Rumen Flashcards
Need for rumen motility (7)
- Indicator of health status
- inoculates ingesta
- mixes saliva and ingesta to buffer
- elimination of gas (secondary contr)
- prevent accumulation of VFAs locally (acidosis)
- help VFA absorption through wall
- prevent impaction
Controls of rumen motility (6)
- Intrinsic
- Extrinsic
- Other innervation
- Gastric center Regulation
- Tension receptors
- Epithelial receptors
Intrinsic control (3)
no pacemakers
smooth muscle tone changes a little bit from poor Cajals
may excite triggers for extrinsic
Extrinsic control (3)
vagus (cranial 10), multiple branches
responsible for primary and secondary
controlled by bilateral gastric centers of medulla (frequ, duration, amplitude)
Splanchnic innervation (2)
motor nerves that provide sympathetic inn.
inhibitory
Gastric Center Stimulation (3)
Buccal mechanoreceptors (eating and chewing)
tension receptors
epithelial rec.
Gastric center inhiition (5)
- high tension in ret and rumen
- tension rec
- epithelial recep.
- Pain (anywhere but mainly in guts)
- Drugs (xylazine, alpha 2 agonists)
Tension receptors
stimulatory: low/moderate distension
inhibitory: high distension (different theories)
Epithelial receptors Mechanical
Stimulate: a light touch will trigger the gastric center (unchewed fiber in the raft)
Inhibit: severe distension
Epithelial receptors Chemical
stimulate: acid in ABOMASUM (empty) will go to gastric center
inhibit: acid in the RUMEN
Primary contraction sequence (3) - mixing
double contraction of retic-rumen
contraction of dorsal sac (Cr –> cau)
contraction of ventral sac (ca –> cr)
Primary contraction frequ
eating 35-45
resting 60-90
ruminating 45-60
More with more forage
Secondary cycle sequence (3) - eructating
contraction of caudo-ventral blind sac caudodorsal sac (caudal to dorsal) ventral sac (caudal to dorsal)
Reasoning for secondary contraction (5)
microbes make CO2
Builds up on rumen roof
secondary contraction moves air to cardia region
gas over cardia causes reflex opening
animal inhales, drawing air into esophagus
Implications of secondary (2)
some gas is inhaled and can put ktones in blood and milk.
flroth will not eructate
Sequence of events for Rumination (6)
retic contracts just before primary negative pressure from closed glottis (lift tongue and soft palate) cardia and LES relax Esophagus does reverse peristalsis raises tongue to push out water chew for 10-60sec
Outcome of rumination (2)
bucca receptor stim - more salivation and mixing
smaller particle size - high Sur area and chance of passing to omasum
Atony or stasisq
no motility
hypomotility
less motility
Potential weak points in mechanisms of decreased motility (4)
depression of Gcenter
less stim
more inhibit
no neuromusculare transmission (from 2 nerve junctions)
Conditions causing decreased motility (10)
Not eating, DA, Hardware (TRP), Bloat, Impaction, rumenal acidosis, Milk fever, Vagal indigest, Pain/stress, Drugs
Mechanism of… Not eating
Less stimulat of gastric center (less bucco stim, less RR tension rec stim, less epithel recep stim so less rumin.
Pain
Mechanism of… DA
Left more common
stim abomasal tension recep which inhibits gstric center
Mechanism of… Hardware (TRP)
depression of Gastric center from Pain and inflammation/fever. Then inappetance
Mechanism of…bloat
Free gas - no secondary cycle. increase inhibitory signals from epithelial receptors and high-threshold tension recep.
Frothy - no open gas for cardia. increase inhibitory from epithelial recep and high-thresh tension rec
Mechanism of… impaction
a lot of poor feed
high rumen pressure and the usual (epithelial and tension)
Mechanism of…ruminal acidosis
increases inhibitory signals from epithel chemoreceptors
may lead to bloat
Reasons (3) - high grain, change bacteria, more lactic acid
Mechanism of… Milk fever
Calcium is needed for release of ACH at NMJ and i the Ca/Calmodulin complex for smooth muscle
Mechanism of…vagal indigestion
vagotomy stops motility, rumination and eructation
inflamm/adhesions around vagus
OR.. adhesions decrease separation from reticulum and decrease outflow
Mechanism of…stress/fear
increase symp (splanchnic, decreases catechol), increase inhibitory effect on gastric ce?
Mechanism of…drugs (inhibitory)
Atropinen- ACH antagonist, blocks parasymp transmission
Sedatives - depress gastric center
Drugs that increase motility
Neostigmine (increase parasymp.) , Metoclopramide
perrisodactyl
odd toed
artiodactyl
even toed
4 types of herbivore fermentation
- pre-gastric
- Small intestine (not efficient)
- Cecum
- Colon
Animals with post-gastric (hindgut - colon and cecum)
Horses, Rhinos, elephants, pigs (mostly colon)
Rodents, Rabbits (mostly cecum)
Animals with Small intestinal fermentation
bear
Pre-gastric (transition group)
has non-secretory part in enlarged stomach
Hippo, Sloth, Kangaroo, beaver
Pseudo-ruminants
Camelids
no Omasum but ruminates
True ruminants
4 stomachs
cervids, bovines, giraffes
Types of Pre-gastric fermentation (3)
- Transition (outpouching)
- pseudo-rum. (3 stomach)
- Ruminants
Benefits of rumination (4)
B vitamins absorbed
bact protein
detox plants
use colon for water
problems with ruminant (3)
slow passage
limited capacity
poor feed passes slowly
3 types of ruminants
- browsers (deer, giraffe)
- grazers (sheep, cattle)
- intermediates (goat)
possible reasons for differences in browsers and grazers
- browsers choose concentrate(more DE)
2. browsers must eat concentrate (not big enough rumen for raft)
Low feeds cause ______ retention times and thus _____
long, larger rumen. So browsers will be bigger.
Browser, grazer trade-off (from grazer perspect.)
less time eating (less predation)
less absorptive capacity
longer retention time
decrease buoyancy of raft by…
removing gas in forage (less dense will float)
Factors affecting rumen pH
Diet (more conc. lower pH)
Level of feed intake (more frequent, higher pH CHANGES)
time after feeding
Processing (more = less pH)
Rumination time affects pH how?
lower rum time, lower salivation, lower pH
Cascade of diet on rumen pH
more grain, more rapid VFA prod, also more strep bovis, more lactic acid, less megas Elsd. living
more forage, more saliva and more rumination
Cascade of level of feed intake
from maintenance to full feed gives more substrate for fermentation, lower pH
Time after feeding problems
starvation, rumen pH increases
3-4 hours after feeding, pH goes low
More frequency, less fluctuation
osmolality increases due to increased fermentation, water flows in.
Cascade of processing of feed
smaller particles, less chewing, less saliva (and less motility), increases SA and fermentation rate
Problems with wrong pH (2)
- Motilty (epithelial recep, see acid and inhibit)
2. microbes
Buffering capacity
Saliva (sodium bicarb)
carbonic Anhydrase
or add NaHCO3 to diet
Functions of Ssaliva (9)
mastication, taste, thirst sens, heat loss, bacteriostatics, buffer, nutrients for microbes, anti-frothing (lower surface tension), no amylase in ruminants
Amount and composition of saliva (4)
less than 10% of body weight
mucus - minors
serous - parotid
mixed - submand
As flow increases, higher bicarb levels in saliva
Another result of grain overload (5)
high concentrates, rumen becomes hypertonic, water flows into rumen, splashing sounds, systemic dehydration
osmotic pressure
normally hypotonic in rumen
max gas production is…
2-4 after eating
400 L/day (cattle), 50 for sheep
Gases produced
Co2 (65), Ch4(25), N2(7), O2, H2, H2S
Ionophores effect on gas production
H2 lower and goes to prop
Rumen turnover reasons (5)
digestibility
amount of feed (more feed = more distension = more motility = lower digestion time)
Particle size
Microbial efficiency
How is microbial efficiency done in rumen turnover (3)
favors fast growing for protein, keeps bact in expon phase, less protozoa to eat bact
Bacteria basic characteristics
mostly gram negative
anaerobes
=50% of microbial mass
10^10
bacteria locations
single cells or clumps
to the feed
to the rumen epithelium
to protozoa
Primary bacteria do….
directly ferment
secondary bacteria …
use prodcuts from primary (m. elsdensii, methanogens)
ionophores do…
More feed efficiency - more prop, less methane
prevent lactic acidosis - less s. bovis making lactate. (not effective for SARA)
prevents bloat - less s. bovis so no slime from grain
prevent ketosis - less BHB
maybe Cox treatment?
the two that make D and L lactate are…
strep bovis
lactbacillus
the two that make propionate are…
m. elsdensii (non-randomizing) selenomonas ruminanticum (randomizing)
one that makes ethanol…
R. albus (when high H tension). Then it makes Acetate
Bacteria and Protozoa
A lot more bacteria, same mass of protozoa
two types of protozoa
holotrichs and oligotrichs
ionophores kill gram _____ bacteria
positive
protozoa like
starch, (but not too much or pH will kill)
structural CHO
cellulose (slow), hemi, pectin (fast)
As NDF (all three) increases
animals consume less forage (limits DMI)
As ADF increases,
DE decreases
Progression of CHO fermentation
Sugars, starches, celluloses
Non-fiber CHO
pectins, starch, sugar
Fiber CHO
Hemi, Cellu, Lignin
How does high starch depress milk fat? (2 mainly)
more prop, more glucogenic, more lactose to be produced, more osmotic drive for water into milk to dilute fat.
acetate decreases, less Acetyl-CoA, less through ACC, less milk fat.
CLAs on milk fat
inhibits ACC. so no more LCFA for milk fat. Also increases insulin receptors and more glucose goes into mammary and dilutes milk
The bigger the VFA, the _______ they transport
faster (weird)
pH effect on absorption of VFAs.
lower the pH, becomes non-ionized, moves across without transporter, alot faster
VFAs are absorbed… (4)
rumen wall - through BL monocarboxylate transporters (slower for smaller) (11)
passively when acidic (1 and 10)
ionized VFAs go through with cations (Na/H, VFA, HCO3) (2,9,6)
CO2 diffusion
The problem with a lactic acidosis
normally poor movement (low pKa).
lower pH becomes protonated, moves quickly across membrane, then to the animal, systemic acidosis. This is D lactic so slowly dealt with
Lactate MCT is brutally slow
butyrate is about _____ % metabolized in rumen epithel. and goes to ____
90, other tissues in body for energy
What to treat for ammonia toxicity?
vinegar to convert to NH4+ so doesn’t absorb to system
5-8% acetic, 2-8 L
What kind of channels transport ammonium?
potassium
Absorption. Chloride moves ____ and sodium moves _____ via _____, potassium moves _____
against concentration gradient, against chemical and electrical, active transport, freely
VFAs produce _____ energy in rumen than digestion of starch in monogastric for ______
less, non-structural
Urea is transported into rumen from liver by…
Aquaporins and urea transporters
Recycled urea goes to
saliva (into rumen)
blood into the rumen (urease)
Bacterial protein synthesis needs three things to be in check
Ammonia
Carbon skeletons
Energy
(match the curves as well)
Consequences of not being lined up on curves
not enough protein for growth and do cell maintenance
Ruminants convert lipids from ____ to ____
PUFA (cis) to saturated
Lipids _____ palatability in ruminants
decrease (no more than 10% please)
Lipid metabolism does ______ first then ______ mainly by (85%)
Hydrolysis, hydrogenation, Butyriovibrio
Which pathway do ruminants use for lipid metabolism is…
alpha-glycerophosphate. Things all go to glycerol and the fatty acid
because of rumen bacteria, we don’t need ____
lipase
main trans fatty acid in milk
vaccenic acid
biohydrogenation is…
bacteria adding hydrogens because UFA are toxic. Also changes cis to trans to make more stable
FAs can inhibit methane by… (2)
inhibit the methanogens
PUFA are another hydrogen sink (not just methane now)
Effects of fat on the feed (5)
coats feed (less availablilty) decreases motility though CCK LCFA toxic to bacteria (high conc) consistency of feed rancid
LCFA are digested in ____ by ____
SI, bile salts, carried by chylomicrons through lymph
Ruminant body fat is ____ and monogastric is _____
saturated completely, only partly satutrated
Phases of rumen development (4)
Newborn
pre-ruminant (1-3wks)
transitional (3-8)
weaning and post
Newborn rumen is …
60% abomasum
30% rumen
not secreting acids or proteases to allow IGs across.
secreting anti-trypsin factor
IGs high in colostrum
M, A and G (G is the most)
Syndesmochorial placenta
prevents prenatal transmission of IGs. (horse, pigs, ruinants)
Maternal mucosa persists adding another layer so there is not transfer
Interesting things in colostrum
high vit A and D Lactose Cal and mag high fat Lactobacilli, E.coli, strep, chlostiridials start to colonize
Things if not enough passive transfer (3)
navel infection
joint
scours
Factors in groove closure
suckling increases salivation, saliva has esterases to begin digestion, glossopharngeal nerve (9) is stimulated by levels of Na or Cu, Eferent vagal output closes groove. (omasm is undeveloped here)
Closure is mechanically done by…
spiral lips shorten and appose
Adverse affects from drinking
lactic acidosid, Diarrhea, Bloat
suckling causes rennin and HCl secretion from abomasum and then….
a hard curd forms (butterfat), the remaining fractions leave and the curd undergoes slow digestion and release into SI
Transitional phase….
salivary glands develop
rumen develops from dry feed and begin to regurgitate
microflora and then VFA production, not glucose
microflora and protozoa begin from
direct contact with other animals
Weaning/post changes
Rennin to pepsinogen
In CHO engorgement, ______ bacteria will work faster than _______ to make D Lactate. Then the Gram ____ replace the others. Osmolality comes in and causes _________ (4)_____
Amylolytic (strep bovis), cellulolytic. Positive. Systemic dehydration with increased HR, distended rumen, diarrhea
In CHO engorgement, rumen motility decreases because…
epithelial receptors detect pH and inhibit.
lactate in duodenum will inhibit.
Stasis will allow pH to increase again
After engorgement, bacteria will change populations, osmolality will change, rumen motility will stop, and then …. (7)
lactic acid will cause systemic acidosis, increases resp rate animal becomes anuric depression lethargic potassium kicks into heart cells heart stops
