Forestomach Fermentative Digestion I

Question 1

define fermentation

Answer 1

metabolic process performed by microorganisms that convert CHO to acids, gas, and/or ethanol

Question 2

what 3 things does fermentation need?

Answer 2

substrate
time
space

Question 3

what are three substrates for fermentation?

Answer 3

CHO
protein
fat

Question 4

what is crude protein (CP)?

Answer 4

critical nutrient
made of proteins and NPN (urea)

Question 5

NPN compounds supply N to the rumen microbes to help build…

Answer 5

microbial protein

Question 6

adding fat in a corn silage based diet has ___ effects on milk production and rumen fermentation

Answer 6

negative

Question 7

fermentation is ___ than glandular digestion

Answer 7

mostly slower

Question 8

why does fermentation require large fermentation chambers?

Answer 8

allows space/storage and optimal conditions for processes such as…
pH, moisture, ion, redox potential
slow movement/long transit times for reaction
specific motility patterns
continuous removal of gas/waste

Question 9

compare the end products of glandular digestion and fermentative digestion

Answer 9

glandular (L) and fermentative (R)

Question 10

what are rumen microbes?

Answer 10

mutualists, coexist with host
initiate degradation of cellulose, detoxify allelochemicals, soften substrates

Question 11

give an example of a microbial waste product that is used by the host

Answer 11

short chain FA

Question 12

what’s “eaten” by the host to provide microbial protein?

Answer 12

microbes

Question 13

what are the three general microbe types in rumen and hindgut?

Answer 13

bacteria
fungi
protozoa

Question 14

what do bacteria microbes do?

Answer 14

fiber fermentation and enzymatic breakdown of CHO
substrate specific

Question 15

are bacteria anaerob or facultative anaerob?

Answer 15

both

Question 16

what do fungi microbes do?

Answer 16

cellulase activity

Question 17

what do protozoa microbes do?

Answer 17

ferment fiber
ingest/feed on bacteria
slow down digestion of rapidly fermenting ingesta by ingesting/storing substrate

Question 18

are protozoa anaerob?

Answer 18

YES
ciliates

Question 19

microbes produce ___

Answer 19

VFA aka short chain FA

Question 20

what are VFA’s?

Answer 20

endproduct of anaerobic microbial metabolism

Question 21

how does VFA affect rumen pH, and how is that managed?

Answer 21

lowers pH
saliva buffer (bicarb) and removal from chamber helps maintain pH and avoid acidosis

Question 22

which important vitamin does microbes produce?

Answer 22

vitamin B12

Question 23

vitamin B12 is used for ___ synthesis

Answer 23

nucleic acid
also cell growth and maturation

Question 24

dietary B12/Cbl is bound to…

Answer 24

two proteins
R protein and Intrinsic Factor forming complexes

Question 25

R protein is secreted by...

Answer 25

saliva, gastric cells, pancreas

Question 26

Intrinsic factor is secreted by...

Answer 26

parietal cells

Question 27

where are R proteins digested to release B12? what complex is formed due to this release?

Answer 27

duodenum IF-Cbl complexes

Question 28

where is the IF-Cbl complex recognized for the Cbl/B12 to be absorbed?

Answer 28

ileum

Question 29

where is Cbl/B12 stored?

Answer 29

liver and muscle lasts few weeks

Question 30

deficiency of ___ causes reduced microbial production and therefore B12 deficiency

Answer 30

cobalt (via diet)

Question 31

equation for microbial yield

Answer 31

MY = mass of microbial DM / mass of substrate

Question 32

what affects microbial yield?

Answer 32

temperature pH dilution rate of rumen fluid C/N ratio

Question 33

what is the C/N ratio?

Answer 33

CHO:protein

Question 34

lack of ___ would cause a C/N shift

Answer 34

cellulose, with change in protein

Question 35

what does an increased C/N mean?

Answer 35

ample energy but insufficient N available energy is used by microbes for maintenance, NOT growth

Question 36

what does a decreased C/N mean?

Answer 36

ample N for growth, but insufficient energy for maintenance available energy used by microbes for maintenance NOT growth

Question 37

increased/decreased C/N will ___ microbial yield

Answer 37

lower

Question 38

a matched C/N will ___ microbial yield

Answer 38

maximize

Question 39

what is urea?

Answer 39

important source of NPN formed in liver excreted in urine stems from - deamination of endogenous aa, and N absorbed as ammonium in rumen

Question 40

N flow to and from the rumen depends on...

Answer 40

ammonia concentration

Question 41

high nutritional protein causes ___ blood urea

Answer 41

high so urea secreted in urine

Question 42

low nutritional protein causes ___ rumen ammonia

Answer 42

low stim N flow to rumen

Question 43

does urea have energy, minerals, or vitamins?

Answer 43

no

Question 44

what happens to microbial growth in a closed system?

Answer 44

microbial growth declines since nutrients exhaust and conditions become unfavorable

Question 45

the rumen is an ___ system because...

Answer 45

OPEN feed input, gas release/VFA absorbed, movement of content into omasum

Question 46

what is an open system?

Answer 46

constant supply of material, growth is continuous