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Physiology III > Lecture 26: Forestomach Fermentative Digestion-1 > Flashcards

Lecture 26: Forestomach Fermentative Digestion-1 Flashcards

1
Q

What is fermentation

A

Metabolic processes performed by microorganisms that converts carbohydrates to acids, gases and/or ethanol

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2
Q

What plant component must be broken down by microbial fermentation

A

Fiber (cell wall)

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3
Q

What are the 3 carbohydrates from plants

A
  1. Fiber (cell wall)
  2. Sugar (cell content)
  3. Starch (endosperm)
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4
Q

What is crude protein composed of

A

Proteins and non-protein nitrogen sources

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5
Q

What is the role of non-protein nitrogen sources for the microbes and for host animal

A

NPN use urea, salts, ammonia, etc that can supply nitrogen to microbes and build microbial protein.

  1. Supplies the microbes
  2. Microbes are large source of protein to host animal as they get digested and sent to SI
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6
Q

Fats are added to ruminant diets as they are essential for fermentation but have negative effects on ___ and ___

A

Milk production and rumen fermentation

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7
Q

What are the 3 substrates needed for microbial fermentation

A
  1. Carbohydrates
  2. Proteins
  3. Fats
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8
Q

Which is slower glandular digestion or fermentation

A

Fermentation

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9
Q

What are the fast fermenting carbohydrates

A

Sugars from the cell wall are easily digestible by both pancreatic enzymes and microbes

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10
Q

What carbohydrate is fermented down 2nd fastest

A

Starch from endosperm

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11
Q

What carbohydrate takes the longest to ferment and how long does it taken

A

Fiber takes around 2-3 days (60-70hrs)

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12
Q

___ movement/ ___ transit times facilitate reaction time in fermentation process

A

Slow, long

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13
Q

What are the fermentation chambers in foregut fermenters

A

Pre-stomach chambers

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14
Q

What are the fermentation chambers in hindgut fermenters

A

Colon and cecum

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15
Q

How long does glandular digestion take

A

Very fast 2-3hrs

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16
Q

How fast does fermentative digestion take

A

Variable (fast to slow) ~2-3 days

Slow due to fiber fermentation

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17
Q

How does the space in the stomach compare in glandular vs fermentative digestion

A

Stomach in glandular digestion is fairly small and fermentative chamber is large

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18
Q

What substrates are used in glandular digestion

A

Carbohydrates, proteins and fats

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19
Q

What substrates are used in fermentative digestion

A

Carbohydrates, proteins, fats, non-protein nitrogen

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20
Q

What are the end products of glandular digestion

A

Mono, di and tri peptides, monosaccharides, Micelles

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21
Q

What is the end product of fermentative digestion

A

VFA, microbial protein and gases

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22
Q

Describe the microbial ecosystem in the GI track of cattle

A
  1. Cattle consume feed
  2. Rumen microbes break down feed
  3. Microbes grow
  4. Microbes produce byproducts including energy as VFA and protein
  5. Regulate rumen environment
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23
Q

What do microbes produce as byproducts

A
  1. VFA
  2. Proteins
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24
Q

Microbes initiate degradation of ___, ___ allele chemicals and soften certain substrates

A

Cellulose, detoxify

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25
Microbial waste products are ___ used by mammalian host
short chain fatty acids
26
The microbes are ___ by mammalian host and provide microbial protein
Eaten
27
What is the largest proportion of microbe in rumen and hindgut
Bacteria
28
What do bacteria do in rumen and hindgut
Fiber fermentation and enzymatic break down of carbohydrates
29
What do fungi do in rumen and hindgut
Cellulose activity
30
What do Protozoa do in rumen and hindgut
1. Ferment fiber 2. Ingest bacteria (regulate growth) 3. Slow digestion of rapidly fermenting starch by ingesting/storing
31
What microbe in rumen and hindgut regulates bacterial growth
Protozoa
32
___are the end product of anaerobic microbial metabolism
VFA’s
33
What do VFA’s do to pH and how does the body respond
Lower pH, but is buffered by saliva which has bicarbonate in it
34
What breaks down pyruvate to acetate and butyrate
Acetyl-CoA
35
Pyruvate break down results in production of __
VFA
36
What breaks down pyruvate to propionate
Lactate and succinate
37
What breaks down pentoses to acetate
Acetylphosphate
38
Microbes are ___specific
Substrate
39
What microbe species are involved in fermentation breakdown to VFA’s
Cellulolytic, hemicelulolytic, pectinolytic
40
What microbe species break down organic polymers (cellulose, starch, hemicelluose) to soluble sugars
Amylolytic species
41
What microbe species produce methane in fermentation process
Methane producing species
42
What microbe species produce acetate in fermentation process
Acids utilizing species
43
What is VitB12 essential for
Cell growth and maturation, brain development, blood synthesis and epithelial repair in GI tract
44
What is another name for vitamin b12
Dietary Cbl
45
How is vitamin b12/dietary Cbl transported normally
1. Dietary Cbl bound to R proteins and intrinsic factor - R protein is secreted b saliva, gastric cells and pancreas - IF secreted by parietal cells 2. R protein is digested in duodenum and the released Cbl forms more IF-Cbl complexes 3. In ileum the IF-Cbl complex is recognized and the Cbl is absorbed by endocytosis
46
What secretes R protein
Saliva, gastric cells and pancreas
47
What secretes IF
Parietal cells
48
How is B12 supplied to animal
Diet and/or microbial production
49
Where is Cbl stored and for how long
Liver and muscle store Cbl for a few weeks
50
What can cause damage to the supply of B12
1. Insufficient dietary 2. Insufficient transport proteins (R and F) 3. Reduced microbial production due to cobalt deficiency in diet of ruminant **microbes produce B12
51
What can cause a reduction in R protein or IF production therefore resulting in B12 deficiency
Inflammation in stomach or SI
52
Ruminant microbes can produce B12 but must be supplemented for __
Cobalt
53
What is the equation for microbial yield
Mass of microbial dry matter/mass of substrate needed
54
A high microbial yield provides an important ___source for ruminant
Protein
55
Yield is affected by __, ___, ___ and __
1. Temperature 2. PH 3. Dilution rate of rumen fluid 4. C/N ratio in diet
56
What is dilution rate in microbial yield
Large saliva volumes stabilize pH and provide fluid for dilution
57
__protein is a major source of protein for the host
Microbial
58
What is the C/N ratio of feed for livestock
Carbon to nitrogen ratio of mass of carbon to mass of nitrogen
59
The is the C/N of vascular plants
>20
60
Carbon to nitrogen ratios are an indicator for ___
Nitrogen limitation of rumen microorganisms
61
How does an increase C/N ratio affect microbial growth rate
Ample energy but insufficient nitrogen so the available energy is used by microbes for maintenance rather than growth
62
What does a decreased C/N ratio do to microbial growth rate
Ample N to support growth, but insufficient energy for maintenance, therefore available energy is used by microbes for maintenance rather than growth
63
Increased or decrease glucose/protein ratios will ___ the microbial yield
Lower
64
A matched glucose/protein ratio will ____microbial yield
Maximize
65
Where is urea formed
Liver
66
How is hepatic urea formed
Deamination of endogenous amino acids as well as from nitrogen absorbed as ammonium
67
Where is urea transported to
Liver
68
Urea is mostly excreted in urine but in ruminant urea can be ___ and returned to rumen via ___
Recycled, saliva
69
Urea adds to the ___source
Non-protein nitrogen source
70
Nitrogen flow to and from the rumen depends on ___
Rumen ammonia concentration
71
What happens to urea if there is high nutritional protein concentration
Causes high blood urea and much of it will be secreted in the urine
72
What happens to urea if there is low nutritional protein with high carbohydrate availability
Leads to low rumen ammonia availability and this will stimulate nitrogen flow to rumen
73
What stimulates nitrogen flow to the rumen
Low rumen ammonia
74
The nitrogen portion of urea is used as building block for production of ___ by ___
Protein by rumen microbes
75
What byproduct is released from urea
Ammonia
76
What are the two pathways for ammonia after released from urea
1. Produce microbial proteins 2. Liver where it is detoxified and excreted in urea
77
What can result from excess urea in diet
Overwhelm liver and toxicity can occur
78
Describe a closed system of microbial growth with lag, log, stationary and decline phase
1. Lag: adjustment period after cells are initially cultured, nothing happens 2. Log/exponential: cells start dividing and increase # 3. Stationary 4. Decline
79
Why does microbial growth decline in a closed system
Because nutrients exhaust and conditions (pH and oxygen) become unfavorable due to inability to remove waste
80
Is the rumen an open or closed system
Open
81
What does the rumens open system promote
Continuous growth of microbes maintaining cell population in log/exponential phase
82
Why/how is the rumen an open system
1. Continuous feed input 2. Gas released, VFA absorbed, buffers 3. Movement of rumen contents (microbes, undigestible material, VFA microbial waste) into omasum
83
What are some ways in which the rumens open system can be damaged and cause it to enter stationary and eventually death phase
1. Diet inappropriate 2. Can’t get rid of waste 3. Lack of buffers released in saliva, acidic

Physiology III (34 decks)

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