Metabolic disturbances

over distension of the rumen and reticulum with gases of fermentation

ruminal tympany

frothy bloat- of dietary origin (occurs in cattle on pasture and feedlot cattle on high grain diets)

free gas bloat- physical or physiological interference with eructation

Bloat

Within 15 min of feeding

• unfed 0.2L/min
• fed 2.0L/min

soaking, fermentation, and mixing

• Pump that causes food to move in and out of rumen
• directs ingesta to rumen or from rumen to omasum
• Floods cardia prior to regurgitation

Grinds and triturates (squeezes out fluid) rumen contents located within folds.

• True stomach- functions like non-ruminants 
• starts digestion of degraded concentrates and roughages 
• starts digestion of microbes of fermentation

process by which gas from the forestomach is removed via the esophagus to the pharynx

~1min

mechanoreceptors in dorsal sac of rumen and cardia sense gas pressure- goes to CNS: reflex center in medulla

• rumen contracts-moves gas bubble forward
• reticulum relaxes
• cardia opens 
• gas released (most inspired by lungs)

Gas bubbles produced are very tiny and thus they are not sensed by mechanoreceptors in the rumen or cardia, which prevents eructation and = BLOAT!!

Reticulum to rumen (coordinated waves of contractions and relaxations)

Rumen only- associated with eructation.

• Intraesophageal foreign body (may cause scarring(stenosis))
• Paraesophageal obstruction- swollen lymph nodes
• Diaphragmatic hernia, muscle trauma, toxins
• Interference of nerve pathways
• Metabolic derangements

tuberculosis, bovine leukosis virus and chronic pneumonia

• injury to vagal nerve
• injury to central processing centers for digestion (medulla)

hypocalcemia, acidosis

Rapid digestion of plants rich in cytoplasmic protein causes a release of plant proteins that act as frothing agents and form many tiny gas bubbles.

In the spring and fall when pastures are lush.

• legumes (alfalfa, landino clover)> red and white clover>crimson and subterranean clovers
• Also cereal crops (young plants), cabbage, canola, peas and beans

legumes with high concentrations of tannin (Sainfoin and Lotus)- precipitate protein

Production is rushed, high grain diets are fed 90% grain 10% forage

• greater energy density
• easy to transport
• ability to manipulate blend/diet easily
• demand for fatty, marbled meat

• high energy source that cattle are not accustomed to
• rumen can accommodate large quantities of forage as it is broken down over a 12-24 hour time period
• microbial fermentation changes from slow ( cellulose and hemicellulose) to rapid (starch)
• Bacteria grow rapidly in starch and produce a sick ass slime (excessive mucopolysaccarides)- which form froth and viscous ruminal fluid
• Alters feed stratification (layers of gas, liquid, solid in rumen)
• Streptococcus bovis like high starch and sugar concentrations and produce lactic acid that can lead to bloat
• A drop in the number of protozoa can also lead to bloat as they are responsible for engulfing bacteria and starch

• - respiratory and/or cardiovascular failure
• - absorption of toxic gases, toxic amine (histamine) and hydrogen sulfide

BLOAT LINE- demarcation between bloodless distal esophagus and the congested proximal esophagus at thoracic inlet

remove foreign body

• -trochar in caudal dorsal rumen (left paralumbar fossa)
• - De-gas by placing a stomach tube (for free gas bloat)
• -Anti-foaming agent (aka detergent)- works best for pasture bloat

• -watch diet: lower grain content, don't use lush pasture
• - processing: don't make feed fine or processed
• -use more forage in diet- reduces fermentation rate, increases pH and increases salivation( antifoaming properties)
• -add ionophores (inhibits growth of gram positive bacteria (steptococcus and lactobacillus)

A decrease in the alkali in body fluids relative to acid content.

continuum of change

acute or chronic

• rumen pH of 4-5
• rapid increase of lactic acid (D lactate 50-300 uM (normal=5uM))
• increase in Gram positive bacteria (lactate producers)
• decrease in Gram negative bacteria & protozoa
• Physiological change

• rumen stasis
• dehydration
• acidosis leading to coma and death

chronic acidosis

decrease in food intake

• Decrease in protozoa
• pH: 5.0-5.5

Increased starch- increases glucose concentration in the rumen

Decreased forage- shorter eating time, less salivation (buffer) and faster fermentation and digestion

Increase pyruvate which increases the substrate for increased lactate = decreased pH

• Increased D-lactate50-300uM- metabolizes 1/5 rate of L-lactate and is a potent neurotoxin 
• can cause ataxia, lethargy, depression/ confusion, nystagmus

Increase VFAs = decreased pH, also other microbes involved in acidosis will release ethanol, methanol, histamine, tyramine and endotoxin

Drop in pH due to rumen, reticulum or omasum injury

swelling of the rumen due to lactic acid

Swelling of the rumen due to the presence of a fungal infection

12-32%

• decrease in animal performance
• lowers carcass yield- not growing as well

Wasting of grey matter of the brain.

Yes, polioencephalomalacia increases with rumen acidosis.

bacteria that produces thiaminase I: forms thiamin analogs that compete for thiamine= get polioencephalomalacia

blind, down, convulsions, hypermetria, staggering

• Aspergillus
• Zygomycetes

Fusobacterium necrophorum

Increased osmolarity- causes fermentation products in the rumen such as lactate, VFAs, metabolites and pyruvate to withdraw large amounts of water from blood= severe dehydration

Absorption of fermentation products such as VFAs, metabolites, lactate and pyruvate in the intestine. Also causes withdraw of large amounts of water from blood = severe dehydration and diarrhea.

decreased blood pH= severe acidosis

Increased blood osmolarity (hemoconcentration)- associated with laminitis

endotoxin release of gram negative bacteria-following a drop in rumen pH

Excretion??

• Decrease rate of introducing grain
• Increase roughage
• Ionophores (monensin good choice)
• Add Buffers (bicarbonates) to feed