Ruminant GIT (Pelzer) Flashcards
Ruminants are ? fermenters
foregut (rumen, reticulum and omasum)
Why do ruminates ruminate (chew their cud)?
to break food down into smaller particles so that fermentation in rumen can take place on a larger surface area
How many gallons/liters can can cow’s stomach hold?
60 gallons // 240 liters
why don’t lambs, kids and calves ruminate?
Forestomach hasn’t fully developed yet. Also, they drink milk, so no need for fermentation yet.
Describe the flow of milk in ruminant stomach
Esophagus -> esophageal groove -> thru reticulo-omasal opening ->-> abomasum
What stimulates closure of the esophageal groove?
- anticipation of suckling
- act of suckling
- fluid containing salts (Ca2+ and Na+– signal receptors in pharynx)
What diminishes closure of esophageal groove?
- after weaning and age
- can be stimualted by antidiuretic hormone (ADH – production stimualted by hypothalmus – animal becomes dehydrated -> ADH rises -> seeks out water -> water bypasses rumen and into abomasum)
When do the rumen papillae begin to develop?
when animal begins to eat solid material and volatile acids are produced (VFAs)
What diet helps the development of rumen musculature?
Solid food – Grain diets
How are microbes, which are required for rumen fermentation, obtained?
They are obtained post-natally
1. environment (eating/putting random things into their mouths)
2. mother licking baby @ time of birth
3. presence of other ruminants (shared water, shared grazing or feeding areas)
5 functions of forestomachs
- Catch all of the feed and water consumed
- Provide a vat for fermentation to occur (keep process “warm” @ 97ºF)
- Form cud (so that food can be rechewed into smaller pieces
- Absoprtion of VFAs
- Control outflow
What forage do cows eat?
Pasture Forage
- Legumes (highest in protein; alfalfa)
- Grass (10-20% dry matter)
Processed Forage
- Hay (90% dry matter)
- Silage (fermented)
increase in plant maturity = decrease in digestibility
- grass more digestible if cut in spring (immature) versus in/after summer (mature)
- herbivores require concentrate to meet adequate vitamin/mineral needs (concetrate sources: grain/non-fortified or commercial/fortified)
Structural components of forage
- Complex CHOs: cellulose, hemicellulose and pectin
- Lignin: not a CHO and is not digestible; content increases as the plant matures + warmer temps
- Fiber = cellulose, hemicellulose, lignin
- Protein (legumes+++)
- Soluble CHOs (simple sugars)
incr. in plant maturity = decr. in digestibility (e.g. spring vs summer)
Contents of grain
- Soluble CHOs – rapid fermentation
- Protein (legumes/soybean meal > wheat/oat > barley > corn)
- little fiber
Grain overload -> grain is highly digestible = highly fermentable -> decreases the pH b/c of VFA production -> injected sclera, sloshy rumen, tachycardia and tachypnea
Role of microbes in ruminant stomach (4)
- Produce cellulase (breaks down complex CHOs into mono/oligosaccharides)
- Break sugar down into VFAs (acetate, propionate, butyrate)
- Break down soluble CHOs into VFAs
- Break down proteins into AAs and NH3
microbes produce enzymes that are required for fiber digestion
Microbes are comprised of what?
- Lots of bacteria (mostly anaerobic) that produce enzymes which break down fiber, soluble CHOs and proteins
- Fungi (yeast) for plant cell wall digestion
- Protozoa (anaerobic) to ingest bacteria, as well as starch and protein
3 associations of bacteria
- Fluid-associated
- Particle-associated
- Epithelium-associated
What provides 60-80% of energy requirements in ruminants?
Volatile Fatty Acids (VFAs)
- different from dogs/cats, humans, etc. who utilize on glucose
Ratio of VFAs on a high-fiber diet
70% acetate, 20% propionate, 10% butyrate
How is fat digested in ruminants?
- only partially fermented; get digested in SI like in monogastric species
- free fatty acids cannot be absorbed from rumen; get absorbed in SI
- rumen protected fat pass directly to SI to be absorbed
How is protein absorbed in ruminants?
Most is fermented: microbes break down protein into peptides, which then get absorbed:
- absorbed and turned into microbial protein
- absorbed and degraded into NH3 (ammonia), then into microbial protein
How is urea produced and where is it excreted in ruminants?
Produced by protein breakdown, excreted in the SALIVA (other species: excreted in urine) –> urea in saliva gets recycled and incorporated into microbial protein
How much saliva is produced in cows daily and why?
25-50 gallons/day
- saliva recycles water
- recycles NH3 via urea
- has HCO3- (a buffer)
- recycles electrolytes (K and P)
- helps when eating forages
What temperature must forestomach be for fermentation?
37ºC (98.6ºF)
Ruminal grooves move. Explain 2 effects of this movement.
Can distort shape of stomach sacs –>
1. allows for rumen in a synchornous contraction to mix ingesta
2. allows for sacs to manipulated for gas to move to cardia area so they can be eructated (burped) out
Water, small particles and non-digestible material get removed out from reticulorumen and moved to where?
Omasum then abomasum
number of reticulorumen contractions
Cycle occurs 1-3x every minute
- are under intrinsic and extrinsic nervous control (vagus nerve)
Why do contractions decrease as reticulorumen pH decreases?
low pH -> contractions decrease in order to slow down fermentation activity (the over- production of acid in rumen from fermentation is what stimulates contractions to decrease).
Primary versus Secondary reticulorumen contractions
Both remove fluid and ingesta AWAY from the cardia (carida must be clear for eructation to occur)
Primary
- biphasic for mixing ingesta & aids in separation of large & small particles
- material from reticulum and rumen then get pushed into omasum during reticular contractions
Secondary
- follows a primary contraction
- gas gets pushed toward cranial rumen, while liquid ingesta gets moved away from the cardia -> gas enters esophagus and gets eructated (burped) out
Two 1º contractions per 2º contraction –> cow burps q2-3 mins
Role of regurgitation in ruminants
- allows for re-mastication of rumen ingesta (break into smaller particles)
- food gets regurged, water gets squeezed out by tongue then swallows; then, just cud is left (what gets re-masticated)
high-fiber diets produce more cud
What absorbs VFAs?
Rumen papillae
How is free-gas bloat versus frothy bloat distinguished in ruminal tympany (“bloat”)?
pass a tube
- gas will come out; froth will be present in very end of tube when you remove
3 obstruction locations of free-gas bloat?
thoracic inlet, base of the heart, and post-pharyngeal
Why does bloat occur?
Cardia is obstructed (by water, ingesta, or foam) –> eructation (burping) cannot occur –> cyclical (1º and 2º) contractions cannot occur –> rumen fills // cow bloats
Consequence of bloat
Rumen fills up so much that it compresses the caudal vena cava –> reduced CO –> hypoxia, hypotension
Frothy bloat is caused by what diets?
- diets of lush legumes or alfalfa hay (soluble proteins)
- high concentrate/grain diets (small particle size, mucoprotein slime)
small particles in rumen = fermentation occurs faster + no cud-chewing
Mucoprotein slime produced by ruminal microbes
What causes free-gas bloat?
Uncleared cardia
- increased VFA or lowered pH due to increased concentrate which decreases rumen motility
- hypocalcemia
- blockages (obstruction of esophagus; postural bloat)
- cow in lateral recumbency (want cows to be sternal for eructation)
10-year-old heifer found greatly distended in early morning out on pasture. Grunting on expiration, evidence of fecal material all over perineal area. Rule-outs? Clinical signs/diagnosis?
Frothy or free bloat
distension of LEFT paralumbar fossa (note how high left side is compared to right side) –> everything gets pushed to the right side
- signs of colic, neck stretched out
- increased HR, hyperventilation and dyspnea, staggering
- pong resonance when percussed
- maybe down -> collapse -> death
rumen is L-shaped (L = ventral sac of rumen)
Signalment of TRP/Hardware Disease
- Dairy > beef cattle (dairy cattle feed is in close proximity/goes thru a lot more machinery, like wire-bounded hay)
- Late pregnancy or post-calving cattle (less space during contraction; pressure on diaphragm during contractions, pushing stuff forward/retic. into pericard/hepatic space)
Acute vs Chronic signs of TRP/Hardware Disease
- ACUTE: drop in milk, fever, anorexia, decr. rumen motility due to pain, stiff gait
- CHRONIC: ADR cow, fever +/-, weight loss; pericardial sac involvement (muffled heart sounds/washing machine, signs of CHF like jugular distension, brisket edema, incr. RR)
Simple Indigestion etiology
- abrupt feed changes (increase amt., change in ingredients)
- moldy feed
- frosted forages (changes sugar content)
- spoiled silage
- too much grain
Clinical signs of simple indigestion
mild and self-limiting; 1-2 days anorexia, diarrhea within 24h of anorexia (body clearing out)
Causes of Grain Overload, Lactic Acidosis, Rumen Acidosis
- excessive consumption of readily fermentable CHOs
- animals exposed to feed without adaptation (off then returned to full feed; competition @ feed bunk; recently gave birth and put back on full feed; nreak into feed room [goats])
Pathophysiology of Rumen Acidosis
- proliferation of Streptococcus bovis and production of lactate –> pH redued to ≤ 5
- bacteria and protozoa die off -> Lactobacilli take over
- Rumen osmolality increases due to increased lactate pulling water into rumen –> rumen distends w/ fluid and animal becomes dehydrated
dx: LOOK FOR ANY LIVING PROTOZOA
Effects of rumen acidosis on body
- circulatory impairment -> metablic acidosis
- decreased renal perfusion -> anuria
- gram(-) bacteria die –> endotoxic shock
- rumen fluid accumulation -> alkalotic fluid
Clinical Signs of Rumen Acidosis
depression, coma & death; atonic, sloshy, fluid-filled rumen; dehydration, increased HR and RR; staggering gait or down; diarrhea may develop the next day
“simple indigestion that went wild”
Vagal Indigestion
- definition
- types 1&2 versus types 3 & 4
Right dorsal trunk provides innervation to rumen:
Vagal indigestion: progression of rumen distension due to outflow problems
- Type 1 & 2 = failure of rumen to emtpy (omasal transport failure), or Type 3 & 4 = failure of abomasum to empty (pyloric outflow failure)
Vagus nerve controls syncronous contraction cycles, eructation/regurgitation, and closue of the gastric grovoe
Clinical signs of vagal indigestion
- distention of lower Rt. abd, distension of upper Lt. abd (“palple” form)
- decreased fecal output
- dehydration
- anorexia
- 30% have bradycardia
How to differentiate b/w normal gas in rumen versus LDA when auscultating
Gas in rumen: hear same-pitched “ping” in paralumbar fossa and over the ribs
LDA: hear a different-sounding pitch in paralumbar fossa versus over the ribs
Where do you hear a ping in RDA?
Over the ribs
Gas in Colon and rectum: underneath TPs // dorsal paralumbar area
Gas in SI: in paralumbar fossa/below it
What diets are associated with displaced abomasum?
High-grain diets and inadequate adjustments to grain (dry cow to lactating cow diet)
displaced abomasums are associated with post-partum diseases
Liptak test: abomasal versus rumen pH
Abomasum: 2-4
Rumen: 5.5-8
Clinical signs of Right-sided Torsed Abomasum (RTA)
same as displaced abomasum, but
- signs of shock, decreased refill, cool extremities
- HR 100+ bpm
- acutely ill, dehydrated
- abdominal distension
similar to GDV
Floating DA
abomasum gets filled with gas, flips to one side, clinical signs manifest, then abomasum slips back –> intermittent clinical signs
TXs for displaced abomasums
- Roll (LDA-only– put right lateral then roll to left)
- Roll and toggle
- Right flank omentopexy//Right paramedian abomasopexy
- Left flank abomasopexy
go into left paralumbar fossa -> 2 sutures in abomasum,
Prevention of displaced abomasums
-increase the effective fiber in diet (long-stem forage, hay); reduce grain
Abomasal Impaction
cattle in winter on poor-quality feed; may result from vagal indigestion, TRP, pyloric obstructions / lymphosarcoma
distended right side
Abomasal Ulcers
- high-producing dairy cows early in lactation (associated with stress)
- calves once they start eating solid feed; has been associated with copper deficiency
tx = more forage, less grain
4 zones of digesta at the bottom of the rumen
- gas cap
- fiber mat
- slurry
- liquid zone
abomasal pH versus ruminal pH
Abomasum: 5.0
Ruminal: 7.0
Signlament and and clinical signs of Hardware disease
- dairy cow
- elbows abducted
- elevated fibrinogen b/c of chronic inflammation
- “washing machine” sound = pericardial effusion
- fever
