Rumen Fermentation and Function

Question 1

Consortia

Answer 1

Groups of microbes with a common net feeding strategy

Question 2

Rumen liquor

Answer 2

Rumen liquid

Question 3

What are the 4 compartments of the rumen

Answer 3

Rumen, reticulum, omasum and abomasum

Question 4

The rumen functions as…

Answer 4

A fermentation vat

Question 5

What is the capacity of an adult dairy cows rumen

Answer 5

184L

Question 6

What is the function of papillae

Answer 6

Absorption of VFAs

Question 7

What are the 5 sacs of the rumen

Answer 7

Cranial, dorsal, ventral, caudo-dorsal and caudo-ventral

Question 8

Ruminal pillars divide…

Answer 8

The dorsal and ventral ruminal sacs

Question 9

The coronary pillars divide…

Answer 9

The caudal blind sacs

Question 10

Cranial pillar divides…

Answer 10

The dorsal and cranial sacs

Question 11

Where does the most absorption occur in the rumen

Answer 11

The ventral part of the cranial and ventral sacs (where papillae is most dense)

Question 12

What is a distinguishing feature of the reticulum

Answer 12

The honey combed shaped internal projections (trap foreign materials)

Question 13

What separates the rumen from the reticulum (only partially)

Answer 13

Reticulo-ruminal fold

Question 14

Where does the esophagus terminate

Answer 14

The cardia

Question 15

What is the function of the reticulum

Answer 15

Moves food into the rumen or omasum and aids in regurgitation of ingesta during rumination

Question 16

Where does the reticulum connect with the omasum

Answer 16

Reticulo-omasal orifice

Question 17

What is the function of the omasum

Answer 17

Retention of feed in the rumen, absorb water and reduce size of food, control passage of food and some absorption

Question 18

What is a property of the inside of the omasum

Answer 18

Has membranous folds that act as a sieve/filter (referred to as manyplies)

Question 19

What is another name for the absomasum

Answer 19

True stomach

Question 20

What is the normal pH of the rumen

Answer 20

5.5-7.5

Question 21

What are some things that help stabilize the pH in the rumen

Answer 21

Phosphate and bicarbonate in the saliva
Rapid absorption of VFAs
Drinking water and saliva help dilute the rumen liquor

Question 22

What type of diet promotes a higher rumen pH

Answer 22

High-forage diets

Question 23

What diet decreases rumen pH

Answer 23

High grain diets

Question 24

What is the osmolality of the rumen

Answer 24

Slightly under that of the blood

Question 25

How is an anaerobic environment maintained in the rumen

Answer 25

Facultative anaerobic bacteria

Question 26

What are 3 ways fermentation end products are continuously removed from the rumen

Answer 26

Passage of digesta to omasum Absorption through the rumen wall Eructation of CH4 and CO2

Question 27

What are the general two phases of contents in the rumen

Answer 27

Lower liquid phase (finer food particles) and dried upper layer (coarser solid material)

Question 28

What are three phases that materials entering the rumen can be in

Answer 28

Gas phase, floating rumen mat, liquid phase

Question 29

Heavy feed falls into...

Answer 29

The reticulum

Question 30

Light feed falls into...

Answer 30

The rumen proper

Question 31

The floating or rumen mat contains...

Answer 31

Recently consumed feed, fibrous material | may be absent in diets high in concentrate

Question 32

The liquid phase contains...

Answer 32

Smaller, dense particles (constant volume)

Question 33

What are 3 types of contractions that occur in the cows rumen and reticulum

Answer 33

Mixing, eructation, and regurgitation

Question 34

How are contractions of the rumen stimulated

Answer 34

Response to vagal sensory afferent information and initiation by vagus efferent nerves

Question 35

What is the purpose of eructation contractions

Answer 35

Expel gas from the rumen, the contractions allow it so that gas can enter the esophagus and then the trachea and lungs, so that it is expelled in the next exhale

Question 36

What help initiates the regurgitation reflex

Answer 36

The presence of a rumen mat (because its usually larger material that needs to be rechewed)

Question 37

What are 3 populations in which rumen bacteria are found

Answer 37

Loosely/firmly attached to feed particles (majority) In the rumen liquor Attached to rumen epithelium (about 1%)

Question 38

Cellulolytic bacteria

Answer 38

Produce extracellular cellulase, abundant in hay diets

Question 39

Hemicellulolytic bacteria

Answer 39

Use hemicellulose

Question 40

Amylolytic bacteria

Answer 40

Predominate with grain diets, significant proteolytic activity

Question 41

Proteolytic bacteria

Answer 41

Utilize amino acids as primary energy source

Question 42

Sugar utilizing bacteria

Answer 42

Use mono and disaccharides

Question 43

Acid utilizing bacteria

Answer 43

Use Lactic/succinic acids to form propionate, mainly in high grain diets

Question 44

Methane producing bacteria

Answer 44

Also known as archea

Question 45

Cellulolytic bacteria: growth requirements and fermentation end products

Answer 45

Require: cellulose, hemicellulose, pectin - need a high rumen pH Product: acetate, butyrate, H2, CO2

Question 46

Amylolytic bacteria: growth requirements and fermentation products

Answer 46

Require: sugar, starch, peptides, AA - need a lower pH (5.7) Products: Propionate, butyrate, acetate, lactate, H2, CO2

Question 47

What are the two families of protozoa in adult ruminants

Answer 47

Holotrichs and oligotrichs

Question 48

Holotrichs

Answer 48

Ovid organisms covered with cilia, store sugars until they burst

Question 49

Oligotrichs

Answer 49

Include many species that vary considerably in size, shape and appearance store starch

Question 50

What is the interaction between protozoa and methanogens in the rumen

Answer 50

Rumen methane bacteria attach and live on the surface of rumen protozoa for access to hydrogen

Question 51

Protozoa do not...

Answer 51

Easily pass from the rumen

Question 52

Fermentation end products of holotrichs

Answer 52

Acetic acid, butyric acid, lactic acid and H2

Question 53

Fermentation end products of oligotrichs

Answer 53

CO2, H2, acetic acid and butyric acid

Question 54

Protozoa ingest...

Answer 54

Rumen bacteria as a source of protein (contributes to rumen protein turnover)

Question 55

What are two phases of the fungi in the rumen

Answer 55

Motile phase (zoospore) and vegetative phase (sporangium)

Question 56

Under normal conditions, the rumen fungi colonize...

Answer 56

Highly lignified fibrous material

Question 57

What is the primary protein supply for ruminans

Answer 57

Microbial protein

Question 58

How much of the animals energy needs are provided by VFAs

Answer 58

greater than 70%

Question 59

Mature fibrous forages give rise to VFA mixtures with a high proportion of...

Answer 59

Acetic acid

Question 60

Less mature forages give rise to VFA mixtures containing a high proportion of...

Answer 60

Propionic acid

Question 61

VFAs are absorbed across...

Answer 61

The forestomach walls

Question 62

VFA absorption is higher when...

Answer 62

Ruminal pH is reduced (more things present as undissociated acids) Chain length increases

Question 63

What is the venous drainage of the rumen

Answer 63

The hepatic portal vein, which goes into the liver

Question 64

Lactic acid is produced during...

Answer 64

The degradation of starch

Question 65

Unmetabolized lactic acid will cause...

Answer 65

Metabolic acidosis

Question 66

How are the rumen gases removed

Answer 66

Eructation and respiration

Question 67

Carbon dioxide accounts for how much of the gases produced by microbes?

Answer 67

60%

Question 68

The fermentation of forages creates __ heat than the fermentation of concentrate feeds

Answer 68

More

Question 69

Lactic acid is produced by...

Answer 69

Amylolytic bacteria

Question 70

How does decreased rumen pH cause ruminal acidosis

Answer 70

Cellulolytic bacteria die, which release endotoxins that enter the blood and can cause shock The increase in acid can also damage the rumen epithelium

Question 71

What can cause ruminal acidosis

Answer 71

A sudden switch to a high grain diet (instead of slowly over time)