Exam 3: Lecture 32 - Ruminant Digestive Physiology 2 Flashcards
How does the rumen look at birth?
-Rumen same size as abomasum
-No microbes
-Milk bypasses rumen via esophageal groove (don’t want milk in rumen)
-Thin wall w/ short papillae & undeveloped pillars
What happens to the rumen (& calf) by 3 weeks old?
-Calves start to ingest forage & concentrate (grain)
-Microbes start to establish - cow licks the calf, pick up microbes from environment
-Rumen enlarges ->mucosa transforms, papillae grow
What stimulates rumen papillae development?
-Grain (more than hay)
-Why grain is offered to dairy calves early
What is the anatomical structure of the newborn/young calf that connects the cardia region to the omasum?
-Esophageal groove
What is the job of the esophageal groove?
-Bypassing the forestomachs
-Important b/c milk is poorly digested in rumen
When is the esophageal groove prominent in ruminants?
-Functional in calf through weaning age
-Inactive in adult
Formation of the esophageal groove is stimulated by
-Chemical (milk)
-ADH
-Suckling
Rumen fermentation produces a lot of gas, what are they?
-65% CO2
-25% CH4
-7% N
-Trace amounts of O2, H2, and H2S
How much gas does rumen fermentation produce?
-Up to 600 L of gases/day
What is eructation stimulated by?
-Gas pressure in the rumen
What are the major gases that stimulates eructation?
-CO2 & CH4
(Gas production peaks 30 min. to 2 hours after feeding)
What forces gas into the reticulum towards the cardia during eructation?
-Secondary rumen contractions
What are the 5 F’s of abdominal distension?
-Fart (gas)
-Fluid
-Food
-Fetus
-Fat (visceral/intra-abdominal fat, subcutaneous/extra-abdominal fat)
What is important when you have a “bloated animal”?
-Important to ascertain cause of abdominal distention when examining a “bloated” animal
What is “vagal indigestion syndrome”?
-Gradual development of abdominal distention secondary to rumenoreticular distention
What causes vagal indigestion syndrome?
-Diseases resulting in injury, inflammation, or pressure on vagus nerve
How many “types” of vagal indigestion syndrome are there?
-4
What is type 1 vagal indigestion syndrome?
-Free gas bloat/failure to eructate
What is type 2 vagal indigestion syndrome?
-Failure of transport out of rumen (blockage at reticulo-omasal orifice)
What is type 3 vagal indigestion syndrome?
-Failure of transport out of abomasum (blockage - impaction or displacement)
What is type 4 vagal indigestion syndrome?
-Indigestion associated with advanced pregnancy (large fetus shifts the location of the abomasum)
What is this shape called?
-Papple shape
Explain a “papple shaped abdomen
-Lower & upper left quadrants are both bloated (apple shape)
-Lower right is bloated (pear-shaped)
What is bloat (ruminal tympany)?
-Overdistention of the rumenoreticulum with gases of fermentation
What types of bloat (ruminal tympany) are there?
-Frothy bloat (primary ruminal tympany)
-Free gas bloat (secondary riminal tympany)
What is frothy bloat (primary ruminal tympany)?
-Gas dissolved in liquid digesta (causes foam)
What is free gas bloat (secondary ruminal tympany)?
-Gas separated from digesta
What causes free gas bloat (secondary ruminal tympany)?
-Esophageal obstruction (choke)
-Interference in nerve pathways involved in eructation
-Grain overload leading to esophagitis & rumenitis interfering with eructation
How do we “fix” free gas bloat (secondary ruminal tympany)
-Stomach tube to relieve gas pockets
-Trocar (through skin into rumen)
-Rumenotomy (surgical incision into rumen to relieve gas)
Explain frothy bloat (primary ruminal tympany)
-Foam mixed w/ ruminal contents
-Stable foam of small gas bubbles & eructation can’t occur (b/c can only eructate free gas)
-Froth gets up against cardia region & any free gas there also can’t be eructated
-High surface tension
What causes frothy bloat (primary ruminal tympany)?
High legume diets
-Soluble proteins & saponins allow small bubbles to form
Feedlot cattle
-Fine particle size of diet allows gas bubbles to form
How can we prevent & treat frothy bloat?
-Limit time on high-risk pastures (ex: legume pastures), give anti-foaming agents
-Mineral oil can treat b/c it is a surfactant & will break up the foam
What is traumatic reticuloperitonitis?
-Hardware disease
-Heavy material/foreign objects fall into the reticulum during primary rumen contractions -> reticulum contractions force sharp objects to penetrate wall -> also prevents movement of rumen contents through reticulo-omasal orifice
What are the resulting problems of traumatic reticuloperitonitis depending on direction of penetration?
-Liver abscess
-Pleuritis
-Pericarditis
-All accompanied by peritonitis
What are the clinical signs of hardware disease?
-Rumen motility slows down/stops
-Reduced appetite, milk production decreases in dairy cows
-Fever
-Abdominal pain
-Arched back
-Reluctant to move
-Abducted elbows
-Grunt on expiration
How is hardware disease diagnosed?
-Withers pinch test: grunt or hold breath
-Abdominal paracentesis
-Hemogram (complete blood count)
-Imaging
How is hardware disease treated?
Medical
-Administer a magnet
-Antibiotics
Surgical
-Rumenotomy
How is hardware disease prevented?
-Clean up the environment (baling & fence wire)
-Magnets in feed handling equipment
-Prophylactic magnets to all adult cattle
What is meant by “displaced abomasum”?
-Abomasum suspended loosely by greater & lesser omentum in right front quadrant of abdomen
Explain a LDA
-Hypomotility & gas production that causes displacement towards the left laterally towards the lumen
Explain a RDA
-Hypomotility & gas production that causes a counterclockwise rotation (when viewed from back)
-Leads to obstruction & ischemia
What factors can contribute to a displaced abomasum?
Hypomotility
-High grain diet = less motility, get more gas flowing into the abomasum
Periparturient changes in location of intra-abdominal organs
-Happens within ~14 days of calving
What determines the rumen pH?
-Intake of fermentable carbohydrates
-Buffering capacity of rumen
-Rate of VFA absorption
What happens during rumen acidosis?
-Abrupt increase in readily fermentable carbohydrates
-Rumen microflora need time to transition from cellulolytic -> amylolytic, so sudden diet change upsets rumen
What are the types of rumen acidosis?
-Subacute rumen acidosis (SARA)
-Acute rumen acidosis
What is subacute rumen acidosis (SARA)?
-pH drop not as severe & due to overall accumulation of VFAs
-Lactic acid production starts and will accumulate
What are the steps to development of SARA?
-Shortage of amylolytic bacteria allows S. bovis to grow & produce lactic acid
-Lactic acid builds up, pH drops
What are the clinical signs of SARA?
-Clinical signs not as severe, but feed intake decreases & milk production stops
This is showing signs of
-Rumen acidosis
What is acute acidosis?
-pH < 5.5
-Lactic acid accumulation, pH depression extreme, some lactic acid absorption into blood
-pH in rumen can drop as low as 4.0 causing papillae to peel (parakeratosis) - bacteria invade rumen wall
What is the treatment/prevention for SARA & acidosis?
-Feed ionophores, buffers, lactic acid utilizing bacteria
What is the primary gas produced by fermentation in the rumen?
-CO2
(2nd is methane)
Which type of bloat is associated with an obstruction interfering with eructation of gas?
-Free gas bloat (obstruction like choke)
