L27: Forestomach motility Flashcards
what is considered normal rumen motility
- continuous mixing of bacteria and feed constituents
- retention of ingesta for microbial digestion in order to down size particles
- removal of fermentation gases, plant material and microbial yield
forestomachs are lined w/ what type of epithelium
stratified squamous
are there any glands that drain directly into the rumen
only salivary glands
what increases SA in the rumen
- honeycomb like folds in the reticulum
- rumen papillae
- omasal laminae
what can be absorbed in the rumen & omasum
VFA, electrolytes, water
what are the 3 motility patterns of the reticulum and rumen
- Mixing
- Eructation
- Rumination
eructation
removal of fermentation gases
what is the double reticular contraction that initiates mixing
1st contraction = mixing
2nd = contraction evacuates dense particles through reticulo-omasal orifice
what are the 4 components of rumination
- regurgitation
- mastication
- salivation
- deglutition
what happens during regurgitation
- LES/cardia relaxes
- inspiratory excursion of thorax
- glottis remains closed
- reversed esophageal peristalsis
when does rumination take place
between feedings when animal rests
what triggers saliva production
rumination
what is the reason for the different layers of rumen content
caused by different material density and different layers have different bacterial activity
why are ruminants always resting in sternal recombancy
they need gravity for floatation and sedementation of rumen digesta
when is sediment removed from the rumen
during the mixing movement
what determines particle size and reduction rate
- digestibility
- microbial action
- mastication
- physical properties of the ingesta
since the rumen volume is limited, the intake rate cannot exceed the ingesta ________ rate
outflow
water influx to the rumen determines ______ rate
dilution
what results in the production of more saliva vs less saliva
more saliva: more roughage food, more mastication
less saliva: highly digestible feed, less mastication
what would a higher dilution rate result in
a more rapid removal of microbes
under what conditions can a higher dilution rate stimulate microbial growth
if there is sufficient substrate; it increases the yield for microbes w/ faster replication rates
how can dilution rate both positively & negatively affect VFA production and microbial yield
positively: higher dilution rate sitmulates microbial growth when there is sufficient substrate
negatively: VFA producing bacteria could be reduced as a result of the rapid passage of fluid
what is considered a favorable environment for optimal microbial fermentation?
- continuous substrate supply
- appropriate & constant temperature
- sufficient time and space
- pH control
- removal of indigestible wastes, microbes and VFAs
when are primary and secondary motility patterns occuring?
all the time; continuously
in the rumen, unfermented & digestible material will _____ ; fully fermented material will ______
float
sink
what separates the sediment at the bottom of the rumen from the floating fiber mat
liquid layer
why is fluid and gravity crucial for proper stomach functioning
flotation & sedimentation only work in a fluid medium and under the influence of gravity
poorly digestible feeds have _____ transit time and are associated with _______ dry matter intake
longer
less
would grinding of poorly digestible fiber increase dry matter intake?
only initially
- then the activity of acid producing bacteria will increase, lowering pH
- low pH gives lactate producing bacteria an advantage while hindering cellulolytic, hemicelulolytic, pectinolytic species
- smaller particles require less chewing, less chewing = less saliva
why could rapid passage of feed (poorly digestible) cause decreased VFA production
rapid passage causes a lower pH
lower pH hinders cellulolytic, hemicelulolytic and pectinolytic species
how is motility controlled
vagal innervation of the rumen
- afferent signals communicate info about distension, ingesta consistency, pH, [VFA] & ionic strength
- stretch, tension & chemoreceptors
normal pH of rumen
5.5-6.8
what occurs when the abomasum has a drop in pH below 2-3
rumen motility is stimulated to advance waste & fluid to the omasum
Hoflund syndrome
* damage to vagal innervation removes or causes erratic motility patterns
* usually results in death
Reticuloperitonitis
hardware disease - sharp object get stuck in the reticulum
contractions cause object to penetrate reticulum wall, causing leakage of ingesta and bacteria into the peritoneal cavity
