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Animal Nutrition & Metabolism > Rumen Fermentation and Function > Flashcards

Rumen Fermentation and Function Flashcards

1
Q

Consortia

A

Groups of microbes with a common net feeding strategy

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2
Q

Rumen liquor

A

Rumen liquid

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3
Q

What are the 4 compartments of the rumen

A

Rumen, reticulum, omasum and abomasum

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4
Q

The rumen functions as…

A

A fermentation vat

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5
Q

What is the capacity of an adult dairy cows rumen

A

184L

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6
Q

What is the function of papillae

A

Absorption of VFAs

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7
Q

What are the 5 sacs of the rumen

A

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

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8
Q

Ruminal pillars divide…

A

The dorsal and ventral ruminal sacs

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9
Q

The coronary pillars divide…

A

The caudal blind sacs

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10
Q

Cranial pillar divides…

A

The dorsal and cranial sacs

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11
Q

Where does the most absorption occur in the rumen

A

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

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12
Q

What is a distinguishing feature of the reticulum

A

The honey combed shaped internal projections (trap foreign materials)

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13
Q

What separates the rumen from the reticulum (only partially)

A

Reticulo-ruminal fold

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14
Q

Where does the esophagus terminate

A

The cardia

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15
Q

What is the function of the reticulum

A

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

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16
Q

Where does the reticulum connect with the omasum

A

Reticulo-omasal orifice

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17
Q

What is the function of the omasum

A

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

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18
Q

What is a property of the inside of the omasum

A

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

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19
Q

What is another name for the absomasum

A

True stomach

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20
Q

What is the normal pH of the rumen

A

5.5-7.5

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21
Q

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

A

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

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22
Q

What type of diet promotes a higher rumen pH

A

High-forage diets

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23
Q

What diet decreases rumen pH

A

High grain diets

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24
Q

What is the osmolality of the rumen

A

Slightly under that of the blood

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25
Q

How is an anaerobic environment maintained in the rumen

A

Facultative anaerobic bacteria

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26
Q

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

A

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

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27
Q

What are the general two phases of contents in the rumen

A

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

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28
Q

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

A

Gas phase, floating rumen mat, liquid phase

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29
Q

Heavy feed falls into…

A

The reticulum

30
Q

Light feed falls into…

A

The rumen proper

31
Q

The floating or rumen mat contains…

A

Recently consumed feed, fibrous material

may be absent in diets high in concentrate

32
Q

The liquid phase contains…

A

Smaller, dense particles (constant volume)

33
Q

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

A

Mixing, eructation, and regurgitation

34
Q

How are contractions of the rumen stimulated

A

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

35
Q

What is the purpose of eructation contractions

A

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

36
Q

What help initiates the regurgitation reflex

A

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

37
Q

What are 3 populations in which rumen bacteria are found

A

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

38
Q

Cellulolytic bacteria

A

Produce extracellular cellulase, abundant in hay diets

39
Q

Hemicellulolytic bacteria

A

Use hemicellulose

40
Q

Amylolytic bacteria

A

Predominate with grain diets, significant proteolytic activity

41
Q

Proteolytic bacteria

A

Utilize amino acids as primary energy source

42
Q

Sugar utilizing bacteria

A

Use mono and disaccharides

43
Q

Acid utilizing bacteria

A

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

44
Q

Methane producing bacteria

A

Also known as archea

45
Q

Cellulolytic bacteria: growth requirements and fermentation end products

A

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

46
Q

Amylolytic bacteria: growth requirements and fermentation products

A

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

47
Q

What are the two families of protozoa in adult ruminants

A

Holotrichs and oligotrichs

48
Q

Holotrichs

A

Ovid organisms covered with cilia, store sugars until they burst

49
Q

Oligotrichs

A

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

50
Q

What is the interaction between protozoa and methanogens in the rumen

A

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

51
Q

Protozoa do not…

A

Easily pass from the rumen

52
Q

Fermentation end products of holotrichs

A

Acetic acid, butyric acid, lactic acid and H2

53
Q

Fermentation end products of oligotrichs

A

CO2, H2, acetic acid and butyric acid

54
Q

Protozoa ingest…

A

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

55
Q

What are two phases of the fungi in the rumen

A

Motile phase (zoospore) and vegetative phase (sporangium)

56
Q

Under normal conditions, the rumen fungi colonize…

A

Highly lignified fibrous material

57
Q

What is the primary protein supply for ruminans

A

Microbial protein

58
Q

How much of the animals energy needs are provided by VFAs

A

greater than 70%

59
Q

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

A

Acetic acid

60
Q

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

A

Propionic acid

61
Q

VFAs are absorbed across…

A

The forestomach walls

62
Q

VFA absorption is higher when…

A

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

63
Q

What is the venous drainage of the rumen

A

The hepatic portal vein, which goes into the liver

64
Q

Lactic acid is produced during…

A

The degradation of starch

65
Q

Unmetabolized lactic acid will cause…

A

Metabolic acidosis

66
Q

How are the rumen gases removed

A

Eructation and respiration

67
Q

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

A

60%

68
Q

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

A

More

69
Q

Lactic acid is produced by…

A

Amylolytic bacteria

70
Q

How does decreased rumen pH cause ruminal acidosis

A

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

71
Q

What can cause ruminal acidosis

A

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

Animal Nutrition & Metabolism (4 decks)

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