Forestomach Fermentative Digestion II Flashcards
define browser
animal that eats mainly browse
selectively feeds on highly digestible material
can NOT live on grass as efficiently as grazers
define grazer
animal that eats mainly grass
browsers eat plant material with ___ tannin
higher
which gland produces tannin neutralizer?
parotid gland
produces proline rich proteins
who has a larger parotid gland, browsers or grazers?
browsers
is rumen content of browsers layered?
NOPE
do browsers or grazers have a more homogenous rumen?
browser rumens have ___ viscosity fluid. describe the separation
high
separation due to floatation/sedimentation less possible, gas bubble evenly distributed
grazer rumens have ___ viscosity fluid. describe the separation
LOW
separation due to floatation/sedimentation and clear separation of gas layer
what stim rumen papilla growth?
VFA
VFA concentration is highest where ___ is highest
microbial activity
which of the rumen compartments does VFA absorption occur in browser?
which of the rumen compartments does VFA absorption occur in grazer?
VFA absorption rapidly removes ___ from rumen fluid
acid and ion
define mean retention time
time that a liquid or food particle spends in rumen
grazer > browser
does a long MRT restrict feed intake?
YES since intake of roughage is limited mostly by capacity of forestomach
describe the graph…how retention time differs between grazer and browser
why is particle throughput larger in browsers?
they rely more on plant cell content (CHO, protein)
cell content easily fermentable
fiber has small role
why is fluid throughput higher in grazers?
food particles remain longer in grazer rumen
1. removes waste and make room for new material
2. remove microbes
removing waste and microbe stim ___ growth, causing ___ microbial yield from forestomach
bacterial
increase yield
what is quorum sensing?
mechanism of bacteria regulates population density via autoinducer signal molecules
autoinducers ___ in concentration as function of cell density
increases
omasum functions
water absorption (prepares for acidic abomasum)
ingesta transport
is omasum larger in browser or grazer?
grazer
since larger water absorption capacity
why does more water flow through the grazer forestomach?
helps remove waste and microbial protein and facilitates better fiber fermentation
what are the main end products of microbial VFA pathway?
what form are VFA’s absorbed as?
protonated or dissociated
which exchanger is used at pH 6.8 for VFA intracell transport
VFA/bicarb exchanger
at what pH are each of the following circles exchangers used?
TOP - pH 6.8
BOTTOM - lower pH
which VFA is used for gluconeogenesis?
propionate
what does acetate enter the krebs cycle as?
acetyl CoA
what is the most important gluconeogenic substrate?
propionate
MAJOR glc source
what two main factors help regulate pH and avoid rumen acidification?
buffer
removing VFA
VFA accumulation in rumen ___ pH
lowers
how does pH affect microbial growth rate?
decreased pH < 6 causes microbes to produce lactic acid
rumen acidosis is due to a ___ overload
CHO
what are symptoms of rumen acidosis?
unspecific
variable appetite, drop in milk production, D, bloat, reduced motility, increased HR, laminitis
lysozymes function
breaks hydrolytic glycosidic bonds of mucopolysaccharides
abomasal lysozymes help make use of ___
microbial proteins
lysozymes catalyze ___ of bacterial cell walls
hydrolysis
where do ruminants secrete largest amount of lysozymes?
lumen of abomasum
lysozymes are most active at ___ pH
low
can lysozymes be cleaved by pepsin?
nope
what percent of CP in fresh grass is true protein?
80%
rest is NPN
what affects proportion of crude protein?
fermentation
describe downgrading of high biological value protein
rumen degradable protein is forst catabolized by microorganisms and then used to resynthesze bacterial protein
describe upgrading of low biological value protein
bacteria are able to use NPN to produce microbial protein
what’s the most important NPN?
urea
how is urea recycled?
via saliva into rumen for usage by bacteria to turn to microbial protein
which transporters are used for urea recycling in ruminants?
AQP and urea transport (B)
what determines the amount of microbial protein that reaches SI?
amount of dietary CP and metabolic demand
what determines plasma urea in ruminant?
amount of microbial protein that reaches SI and the presence of excess ammonia in rumen
how is pH affected during urea toxicity?
accumulation of rumen ammonia -> rumen pH > 7.5 -> alkaline indigestion
describe the 3 development phases of the ruminant foregut system
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
