptides and amino acids
- microbial protein synthesis (ammonia and carbon skeletons used by microbes to synthesize their own proteins)
- additional proteins that escape microbial degredation digested and absorbed in the small intestine
all microbes are capable of synthesizing all essential amino acids
why dont ruminants need dietary essential amino acids
the rumen microbes synthesize all amino acids including essential ones from non-protein nitrogen sources (urea)
what is protein cycling in the ruminant
the process by which nitrogenous compounds such as urea produced in the liver are recycled back to the rumen.
- urea enters the rumen through saliva or directly across rumen wall
- urea then hydrolyzed by microbial urease to ammonia which is utilized by microbes for protein synthesis
- enhances nitrogen efficiency and reduces the requirement for dietary protein
digestion of carbohydrates in the rumen produces what
volatile fatty acids
- acetate
- propionate
- butyrate
digestion of protein by the rumen produces what
- microbial protein
- small peptides
in addition to volatile fatty acids and proteins, what other compounds are produced by fermentation in the rumen
- B vitamins
- vitamin K
- methane
- carbon dioxide
what are the advantages to rumen fermentation
- ability to utilize fibrous plant materials that non-ruminants cant digest
- synthesis of high quality microbial protein from non-protein nitrogen soures
- production of essential vitamins by rumen microbes
what are the disadvtanges to ruminant fermentation
- production of methane (environmental concerns)
- energy losses due to fermentation and erucation
- potential for rumen acidosis if the diet is not properly managed (because bacteria digest most readily availible nutrient and produces lots of VFA if too concentrated)
what is the impact of a forage based diet on rumen fermentation
- high fibre –> promotes acetate (VFA) production
- supports fat synthesis
- microbial protein synthesis more efficient
what are the impacts of a concentrate based diet on rumen fermentation
- high starch
- increase propionate (VFA) production
- can lead to rumen acidosis if not balanced properly
what are the impacts of abrupt dietary changes on rumen fermentation
- disrupt microbial populations
- disrupts feremntation patterns
- leads to digestive disturbances
describe the rumen environment in rumen acidosis
- caused by rapid fermentation of high starch diets
- leads to drop in rumen pH as increase production of VFA too rapid for absorption
- microbial imbalance as pH disturbance can kill
