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2025 Exam block 5 > Exam 3: Lecture 31 - Ruminant Digestive Physiology 1 > Flashcards

Exam 3: Lecture 31 - Ruminant Digestive Physiology 1 Flashcards

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1
Q

How does the ruminant digestive strategy allow protection from predators?

A

-Ingest enormous quantities of forage in a short time, thus minimizing exposure in the open
-Spend maximal time ruminating in the protection of trees & rocks

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2
Q

What is/are the forestomach of the ruminant?

A

-Rumen
-Reticulum
-Omasum

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3
Q

What is/are the gastric stomach(s) of ruminants?

A

-Abomasum

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4
Q

What is important about the epithelium of the forestomachs of the rumen?

A

Stratified squamous epithelium
-No glands
-Pillars & papillae

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5
Q

How is pre-gastric fermentation accomplished in ruminants GIT?

A

-By microbes (bacteria, protozoa, fungi)

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6
Q

What is the overall capacity of the ruminant GIT?

A

-60-80 gallons

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7
Q

_____ have no omasum

A

-Pseudoruminants

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8
Q

What are the ruminants energy source?

A

-From VFAs

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9
Q

What are horses energy source?

A

-Starch digestion in SI + some VFAs from hindgut

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10
Q

What are the ruminant species?

A

-Cattle
-Bison
-Sheep
-Antelope
-Goats
-Deer
-Elk

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11
Q

Rumination = _____ + ______

A

-Rumination = regurgitation + remastication

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12
Q

How is microbial fermentation accomplished?

A

-Bacteria
-Fungi
-Yeast
-Protozoa

(Bacteria & protozoa are the biggest ones!)

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13
Q

Ruminants chew _______ times/24 hours

A

30,000-50,000

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14
Q

Where are the nasolabial glands located in bovine?

A

-Dermis of muzzle

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15
Q

What are the major salivary glands of bovine?

A

-Parotid (produces serous)
-Mandibular (produces mixed)
-Sublingual (produces mixed)

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16
Q

Is mucus thick or thin when talking about salivary glands and why?

A

-Thick b/c lots of glycoproteins

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17
Q

How much saliva is produced per day?

A

-40 gallons (~150 liters) on average per day

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18
Q

The amount of saliva produced per day depends on

A

-Size of animal
-Type of food
-Water already in food

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19
Q

What is the composition of saliva?

A

-Bicarb (important for buffering)
-Urea
-K
-Phosphate
-Cl

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20
Q

What are the functions of saliva?

A

-Buffering
-Add moisture
-Lipase (little bit)

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21
Q

What environmental conditions are needed to support fermentation?

A

-Appropriate substrate
-Temperature around 37 C
-Osmolality near 300 mOsm
-Anaerobic conditions
-Frequent mixing of ingesta
-Particle size reduction
-Indigestible material removal
-Synchronized movement of fermented content to intestine
-VFA must be buffered to maintain neutral pH

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22
Q

Why is appropriate substrate needed to support fermentation?

A

-Need to also feed the microbes in the rumen (not just feed the animal)
-Need energy & Nitrogen
-Starch, cellulose, Protein/N (urea)

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23
Q

How do we get frequent mixing of ingesta to support fermentation?

A

-Rumen motility (need normal rumen contractions)

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24
Q

What is an example of indigestible material removal?

A

-Lignin (associated w/ cellulose)
-More lignin in grass/hay, the less even cellulose can be digested

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25
What is the primary site of fermentation in ruminants?
-Rumen -60-75% of digestion
26
Does the rumen ferment cellulolytic or amylolytic bacterial species?
-Primarily cellulolytic
27
Cellulolytic bacterial species prefer ______ while amylolytic bacterial species prefer ______
-Cellulolytic = grasses/plants -Amylolytic = starch/sugars
28
What are the end products of rumen fermentation?
-Acetate -Propionate -Butyrate
29
What do the end products of rumen fermentation serve as?
-Energy sources to the animal
30
There is more ____ produced by rumen fermentation on a fiber diet, while more ____ is produced by rumen fermentation on a grain diet
acetate, fiber (acetate is still the largest produced)
31
What are the by-products of rumen fermentation?
-CH4, CO2, heat
32
What do the papillae & extensive capillaries of the rumen do?
-Increase surface area -Size varies -Absorb VFAs (stabilize rumen pH)
33
What do the muscular rumen pillars do?
-Help w/ contraction occurring b/c squeeze together & help area mix well
34
What do the muscular pillar and folds of the rumen do in mixing?
-Help divide rumen into different areas
35
Where does the primary contraction start in ruminants?
-Starts in reticulum & moves caudally
36
____ has a honeycomb appearance
Reticulum
37
What is shown?
Reticulum
38
What are the major functions of the reticulum?
-Form bolus for regurgitation (when animal lays down to ruminate) -Move particles to the omasum (typically small enough to exit the rumen) -Move particles to rumen (b/c need to retain larger particles for more rumination to occur)
39
What disease can happen in the reticulum?
-Hardware disease (bovine traumatic reticuloperitonitis) -Reticulum sits a bit lower than rest of rumen, so things fall here
40
Material from the rumen passes into the omasum via the _____
-Reticulo-omasal orifice
41
What part of the ruminant stomach has "many plies"?
-Omasum
42
What does the omasum do?
-Regulates passage of digesta into lower tract -Some absorption of water & VFAs
43
Which stomach compartment is the gastric stomach with many folds?
-Abomasum
44
What does the abomasum do?
Gastric glands to secrete HCl -Acidity kills microbes washing in from rumen - starts digestion -Microbes provide protein (essential AA) to the animal) Secretion of pepsinogen -Hydrolyzes microbial & dietary protein
45
There are about ____/minute abomasal contractions
2-3/minute
46
Why are abomasal contractions important?
-Mixing, material exits to SI, and drive gas back to rumen -Have a lot of CO2 dissolved in rumen fluid that becomes liberated to free gas when meets acid in abomasum (free gas build up in abomasum = bad)
47
Rumen forages contain
-Cellulose -Hemicellulose -Sugars -Starch -Protein -Lignin
48
What are examples of rumen forages?
-Grass, hay -Legumes -Brush & weeds -Silage -Byproducts - i.e. corn stalks, citrus pulp, peanut straw
49
Concentrates (grain) contain mostly
-Starch -Protein -Sugars
50
What are some examples of concentrates (grain)?
-Grain -Soybean meal/whole soybeans -Other seed meals
51
What is rumen fermentation?
-Microorganism-mediated transformation from one nutrient compound to another -Ex: taking cellulose & producing acetate -Ex: taking starch & producing propionate
52
What do microflora do?
-Attach & grow on the substrate, utilize metabolites & secrete metabolites
53
What are the rumen microflora?
-Bacteria -Protozoa -Fungi
54
**Primarily feed the ____ - then the ____**
**Primarily feed the flora - then the cow**
55
What happens to the dead rumen microbes?
-Dead microbes flow to intestines and are digested
56
What are the rumen layers from bottom to top?
-Small high-density particles -Liquid -Fiber mat (provides scratch factor - everything in this layer has large, low-density particles) -Gas layer (want it near the esophagus so the cow can eruptate)
57
What products undergo fermentation in the rumen?
-Monosaccharides -Disaccharides -Starch -Cellulose -Other sugars
58
What is the % of carbohyrates fermented in rumen to short chain (volatile) fatty acids (VFAs)?
-60% Acetate -> higher with forage diets -30% Propionate -> higher with grain diets -10% Butyrate
59
Sugars -> _____
VFA
60
Starch -> ____ -> _____
Starch -> glucose -> VFA
61
Cellulose -> _____ -> _____
Cellulose -> glucose -> VFA
62
Lignin -> ____
Undigested (microbes can't deal with)
63
Ruminants use ___ for energy
VFA
64
Ruminants have a lower ____ than most non-ruminants
Blood glucose
65
How does **gluconeogenesis** work in ruminants?
-Use propionate (from fermentation) to make glucose
66
Fat synthesis in ruminants uses
Acetate
67
Most acetate is transformed to ____, and most propionate is used to _____
Fat, most propionate is used to make glucose
68
Proteins are fermented to
-Peptides -Amino Acids -Ammonia (a lot converted to this) -Branched-chain VFAs
69
_____ use protein components and metabolites in synthesizing cell wall & cytoplasmic proteins
Microbes
70
Where are dead microflora digested?
-Small intestine
71
____ provide the highest quality protein possible
Microbes -They contain essential amino acids the animal needs
72
T/F: You can feed low quality proteins or metabolites (urea) & cow absorbs highest quality amino acids from small intestines
TRUE! -Cow will still be fine b/c will get essential AAs from microbes
73
There is major ____ cycling in ruminants
Urea
74
___ is produced in the rumen from protein fermentation
Ammonia
75
What happens to ammonia produced in the rumen from protein fermentation?
-**Immediately utilized by microbes OR absorbed & converted to urea by liver**
76
What are the fates of urea in ruminants?
-Excreted by kidney -Recycled to saliva* -Recycled to rumen*
77
What are the components of rumen motility?
-Primary contractions -Secondary contractions -Reticular contractions
78
Explain the primary contractions in the rumen
-Major coordinated movements cranial to caudal primarily for **mixing** -About 2 per minute
79
Explain the secondary contractions in the rumen
-Caudal to cranial primarily to **eructate gas** (pushing gas into esophagus)
80
Explain the reticular contractions in the rumen
-Associated w/ cud chewing -Help form bolus & bring it to esophagus for regurgitation & rumination
81
What is the importance of rumination?
-Reduces particle size -Increases surface area -Adds saliva
82
Particles need to be ____ to pass from the rumen
< 1 mm
83
What are the 4 main components of rumination?
-Regurgitation -Reinsalivation -Remastication -Reswallowing
84
Explain regurgitation in rumination
-Initiated by reticular contraction **AND** relaxation of distal esophageal sphincter -Allows bolus to enter esophagus & go to mouth and remastication, reinsalivation, etc. occurs
85
When does rumination happen?
-Occurs when animal is resting (laying down) -Begins 30-90 minutes after eating (usually) -Ruminate up to 10 hrs/day (will not ruminate as much on a high grain diet)
86
How is the process of rumination initiated?
-By an "extra" contraction of reticulum that pushes ingesta into the area of the cardia
87
What is the process of rumination?
-Distal esophageal sphincter opens -Inspiratory excursion w/ glottis closed causing negative pressure in intrathoracic esophagus -Bolus of ingesta moves into esophagus
88
What does reverse peristalsis do?
-"Vomits" bolus into mouth
89
What happens during reinsalivation, remastication & reswallowing?
-Fluids are squeezed out of bolus & swallowed, ingesta chewed & additional saliva added -Cud swallowed & process repeated -Process is a complex reflex control mediated by medulla
90
What provides the "scratch factor" and why is this important?
-Epithelial receptors in the reticulum provide this -Important to provide large enough fiber so they can get this "scratch factor"
91
What is the ideal pH for the rumen environment?
-6.8
92
Which VFA is used by ruminants for fat synthesis?
-Acetate

2025 Exam block 5 (25 decks)

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