Forestomach Fermentative Digestion I Flashcards
define fermentation
metabolic process performed by microorganisms that convert CHO to acids, gas, and/or ethanol
what 3 things does fermentation need?
substrate
time
space
what are three substrates for fermentation?
CHO
protein
fat
what is crude protein (CP)?
critical nutrient
made of proteins and NPN (urea)
NPN compounds supply N to the rumen microbes to help build…
microbial protein
adding fat in a corn silage based diet has ___ effects on milk production and rumen fermentation
negative
fermentation is ___ than glandular digestion
mostly slower
why does fermentation require large fermentation chambers?
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
compare the end products of glandular digestion and fermentative digestion
glandular (L) and fermentative (R)
what are rumen microbes?
mutualists, coexist with host
initiate degradation of cellulose, detoxify allelochemicals, soften substrates
give an example of a microbial waste product that is used by the host
short chain FA
what’s “eaten” by the host to provide microbial protein?
microbes
what are the three general microbe types in rumen and hindgut?
bacteria
fungi
protozoa
what do bacteria microbes do?
fiber fermentation and enzymatic breakdown of CHO
substrate specific
are bacteria anaerob or facultative anaerob?
both
what do fungi microbes do?
cellulase activity
what do protozoa microbes do?
ferment fiber
ingest/feed on bacteria
slow down digestion of rapidly fermenting ingesta by ingesting/storing substrate
are protozoa anaerob?
YES
ciliates
microbes produce ___
VFA aka short chain FA
what are VFA’s?
endproduct of anaerobic microbial metabolism
how does VFA affect rumen pH, and how is that managed?
lowers pH
saliva buffer (bicarb) and removal from chamber helps maintain pH and avoid acidosis
which important vitamin does microbes produce?
vitamin B12
vitamin B12 is used for ___ synthesis
nucleic acid
also cell growth and maturation
dietary B12/Cbl is bound to…
two proteins
R protein and Intrinsic Factor forming complexes
R protein is secreted by…
saliva, gastric cells, pancreas
Intrinsic factor is secreted by…
parietal cells
where are R proteins digested to release B12? what complex is formed due to this release?
duodenum
IF-Cbl complexes
where is the IF-Cbl complex recognized for the Cbl/B12 to be absorbed?
ileum
where is Cbl/B12 stored?
liver and muscle
lasts few weeks
deficiency of ___ causes reduced microbial production and therefore B12 deficiency
cobalt (via diet)
equation for microbial yield
MY = mass of microbial DM / mass of substrate
what affects microbial yield?
temperature
pH
dilution rate of rumen fluid
C/N ratio
what is the C/N ratio?
CHO:protein
lack of ___ would cause a C/N shift
cellulose, with change in protein
what does an increased C/N mean?
ample energy but insufficient N
available energy is used by microbes for maintenance, NOT growth
what does a decreased C/N mean?
ample N for growth, but insufficient energy for maintenance
available energy used by microbes for maintenance NOT growth
increased/decreased C/N will ___ microbial yield
lower
a matched C/N will ___ microbial yield
maximize
what is urea?
important source of NPN
formed in liver
excreted in urine
stems from - deamination of endogenous aa, and N absorbed as ammonium in rumen
N flow to and from the rumen depends on…
ammonia concentration
high nutritional protein causes ___ blood urea
high
so urea secreted in urine
low nutritional protein causes ___ rumen ammonia
low
stim N flow to rumen
does urea have energy, minerals, or vitamins?
no
what happens to microbial growth in a closed system?
microbial growth declines
since nutrients exhaust and conditions become unfavorable
the rumen is an ___ system because…
OPEN
feed input, gas release/VFA absorbed, movement of content into omasum
what is an open system?
constant supply of material, growth is continuous
