exam 1 lecture 13 fermentation Flashcards
1
Q
plants can take sunlight and turn it into ____ which is stored as polymers as ___
A
glucose
cellulose (polysaccharide)
hemicellulose (polysaccharide)
2
Q
cellulose
A
glucose polysaccharide
lined by Beta 1-4 linkage to form crystalline structure
not easy to breakdown (ligno-cellulose complex)
3
Q
hemicellulose
A
strings of pentose and hexose loosely bound to cellulose
4
Q
cellulose and hemicellulose are surrounded by ___
A
lignin
not a polysaccharide/carbohydrate but has a phenyl-propane base
protection of cellulose and hemicellulose
5
Q
Only microbes have the enzymes to unlock covalent linkages (expose) carbohydrates followed by ___ - fermentation
A
hydrolysis
6
Q
Colonization by microbes in the digestive tract becomes essential to exploit the ___ capacity of microbes
A
fermentative
7
Q
Microbes derive energy and nutrients during fermentation for their ___
A
growth
8
Q
___ mutual benefit between herbivorous host and microbes
A
symbiosis
9
Q
birds transfer microorganism to their young by ___
A
regurgitating food
10
Q
suitable conditions for fermentative digestion
A
Reservoir to house microbes in the digestive tract
Anaerobic environment (no oxygen allows for transfer of electrons)
pH range slightly acid to neutral ((>5.3) 6.0 to 7.0)
Passage rates are slow
Utilization of by-products and absorption of end products
11
Q
chemical conditions for fermentative digestion
A
pH ((>5.3)6.0-7.0) slightly acid to neutral
buffering systems
VFAs
12
Q
Physical conditions for fermentative digestion
A
reservoir
anaerobic environment (no oxygen) - O2 likes to be electron accepter, without it allows exchange of electrons through oxidation and reduction reactions
13
Q
___ is a region of GI tract enlarged to store food and allow microbiota to colonize and facilitate fermentation
A
reservoir
14
Q
___ are examples of foregut fermenters
A
Reticulorumen – ruminants
Pseudoruminants- not 4 chambers but 2-3
Marsupials – sacciform and tubiform –microbial colonization
Camels, ilpacas-3 stomach –small reticulum, one big rumen and leading to glandular stomach
15
Q
hindgut fermenters have modifications to the ___
A
large intestine
Cecum – Rabbit
Cecum and Colon - Horses
16
Q
foregut or hindgut reservoir are larger
A
foregut
hindgut are smaller and mostly used for fermentation of fiber
17
Q
Access to protein is minimal in rabbits and therefore microbial protein formed in caecum is passed into fecal pellets. This is gold for them and they excrete at night and practice ___
A
coprophagy (eat feces)
18
Q
in rabbit/hindgut fermenters, VFA acids formed are absorbed through the ___ epithelium
A
cecal
19
Q
why do rabbits eat their poop?
A
coprophagy
recycle nutrients
20
Q
where are microbes in a rabbit?
A
cecum- small so food can’t stay long
21
Q
where does fermentation occur in horses?
A
cecum and colon- breakdown of fiber
Caecum is temporary reservoir and colon is the major reservoir
The digestive tract is pretty long and it takes quite some time for the feed to reach cecum and colon and therefore horse has to be constantly fed to provide continuous supply of feed
Pasture/hay is major source of forage – digested in cecum, colon
Protein, starch are digested in small intestine
22
Q
fermentation in horses produce ___ where fermentation in rabbits produce ___
A
energy
energy and proteins- needs to be eaten again to absorb protein
23
Q
•The redox potential is for microbial transactions is ___
A
negative (Eh = -250 to -450 mv)
oxidation reduction reactions produce H, this is split into protons and electrons, electrons are transferred by cofactors, so that the oxidation reduction reactions happen,
the more negative = more reaction occurs = more digestibility for the animal
24
Q
•Fermentation produces metabolic ___
A
hydrogen
25
what happens to the oxygen introduced in feed and water inside the fermentation chamber?
–Diffuse across rumen and hindgut wall
–Used by facultative anaerobes
26
more grain in the diet will do what to the redox potential of the reservoir
**more grain**= easier to ferment = less reactions = **more positive**
**more fiber=** harder to ferment = more reactions, more protons and electrons = **more negative= more digestibility**
27
more grain in diet will cause the pH to do what?
drop
needs to be 6-7 for microbial growth
28
how is pH regulated in the fermentative reservoir?
volatile fatty acids from microbial growth try to lower pH make more acidic
buffers (bicarbonate and phosphate) increase pH
try to stay 5.4 for foregut fermenters (cows) and 6.0 for hindgut fermenters (horse)
29
roles of saliva in ruminants
lubrication
buffering NaHCO3
100-150 liters per day
30
roles of saliva in hindgut fermentation
moisten and soften food
flow associated with chewing
35-40 liters per day
31
foregut fermenters feed intake pattern are \_\_\_
meal based feeder
–Multiple meals per day (10) total eating time 2 to 3 hours with 7 to 12 hours ruminating
–Foregut fermenters process feed slowly
32
Equine are trickle feeders because
–16 to 18 hours a day eating to maintain a full stomach and **constant flow through GI tract**
–Hindgut fermenters can process feed more rapidly – higher passage rates than foregut fermenters
33
microbes need nitrogen to survive and get it from \_\_\_
proteins: urea, ammonia and amino acids
## Footnote
**doesn't want protein nitrogen sources- will have to waste energy breaking it down**
34
do fermenters need fats?
no, microbes can make their own fatty acids. do not need supplementation
excess fat can bind to cell walls of bacteria and inhibit microbial fermentation
35
foregut fermenters can eat
pastures, grasses, hay, silages and grain
36
horses/ hind gut fermenters can eat \_\_\_
grasses, hay and grain
37
dietary factors/ nutrients between foregut and hindgut
NPN= non protein nitrogen
38
why not feed fine food to fermenters
fine foods, too small. pass through without getting fermented
* Passage and degradation–Proportion degraded is a function of
* Kd/(Kd + Kp)
–Kd is a characteristic of the feed
–Kp is a function of body size, feed intake, and physical characteristics of the diet
39
Kd/(Kd + Kp)
**•****Passage and degradation**
–**Kd** is a characteristic of the feed
–**Kp** is a function of body size, feed intake, and physical characteristics of the diet
40
fiber digestibility is __ in foregut fermenters than hindgut fermenters
higher
41
where is starch and protein digested in a fermenter?
**hindgut=** SI and a little in the LI
**foregut=** most in the rumen, some in the SI and very little in the large bowel
42
In equines, most of dietary starch and CP are digested in the\_\_\_
small intestine
43
Both starch and protein are digested in the rumen, starch is also digested in the ___ but lower compared to rumen
lower gut
44
in a lactating cow vs dry cow, which eats more? and how long will things stay in the rumen?
lactating cows eat more
**grains: will move faster in a lactating cow** cause she is eating more and the starch can be broken down faster= eats more, digested faster = same amount of starch absorbed?
**hay:** same time in dry or lactating cow- needs to be fermented, lactation does not affect this speed
45
passage rate in equine
very fast stomach to cecum→ 3.7 hours
slow: cecum to colon → 1-3 days
46
foregut fermenter microbiome is made of
bacteria
protozoa
fungi (break down lignin in plants)
archaea (hydrogen foraging)
47
rumen bacteria form complex enzyme complexes called __ to make it easier to breakdown fiber
cellulosomes
48
rumen portozoa
50% biomass, but less in number compared to bacteria
ciliates: holotrichs (cilia throughout) and oligotrichs (cilia only at the mouth)
protozoa need help from bacteria and archaea to preform correctly
**issues:** produce H which can produce methanogens→ methane production. eat bacteria and the material they produce that would produce bacterial protein → nitrogen inefficiency
49
what would happen in protozoa were removed from rumen
**defaunation**
bacteria protein produced by bacteria would survive, because protozoa usually eat bacteria
decrease in methane gas
30% decrease in breakdown of fiber
50
anaerobic fungi in rumen
abundant on fibrous diets
zoospores swim until they grow zoosporangium and attach to fiber/plant particle and **relate to carb digestion,** grow rhizoids until big enough to release more zoospores and restart cycle
51
anaerobic fungi are mostly found in what kind of fermenters?
foregut
52
rumen archaea
scavenge hydrogen
do not contribute to feed fermentation directly
naturally form methane
Methane mitigation strategies can have negative implications on **fiber digestion and rumen fermentation**
53
rumen archaea produce methane via three pathways
Hydrogenotrophic methanogens (CO2 + H2)
Methylotrophic methanogens (Methylamides as substrates)
Aceticlastic methanogens (Acetate as substrate)
**Methane mitigation strategies can have negative implications on fiber digestion and rumen fermentation**
54
microbes need what to survice
**CO2**
**energy** (ATP released during fermentation of carbs and proteins)
**nitrogen** (ammonia, peptides, amino acids)
**minerals**
55
overview of microbial fermentation
cell wall made of cellulose and hemicellulose
break in cellulose, primary fermenter attaches and turns cellulose into oligosaccharides and polysaccharides
these then get broken down even more into **acetate, butyrate, propinoate and methane**
56
hindgut fermenters produce acetate instead of methane, why?
smaller container makes less H
acetogen will bind better then methanogens → acetate
57
\_\_\_ mitigation strategies can have negative implications on fiber digestion and rumen fermentation
Methane
58
Herbivorous animals depend on \_\_\_to digest plant materials
microbes
59
Ruminants are ___ fermenters (reticulo-rumen) and hindgut fermenters have modification in \_\_\_
foregut
caecum (rabbits) and colon (equines)
60
A ___ to store food, a pH of \_\_\_and anerobic conditions are prerequisites for microbial colonization
reservoir
6-7
61
Foregut fermenters can digest ___ whereas hindgut fermenters can ferment \_\_\_
fiber, starch and protein
good quality fiber
62
Passage rates are lower in ___ fermenters and higher in ___ fermenters.
foregut
hindgut
63
\_\_\_ rates depend on quality of feed, feed intake, feed characteristics, digestion rates and the host
Passage
64
Microbiota include bacteria, ___ and archaea
protozoa, fungi
65
Bacteria, fungi and protozoa contribute to cellulose digestion whereas ___ are hydrogen scavengers and exclusively form methane
archaea
66
The nutrient requirements of microbes are \_\_\_, ___ from ammonia or peptides and minerals
ATP released during carbohydrate fermentation
nitrogen
67
carbs are comprised of
**neutral detergent fiber** (NDF: cellulose, hemicellulose and lignin)
**Non fiber carbohydrates** (Pectin, starch and simple sugars)
68
neutral detergent fibers such as cellulose and hemicellulose is fermented \_\_\_
slowly
69
non fiber carbs such as pectin and starch are fermented \_\_\_
quickly
70
–High forage rations have higher ___ and therefore a controlled rate of fermentation
NDF
neutral detergent fiber (NDF: cellulose, hemicellulose and lignin)
slower fermentation
71
–High Grain rations contribute to readily available carbohydrates and may lead to ___ fermentation
runaway
starch and pectin (too fast breakdown)
72
particle size changes fermentation how?
physically effective NDF
too small =too fast
too big = too slow
¾ inch= happy place
needs to facilitate colonization of microbes
73
there needs to be a balance between ___ and ___ for carb fermentation
•**neutral detergent fiber** (NDF: cellulose, hemicellulose and lignin) and **Non fiber carbohydrates** (Pectin, starch and simple sugars)
74
two stages of cellulose digestion
microbial attachment (colonization)
hydrolysis (enzymatic)
75
microbial attachment stage of cellulose fermentation
colonization (1st step)
Slow process (Lag phase)- rumination (churning to increase SA and allow growth)
Specific and non-specific binding
76
hydrolysis/ enzymatic stage of fermentation
2nd stage
## Footnote
a. Endoenzymes
b. Exoenzymes
c. Multi-enzyme complexes
77
phase 1 of carb breakdown
cellulose, starch, pectin and hemicellulose get broken down and turned into pyruvate
78
phase II carb breakdown
**pyruvate → volatile fatty acids:** acetate, propionate, butyrate, CO2 and CH4
Two pathways for propionate production
**Dicarboxylic Acid:** Forage rations
**Acrylate:** Grain Rations
Runaway fermentation (high grain) can lead to accumulation of lactate; when lactate production exceeds capacity of acrylate pathway
79
bacteria fermentation will turn pyruvate into
acetate, formate, H2 and methane
80
pyruvate → butyrate
two ways: dependent and not dependent on acetate
81
amount of grain in the diet will determine how fast pyruvate → \_\_\_
propionate
82
increase in volatile fatty acids triggers what?
decrease in pH
tiggers changes in rumen epithelium
83
most VFA can be absorbed by diffusion, except for \_\_\_
butyrate
84
what happens to acetate when it leaves the rumen
used for oxidation, fat
important as precursor for milk fat
85
what happens to propionate when it leaves the rumen
used liver → glucose
important as determinant of milk volume
86
what happens to butyrate when it leaves the rumen
portal vein → beta-OH-butyrate
used for oxidation, fat
stimulates rumen development and papillae length
87
why is fiber more important for dairy cow
breakdown of fiber → acetate and butyrate → needed for milk fat production
88
why can beef cows eat more grain then dairy?
grain= propionate- gluconeogenic
fiber = acetate and butyrate= needed for milk fat production
89
carb digestion in equines is a balance between ___ and \_\_\_
forage (fiber) and grains
90
forages/fiber is fermented in the __ of a horse
cecum and colon
91
in horses, if grains are fed at a rate beyond the digestive capacity of the small intestine can lead to \_\_\_
colic, diarrhea, laminitis and **microbial dysbiosis** (runaway fermentation)
92
\_\_\_produced by carb digestion in horses provided immediate supply of energy.
VFA
93
•The major reason for microbial fermentation is ___ digestion
fiber
94
•Fiber carbohydrates are ___ and hemicellulose.
cellulose
95
•Carbohydrate are fermented to ___ that serve as metabolic fuel. Methane is a by-product of fermentation.
VFA
96
•\_\_\_\_ are the major VFA produced by carb fermentation.
Acetate, propionate and butyrate
97
High fiber yields ___ and more grain increases \_\_\_.
acetate
propionate
98
Acetate and butyrate are needed for ___ or meat. Propionate is gluconeogenic and correlated with \_\_\_.
fatty acid synthesis in milk
milk yield.
99
•More fiber in the diet is good for microbes and is sufficient for \_\_\_
maintenance
100
Grain is needed to enhance fermentation by increasing molar proportion of \_\_\_
propionate.
101
Excessive grain can lead to ___ formation, drop in pH and causes microbial dysbiosis in both foregut and hindgut fermenters. A balance between fiber and grain is critical for microbial efficiency
lactate
102
Optimal particle ___ is needed for rumen mat formation and facilitate microbial colonization
size
103
Microbes need protein in the form of ___ for their growth.
nitrogen
104
dietary crude protein is broken into two (true protein and NPN) what are these
**true protein:** can not be broken down by microbes, moves through foregut to be digested later on for animals with higher protein requirments
**NPN (non protein nitrogen):** needed to feed microbes so they can breakdown other things like fiber
105
where can microbes get nitrogen
from the diet NPN
from recycled microbial protein (bacteria and protozoa)
endogenous nitrogen: saliva/ dead cells (urea and abraded epithelial cells)
106
Microbes prefer to utilize \_\_\_from ammonia and so all nitrogen sources are converted to ammonia
nitrogen
107
1st step of protein metabolism is proteolysis, which is \_\_\_
convert nitrogen source to ammonia
108
microbial protein synthesis
The nitrogen source from **ammonia** forms the building block for microbial protein formation
Need **fermentable carbohydrate to supply ATP** for microbial protein synthesis
Beneficial to microbes and the host
Microbial protein synthesis occurs in both foregut and hindgut fermenters to support microbial growth
Microbial protein is utilized **only in foregut fermenters**. It is not absorbed but excreted in hindgut fermenters.
109
proteins are broken into ammonia by __ and \_\_
bacteria and Protozoa
110
2nd step of protein synthesis in the rumen
ammonia + energy → microbial cells
## Footnote
Microbial protein synthesis requires N sources (ammonia, peptides, aminoacids) plus a **continuous supply of fermentable carbohydrates to supply energy** along with growth factors
111
too little energy to push ammonia to microbical protein can result in
ammonia/urea toxicity
112
•Protein hydrolysis to ammonia and ammonia capture to microbial protein should go hand in hand to avoid \_\_\_.
nitrogen inefficiency
113
•Synchronization of protein degradation and supply of ___ is important.
fermentable carbohydrate
114
•Diets are formulated to increase microbial ___ (cheap and best quality) for ruminants
protein
115
•Microbial protein is of little value to \_\_\_fermenters
hindgut
116
As the rate of passage from the rumen increases there is greater opportunity for ___ to pass out of the rumen.
bacteria
117
Microbes synthesize their own ___ and there is no need for dietary supplementation
fatty acids
118
Fatty acids are present as complex \_\_\_(galactolipids, phospholipids in forages)
lipids
119
Microbes cannot tolerate more than \_\_% in dietary lipids
3
120
Excessive\_\_\_ can be harmful to microbes and reduce their activity
lipids
121
To avoid toxicity to microbes, protected ___ are added to ruminant diets to bypass the rumen but available in lower gut
fats
122
In\_\_\_ fermenters, lipids are not accessible to microbes
hindgut
123
•Lipolysis: Complex lipids are hydrolyzed to ___ and glycerol by lipolytic bacteria
free fatty acids
124
**Glycerol is converted to VFA’s; Free fatty acids are ___ in nature**
**unsaturated**
125
\_\_\_ : Hydrolyze triglycerides and phospholipids
Anerovibrio lipolytica
126
\_\_\_ Hydrolyze galactolipids, phospholipids, and sulfolipids
Butyrvibrio fibrisolvens
127
\_\_\_: Conversion of unsaturated FA to saturated FA resulting in the formation of several isomers termed as bioactive fats
Biohydrogenation
128
***cis-*****9,*****trans-*****11 CLA**
rumenic acid
Anticarcinogenic
Produced in mammary gland
from vaccenic acid by delta-9 desaturase
75% to 90% of CLA in milk
129
***trans-*****10,*****cis-*****12 CLA**
Reduction in body fat
Produced in rumen
Significant reduction in milk fat
130
in high fiber diet:
linoleic acid → stearic acid
**cis9 trans 11**
131
in a high grain diet = more energy linoleic acid → stearic acid
**skips steps goes through trans10cis12**
* Increasing fermentable carbohydrate at the expense of fiber coupled with higher lipid concentrations triggers alternate pathway
* Alters microbiota leading to production of Trans-10, cis-12 18:2 CLA and trans-10 isomer
**•****These two isomers inhibit milk fat synthesis in the mammary gland and lead to milk fat depression in dairy cows**
132
ways to mess up fermentative digestion
* Excessive fermentation of starch
* Low pH in rumen or cecum (colon)
* Production of amines
* Production of endotoxins
* Laminitis, rumen parakeratosis, liver abscesses, lung abscesses
* Laminitis and colic
133
SARA
Sub-acute ruminal acidosis (SARA)
from abrupt change in diet
lactic acid increases, pH drops and fermentation is disturbed
134
ideal pH for microbs
6.6-6.8 (range 5.5 to 7)
## Footnote
pH \> 6 – Fiber digesters; pH\< 6 – amylolytic digesters;
pH – 5.5 lactic acid producers
(opportunists) – dysbiosis in the rumen microbiota (SARA, frothy bloat)
135
\_\_\_ refers to abdominal pain and is the consequence of all forms of gastrointestinal diseases or problems
Colic
136
About 10-11% of horses suffer from colic and about \_\_\_% cases are fatal – approximately $16 million loses due to colic
11
137
Dietary factors – high grain, low fiber, \_\_\_feed changes, moldy feeds are some major causes for colic
abrupt
138
Changes in ___ can lead to torsion, twisting, ulcers and uterine pain
microbiota
139
what happens to microbes during colic
Overall we found that healthy commensals were reduced and bacteria with unknown functions have increased.
140
best way to reduce colic
* Gradual adaptation to higher grain diets–Over a 1 to 2 weeks to increase concentrate feeding–Highest risk of GI upset in horse is 7 days post-increased grain feeding
* Equine maximal grain rate – 0.4% of BW/meal, usually two meals/day
* Cow – \<= 60% of total diet DM as concentrate
