rumen fermentation power point presentation

7/27/2019 Rumen Fermentation power point presentation

1/49

RumenFermentation


2/49

Rumen Fermentation Worlds largest

commercial

fermentation space 100 billion liters or

rumen volume indomestic animals

1010to 1012

cells/mL 200 liters (50

gallons) in one cow


3/49

Ruminants Continuous culture fermenters

Input and output

Lignocellulosic substrates digested Cellulase complex Hemicellulases Lysozyme

Nitrogen capture (NPN) 8 x 1015mouths to feed

Because of these microbial enzymes, ruminants can utilize feedstuffs

that provide little to no nutritional benefit to nonruminants


4/49

4 Steps of Rumination Regurgitation

reverse peristalsis carries food to mouth

Remastication liquid squeezed from bolus and

swallowed

bolus chewed

Reinsalivation adding more saliva

Redeglution swallowing bolus and liquid


5/49

Rumination Allows animal to forage and eat food rapidly,

and then store for later digestion

Reduces particle size only small particles leave reticulorumen

Increases surface area for microbial

attachment and digestion/fermentation Breaks down impervious plant walls

Further stimulation of saliva flow (bufferrumen)


6/49

Rumination Time

Average times for a grazing animal

Eating8 hours

Ruminating8 hours

Resting8 hours

Ruminating time is quite variable

Reducing forage:concentrate decreases rumination Reducing particle size of forage decreases time

spent ruminating


7/49

Mechanism of Rumination: Regurgitation

Stimulusdigesta in fiber mat scratching surfacenear cardiac sphincter

Contraction of the reticulum forces digesta to cardia Animal inhales with epiglottis closed to produce a

vacuum Cardia sphincter opens and esophagus dilates

Negative pressure (vacuum) sucks digesta into esophagus

Rapid reverse peristalsis moves digesta to mouth


8/49

Mechanism of Rumination: Remastication,

Reinsalivation, and Redeglutition Bolus is rechewed

Chewing is slower and more deliberate than duringinitial eating phase

Digesta reinsalivated Parotid glands secrete more saliva during rumination

than eating Saliva from parotid glands secrete more NaHCO3

-thanother glands

Reswallowing After reswallowing, the rumen contracts to move

swallowed bolus into the rumen


9/49


10/49

Reducing Particle Size of

Ingested Feeds Chewing during eating (minimal)

Preparation for swallowing

Release soluble constituents

Damage plant tissues for microbial attachment

Chewing during rumination (extensive)

Decrease particle size for passage

Damage plant tissues for microbial attachment

Microbial digestion

Reticuloruminal contractions


11/49

Rumen Contractions

Inoculate incoming feed with microbes

Mix contents

Minimize effects of stratification Move fermentation products (VFAs) to

rumen wall

Particle sorting and passage of smallparticles to omasum

Rumination

Eructation of fermentation gases


12/49


13/49

Need for Eructation

Peak gas productionoccurs 30 min to 2 hr post-

feeding (12-27 liters/min) Average is 1-2 liters/min

Approximately 30% ofCO2produced in rumen isabsorbed into blood andremoved through the lungs

Only 20% of the CH4isremoved through the lungs

Composition of rumen gas

__Gas__ _%__CO2 65.35

CH4(variable) 27.76

N2 7.00

O2 (at wall) .56

H2 .18

H2S .01


14/49

Control of Eructation

Stimulus Gaseous distension of the reticulum and rumen

Esophagus dilates & animal belches

12-30 L per minute for cattle 3-17 times per minute

Inhibition Presence of digesta near the cardiac sphincter

Affects all three sphincters

Protective mechanism to prevent digesta from entering lungs Epinephrine

Histamine

Inhibition of eructation will cause the animals to bloat Ruminal pressures will increase to 45 to 100 mm Hg

Stable froth or foam formed in rumen


15/49

Why Worry about Rumen Microbes?Microbes make ruminants less efficient!!

Aerobic fermentation:

Anaerobic fermentation:

Glucose + O2 ATP + CO2+ H2O

Glucose acetic acid + propionic acid + butyric acid+ CO2+ H2O + CH4+ Heat


16/49

Feed InVFA

Microbial Protein

Vitamins

The nutr ients presented to theanimal after ruminal fermentation

are very different than those enter ing

the rumen as feed

Feed the Microbes, Let the Microbes Feed the Ruminant!


17/49

Rumen Digestion and FermentationCO2VFA

Degradable Rumen Microbial cellsFeed microbes NH3CH4HeatLong-chain

fatty acidsH2S


18/49

Rumen MicroorganismsNutritional Requirements

CO2

Energy

End products from digestion of structural carbohydrates

fermentation of sugars

Nitrogen

Ammonia (majority of nitrogen needs)

Amino acids (cellulolytic bacteria)

Minerals

Co, S, P, Na, K, Ca, Mg, Mn, Fe, Zn, Mo, Se

Vitamins

None required in mixed cultures


19/49

Symbiotic Relationship Microbes provide to the ruminant

Digestion of cellulose and hemicellulose

Provision of high quality protein

Production of VFA

Provision of B vitamins

Detoxification of toxic compounds


20/49


Digestion of cellulose and hemicellulose

Cellulases are all of microbial origin

Without microbes, ruminants would not beable to use forage crops such as pasture, hayor silage


21/49


Provision of high quality protein

50-80% of absorbed N is from microbes Improved microbial efficiency will provide more

microbial protein

Can get over 3 kg of microbial protein per day

High biological value protein source Amino acid pattern is very similar to that required by

the ruminant animal


22/49


Microbes as a feed source

Bacteria and protozoa washed out of the rumento omasum and into the abomasum

Acidic environment kills microorganisms

Digested and absorbed the same as any other feed

source in stomach and small intestine Provide amino acids and some energy


23/49

Microbes provide to the ruminantEnergy!!!

VFA 70%Microbial cells 10%

Digestible unfermented feed 20%

No glucose available for the ruminant

Concentration of VFA

in rumen = 50 to 125 uM/ml

Symbiotic Relationship


24/49


Provision of B vitamins

Meets the ruminants requirements under mostconditions

Some supplementation, such as niacin, may bebeneficial in early lactation dairy cows


25/49


Detoxification of toxic compounds

Example: Mimosine in Leucaena causes problems

poor growth, reproduction and hair loss

Hawaiian ruminants, but not those from Australia,have microbes that degrade mimosine so Leucaena

could be fed Transferred rumen fluid to Australia

Inoculated rumen

Fed Leucaena safely to Australian ruminants!


26/49

Symbiotic Relationship Ruminants provide to microbes

Housing

Garbage removal

Nutrients

Optimal environment for growth


27/49


Housing

Reliable heat (39 2C) Fluid environment (free water intake)

85 to 90% water

Guaranteed for 18 to 96 hours depending ondiet and type of animal

Straw-fed water buffalolongest rumen residencetime for microbes

Small selective browsers (mouse deer or duiker)shortest residence time for microbes


28/49


Garbage removal

Absorption of VFA Energy to ruminant

Eructation

CO2and CH4

Passage of indigestible residue and microbes tolower GI tract

Rumen mixing to separate and settle small particles


29/49


Nutrients

Substrates come from feedstuffs that animalconsumes

Saliva provides urea (N source for bacteria)


30/49


Optimal environment for growth Reduced environment (little to no oxygen)

Strict anaerobic microbes in rumen interior Functional anaerobes near rumen wall

pH 6.0 to 7.0

Saliva contains bicarbonate and phosphate buffers

Cows produce up to 50 gallons of saliva daily

Continuously secreted

More added during eating and rumination

Cow ruminates 10-12 hours/day

Decreases in particle size of forage reduce need forrumination, decrease chewing time, decrease salivaproduction, and rumen pH plummets


31/49


32/49


Optimal environment (pH)

If pH 5.7 rather than 6.5 50% less microbial synthesis

Cellulolytic bacteria function best at pH ~6.8

Rate of structural carbohydrate use is decreased

Amylolytic bacteria function best at pH ~5.8 More lactate and less acetate is produced

Further downward pH spiral

In concentrate selectors (like deer), parotid

salivary glands are 0.3% of body weight


33/49

Bacteria and pH Tolerance

Species Type pH

Ruminococcus flavefaciens

Fibrobacter succinogenes

Megasphaera elsdenii

Streptococcus bovis

fiber

fiber

lactate user

lactate producer

6.15

6

4.9

4.55


34/49

Microbes% of mass Generation

intervalNo./mL

Bacteria 60-90 20 min 25-80billion

Protozoa 10-40 8-36 h 200-500

thousandFungi 5-10 24 h minimal


35/49

Rumen Microbes Bacteria

>200 species with many subspecies

25 species at concentrations >107/mL

1010to 1012cells/mL

99.5% obligate anaerobes


36/49

Groups of bacteria in the rumenFree-living in the liquid phaseLoosely associated with feed particlesFirmly adhered to feed particlesAssociated with rumen epitheliumAttached to surface of protozoa and fungi

Environmental Niches for Bacteria


37/49

Allows bacteria to colonize the digestible surface offeed particles

Brings enzymes (from microbes) and substrate (from

feedstuff) togetherProtects microbial enzymes from proteases in the rumen

If attachment prevented or reduced, digestion ofcellulose greatly reduced

Retention time of microbes in the rumen is increased to

prolong digestionReduces predatory activity of protozoaOver-feeding fat to ruminants can coat forages, reducingbacterial attachment

Benefits of Bacterial Attachment


38/49

Rumen Microbes Protozoa

Large (20-200 microns) unicellular

organisms Ingest bacteria and feed particles

Engulf feed particles and digest

carbohydrates, proteins and fats Numbers affected by diet


39/49

Entodinium (Rumen Protozoa)


40/49

Rumen Microbes Fungi

Known only for about 20 years

Numbers usually low

Digest recalcitrant fiber


41/49

Bacterial Populations Cellulolytic bacteria (fiber digesters)

digest cellulose

require pH 6-7 utilize N in form of NH3

require S for synthesis of sulfur-containing aminoacids (cysteine and methionine)

produce acetate, propionate, little butyrate, CO2 predominate from roughage diets


42/49

Microbial Populations Amylolytic bacteria (starch, sugar digesters)

digest starch

require pH 5-6 utilize N as NH3or peptides

produce propionate, butyrate and lactate

predominate from grain diets

rapid change to grain diet causes lactic acidosis(rapidly decreases pH)


43/49

Microbial Populations Methane-producing bacteria

produce methane (CH4)

utilized by microbes for energy

represent loss of energy to animal

released by eructation


44/49

Location of Microbes

RumenWall

RumenFluid

Fiber Mat

Gas Phase


45/49

Dietary Factors That Reduce

Microbial Growth Rapid, dramatic ration changes

Takes 3-4 weeks for microbes to stabilize

Restricted amounts of feed

Excessive unsaturated fat

Bacteria do not use fat for energy

Inhibit fiber digestion and microbial growth

Different types of fat have different effects


46/49

Dietary Factors That Reduce

Microbial Growth Excessive non-structural carbohydrate

Lowers rumen pH (rumen acidosis)

Slug feeding Feed barley or wheat (rapidly fermented)

To prevent acidosis, must balance lactate usersand producers


47/49

Dietary Factors That Maximize

Microbial Growth Maximum dry matter intake

Balanced carbohydrate and protein

fractions at the same time Bacteria need both energy and N for amino

acid synthesis

Gradual ration changes

Feed available at all times Maintains stable rumen pH


48/49


49/49

Rumen Function Overview

rumen fermentation power point presentation

Documents