Forestomach Motility Flashcards
describe the optimal environment for microbial fermentation?
continuous substrate supply
appropriate temperature, space, pH control
removal of indigestible waste, microbes, VFA
what is selective retention facilitated by?
specific forestomach morphology
motility patterns
are there any glands directly into rumen?
ONLY salivary glands
which parts of the rumen stomach are on the L side?
which parts of the rumen stomach are on the R side?
list the 3 motility patterns of rumen and reticulum
mixing
eructation
rumination
describe the mixing motility pattern
PRiMARY mix pattern
reticulo-rumen contraction
list the sequence of events of a single reticulo-rumen contraction cycle
- initiation of cycle by double reticular contraction (1st - mixing, 2nd - evacuate dense material through ROO)
- contract cranial pillar aka reticulorumen fold and reticulum moves material into D sac
- D sac contracts followed by V sac
- V sac contracts and cranial pillar relaxes which moves dense material into reticulum
describe the path of a single food bolus
- initial chew and some mechanical breakdown/mix of saliva
- ingesta arrives in reticulum and is transported by mixing contraction into rumen
- V-caudal sac spills material with smallest particles into cranial-V sac and further to reticulum
- reticulum contract at beginning of primary cycles forces material in omasum through relaxed ROO
- 1-3 cycles per min
describe eructation process
GAS REMOVAL, SECONDARY motility pattern
1. cranial pillar remains solid and retains solid digesta in rumen
2. D sac contracts and moves gas cap forward
3. reticulum and cranial sac relax. displaced gas cap forces fluid and digesa in reticular region
4. exposed cardia opens and gas moves to esophagus
5. V sac contract and cranial pillar relaxes…dense material moves to cranial sac
what are the four components of rumination?
regurgitation
mastication
salivation
deglutition
when does rumination occur?
when animal rests between feeding
how is rumen content organized (top to bottom)?
TOP - gas cap
unfermented and digestable material floats
liquid layer
fully fermented material aka sediment
different rumen layers in rumen content are generated by different material ___ and bacterial ___.
density and bacterial activity
sediment layer has ___ density
high
why do ruminants always rest in sternal recumbency?
need gravity for floatation and sedimentation for rumen digesta
what is bloat?
indigestion marked by excessive accumulation of gas in rumen
failure to clear cardia due to foaming ingesta
prevents gas material removal
sediment is ___ from the rumen during the mixing movement
removed
only ___ particles leave the rumen
small
what determines particle size and its reduction rate?
digestibility, microbial action, mastication, and physical properties of ingesta
poorly digestible feed has a ___ transit time and is associated with ___ intake
longer
less
does grinding of poorly digestible fiber increase the DM intake? explain
YES, temporarily
but….
activity of acid producing bacteria increases, causing lowered pH, which provides advantage to lactate producing bacteria and disadvantage to CELLULOLYTIC, HEMICELULOLYTIC, PECTINOLYTIC species
smaller particle size requires LESS mastication, so less saliva
water influx to rumen determines ___.
dilution rate
describe how saliva production depends on chewing time and feed type
more roughage -> more mastication -> more saliva
highly digestible feed -> less mastication -> less saliva
how does a higher dilution rate effect microbe removal?
more rapid removal of microbes
how can higher dilution rate stim microbial growth?
if sufficient substrate is available
is there a sequence of cephalic, gastric, and intestinal phase of secretion in ruminants?
NOPE
since digesta flows continuously from rumen to abomasum, which linked with continuous secretion from stomach and pancreas
how is motility controlled?
VAGAL STIM
afferent signals communicate info about distension, ingesta consistency, pH, VFA concentration, ionic strength
describe how stretch receptors control motility?
located in wall/pillars
moderate distension causes increased motility
describe how tension receptors control motility?
measures tension force generated by rumen wall muscles
large rumen mat provides different resistance than mostly fluid/sluggish rumen content
describe how chemoreceptors control motility?
rumen pH 5.5-6.8 NORMAL
pH decrease in rumen causes reduced motility, helps slow down fermentation until enough material is removed from rumen
what abomasum pH stim rumen motility? why?
pH < 2-3
advances waste and fluid to omasum
signals that more food can be digested in abomasum
describe hoflund syndrome
damage to vagal innervation removes or causes erratic motility patterns
causes death
describe reticuloperitonitis
aka hardware disease
sharp object trapped in reticulum mucosa
contractions cause object to penetrate reticulum wall, cause leakage of ingesta/bacteria, which contaminates peritoneal cavity
