rumen fermentation

Question 1

list food derived monosaccharides

carbohydrates

Answer 1

hexoses: glucose, fructose, galactose, mannose
pentoses: arabinose, Xylose

Question 2

list food derived disaccharides

Answer 2

• sucrose
• lactose
• maltose
• cellobiose (cant be split by mammalian enzymes but can be split by microbial enzymes)

Question 3

what features permit continuous fermentation in the adult rumen

Answer 3

• 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

Question 4

how do ruminants digest protein

Answer 4

• 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

Question 5

why dont ruminants need dietary essential amino acids

Answer 5

the rumen microbes synthesize all amino acids including essential ones from non-protein nitrogen sources (urea)

Question 6

what is protein cycling in the ruminant

Answer 6

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

Question 7

digestion of carbohydrates in the rumen produces what

Answer 7

volatile fatty acids
- acetate
- propionate
- butyrate

Question 8

digestion of protein by the rumen produces what

Answer 8

• microbial protein
• small peptides

Question 9

in addition to volatile fatty acids and proteins, what other compounds are produced by fermentation in the rumen

Answer 9

• B vitamins
• vitamin K
• methane
• carbon dioxide

Question 10

what are the advantages to rumen fermentation

Answer 10

• 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

Question 11

what are the disadvtanges to ruminant fermentation

Answer 11

• 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)

Question 12

what is the impact of a forage based diet on rumen fermentation

Answer 12

• high fibre –> promotes acetate (VFA) production
• supports fat synthesis
• microbial protein synthesis more efficient

Question 13

what are the impacts of a concentrate based diet on rumen fermentation

Answer 13

• high starch
• increase propionate (VFA) production
• can lead to rumen acidosis if not balanced properly

Question 14

what are the impacts of abrupt dietary changes on rumen fermentation

Answer 14

• disrupt microbial populations
• disrupts feremntation patterns
• leads to digestive disturbances

Question 15

describe the rumen environment in rumen acidosis

Answer 15

• 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

Question 16

describe the rumen environment in bloat

Answer 16

• accumulation of gase due to inability to erucate (gas bloat)
• if foam bloat (cuased by clover rich pasture) gas gets stuck in froth and cant be erucated

Question 17

chronic acidosis results in

Answer 17

• pain
• sub optimal rumen function
• reduced food intake
• indigestion
• loose feces
• low milk fat levels

Question 18

discuss how rumen fermentation diseases can be prevented

Answer 18

• feed balanced diet
• consistent feeding schedules
• gradual diet transitions
• monitoring and intervention