Forestomach Fermentative Digestion II Flashcards

1
Q

define browser

A

animal that eats mainly browse
selectively feeds on highly digestible material
can NOT live on grass as efficiently as grazers

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2
Q

define grazer

A

animal that eats mainly grass

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3
Q

browsers eat plant material with ___ tannin

A

higher

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4
Q

which gland produces tannin neutralizer?

A

parotid gland
produces proline rich proteins

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5
Q

who has a larger parotid gland, browsers or grazers?

A

browsers

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6
Q

is rumen content of browsers layered?

A

NOPE

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7
Q

do browsers or grazers have a more homogenous rumen?

A
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8
Q

browser rumens have ___ viscosity fluid. describe the separation

A

high
separation due to floatation/sedimentation less possible, gas bubble evenly distributed

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9
Q

grazer rumens have ___ viscosity fluid. describe the separation

A

LOW
separation due to floatation/sedimentation and clear separation of gas layer

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10
Q

what stim rumen papilla growth?

A

VFA

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11
Q

VFA concentration is highest where ___ is highest

A

microbial activity

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12
Q

which of the rumen compartments does VFA absorption occur in browser?

A
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13
Q

which of the rumen compartments does VFA absorption occur in grazer?

A
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14
Q

VFA absorption rapidly removes ___ from rumen fluid

A

acid and ion

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15
Q

define mean retention time

A

time that a liquid or food particle spends in rumen
grazer > browser

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16
Q

does a long MRT restrict feed intake?

A

YES since intake of roughage is limited mostly by capacity of forestomach

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17
Q

describe the graph…how retention time differs between grazer and browser

A
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18
Q

why is particle throughput larger in browsers?

A

they rely more on plant cell content (CHO, protein)
cell content easily fermentable
fiber has small role

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19
Q

why is fluid throughput higher in grazers?

A

food particles remain longer in grazer rumen
1. removes waste and make room for new material
2. remove microbes

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20
Q

removing waste and microbe stim ___ growth, causing ___ microbial yield from forestomach

A

bacterial
increase yield

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21
Q

what is quorum sensing?

A

mechanism of bacteria regulates population density via autoinducer signal molecules

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22
Q

autoinducers ___ in concentration as function of cell density

A

increases

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23
Q

omasum functions

A

water absorption (prepares for acidic abomasum)
ingesta transport

24
Q

is omasum larger in browser or grazer?

A

grazer
since larger water absorption capacity

25
why does more water flow through the grazer forestomach?
helps remove waste and microbial protein and facilitates better fiber fermentation
26
what are the main end products of microbial VFA pathway?
27
what form are VFA's absorbed as?
protonated or dissociated
28
which exchanger is used at pH 6.8 for VFA intracell transport
VFA/bicarb exchanger
29
at what pH are each of the following circles exchangers used?
TOP - pH 6.8 BOTTOM - lower pH
30
which VFA is used for gluconeogenesis?
propionate
31
what does acetate enter the krebs cycle as?
acetyl CoA
32
what is the most important gluconeogenic substrate?
propionate MAJOR glc source
33
what two main factors help regulate pH and avoid rumen acidification?
buffer removing VFA
34
VFA accumulation in rumen ___ pH
lowers
35
how does pH affect microbial growth rate?
decreased pH < 6 causes microbes to produce lactic acid
36
rumen acidosis is due to a ___ overload
CHO
37
what are symptoms of rumen acidosis?
unspecific variable appetite, drop in milk production, D, bloat, reduced motility, increased HR, laminitis
38
lysozymes function
breaks hydrolytic glycosidic bonds of mucopolysaccharides
39
abomasal lysozymes help make use of ___
microbial proteins
40
lysozymes catalyze ___ of bacterial cell walls
hydrolysis
41
where do ruminants secrete largest amount of lysozymes?
lumen of abomasum
42
lysozymes are most active at ___ pH
low
43
can lysozymes be cleaved by pepsin?
nope
44
what percent of CP in fresh grass is true protein?
80% rest is NPN
45
what affects proportion of crude protein?
fermentation
46
describe downgrading of high biological value protein
rumen degradable protein is forst catabolized by microorganisms and then used to resynthesze bacterial protein
47
describe upgrading of low biological value protein
bacteria are able to use NPN to produce microbial protein
48
what's the most important NPN?
urea
49
how is urea recycled?
via saliva into rumen for usage by bacteria to turn to microbial protein
50
which transporters are used for urea recycling in ruminants?
AQP and urea transport (B)
51
what determines the amount of microbial protein that reaches SI?
amount of dietary CP and metabolic demand
52
what determines plasma urea in ruminant?
amount of microbial protein that reaches SI and the presence of excess ammonia in rumen
53
how is pH affected during urea toxicity?
accumulation of rumen ammonia -> rumen pH > 7.5 -> alkaline indigestion
54
describe the 3 development phases of the ruminant foregut system
55
what's rumen drinker?
fast drinking with little or no suckling causes spill over into rumen since esophageal groove gets overwhelmed or is not properly formed