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VET272 > Rumen / Digestion and Absorption > Flashcards

Rumen / Digestion and Absorption Flashcards

1
Q

Name the Two Processes of Digestion and explain what the processes are.

A
  • Mechanical processes
    • Chewing, Mixing and peristalsis
  • Chemical/Enxymic processes
    • Animal Secretions; Enzymic Digestion
    • Microbial organisms; microbial fermentation
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2
Q

Compare the digestive strategies of Carnivores, Herbivores, and Omnivores

A
  • Carnivores
    • Digestion in mainly enzymatic in natuyre
  • Herbivores:
    • Ruminants - Extensive microbial fermentatin occurs before digestion by enzymes in abomasum and small intestine: some hiundgut (<10%) microbial fermentation
    • Hindgut fermenters - Digestive enzymes in stomach and small intestine followed by microbial fermentation in distal part of digestive tract (eg horse)
  • Omnivores:
    • Digestion mainly enzymatic in stomach and small intestine
    • variable microbial fermentation in large intestine (eg many grains contain fermentable soluble fibre)
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3
Q
A
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4
Q

Describe the structures in the upper digestive tract in ruminants

A
  • Mouth
    • Cutting and grinding teeth
    • Saliva production
  • Oesophagus
    • Long Tube
  • Reticulo-rumen
    • Sacs; papillae
  • Omasum
    • Bookleaf structure
  • Abomasum
    • Acidified
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5
Q

What part of a ruminant’s stomach is this?

A

Endothelium of the Reticulem

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6
Q

Where is this structure found and what is it

A

Rumen Papillae

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7
Q

Where is this found?

A

Omasum

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8
Q
  1. What is the constituents of Saliva?
  2. What is the function of Saliva?
A
  1. Constituents
    • water
    • mucins
    • inorganic ions; Na+, K+, Ca2+, HCO3-, HPO4-, Cl-
    • Proteins
    • Enzymes (amylase in humans)
    • Urea (ruminants)
  2. Function
    • Lubrication
    • Buffering
    • Nutrient Recycling (N in ruminants)
    • Enzymes (Varies)
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9
Q
  1. What are the glands involved in the creation of Saliva
  2. How much saliva does a Cow and a Sheep make in a day?
A
  1. Parotid, Mandibular, Lingual & Sublingual, Buccal
  2. Cow 75-100L per day
  3. Sheep 6-16 L/day
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10
Q

What is Rumination?

A

Rumination is a reflex mechanism consisting of regurgitation of a “bolus” of rumen digesta

Rumination is a superimposed on the cyclic contractions of the rumen.

The need for regurgitation depends on the diet - coarser and less digestible fibrous diets cause an increase

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11
Q
  1. What is the pH of the rumen?
  2. Is in Anaerobic or Aerobic
  3. How is the contents mixed?
  4. What is the Temperature inside the rumen?
A
  1. 5.8-6.7pH
  2. Anaerobic
  3. Rumen contractions/regurgitation
  4. 39-41 degrees celcius
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12
Q

What are the two structural Carbohydrates?

A

Cellulose

Hemi-cellulose

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13
Q

Cellulose is a Beta-Linked Polysaccharides what is insoluble fibre.

  1. Describe the polysaccharide chains of Beta-1,4
  2. What are these chains linked with
  3. Cellulose is degraded by which enzyme to cellobiose (Beta-1,4 glu-glu disaccharide), then by which enzyme to 2 x glucose monosaccharides?
A
  1. Long Unbranche3d polysaccharide chaingt
  2. Linked glucose units
  3. Cellulase, Cellobiase
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14
Q

Hemicellulose is the other Beta linkied Polysaccharide

  1. Is it more or less soluble than cellulose?
  2. Describe the chains
  3. What is it linked with?
  4. Hemicellulose is degraded by What enzyme to xylobiose, which is in turn degraded by which enzyme to xylose?
A
  1. More Soluble
  2. Mostly linear chains
  3. Linked with xylose units
  4. Hemicellulase and Xylosidase
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15
Q

What is Pectin?

A
  • Pectin is a soluble fibre,
  • complex group of polysaccharides,
  • Act’s as a glue for cellulose and hemicellulose
  • Helps to bind cells together
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16
Q

Lignin

  1. Is Lignin a carbohydrate?
A

No its not a carbohydrate, it is a bit like cement, as it cements the cellouse fibres together, developes and increases as plant material gets older and more woody, Indigestible (except by some fungi)

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17
Q
  • What are storage carbohydrates?
  • What are the 2 alpha linked Polysaccharides (starchs)?
  • Which one of these two is more easily degraded and by what?
A
  • Cereals, eg Wheat, Barley, Oats
  • Amylose & Amylopectin
  • Amylopectin, is more easily and rapidly degraded, Bioth starches are beoken down by Amylolytic rumen bacteria
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18
Q

The Rumen Microbial Population is made up of 3 different things. What are they and what is the percent of the total biomass of each?

A
  • Bacteria ~50%
    • Bacteria carry out most of the fermentation of sugars, starch, fibre and protein in the rumen
  • Protozoa ~40%
    • Protozoa swallow and digest bacteria, starch, granules and some fibre
  • Fungi ~8%
    • Fungi make up only a small fraction of the rumen microbial population, but they appear to be important in splitting open plant fibres to make them more easily fermented by the bacteria
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19
Q

Describe the main purpose of Rumen fungi

A
  • Rumen Fungi are obligate anaerobes
  • They invade and colonise structural cellulose-LIGNIN components of plants breaking them up to allow bacteria to subsequently colonise the plant material
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20
Q

What is this?

A

Rumen Fungi

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21
Q
  1. What group is the main Rumen Protozoa group found within the Rumen?
  2. The numbers vary between season and diet.
    1. What diet would provide a high number of protozoa?
    2. What diet would you find a low number of Protozoa?
  3. Are the Anaerobic or Aerobic?
A
  1. Ciliates (hair-like organelles called cilia)
  2. Diet
    1. High amounts of Protozoa in starch (Grain) diets
    2. Low in Fibrous (Hay) diets
  3. Anaerobic
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22
Q

During Summer and Autumn would you expect Grazing Cattle to have a high or low amount of Rumen Protozoa?

A

Low

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23
Q

Rumen Protozoa : Ciliates

Are broken into 2 major groups they are :-

  • Holotrichs
  • Entodiniomorphs
  1. Explain what kind of substraight (diet) each of these are found
  2. What they ferment
  3. How to tell them apart under microscope
A
  1. Diet
    • Holotrichs are found on Fresh Pasture
    • Entodiniomorphs found in starch or fibre diets
  2. Ferment
    • Holotrichs are starch fermenters, sucrose, glucose, pectins
    • Entodiniomorphs - starch, hemicellulose, cellobiose
  3. See Picture
    • Holotrichs are entirely covered in cilia and have no spines or skeletal plates
    • Entodiniomorphs have reduced cilia, spines, and skeletal plates
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24
Q

Rumen Protozoa : Are the Good or Bad?

A
  • Good
    • Can ferment a wide variety of substrates so provide VFA for animal
    • Consume starch granules and tend to slow starch fermentation and stop acidosis
  • Bad
    • Not a lot pass down to the abomasum
    • means the animal cannot use the bugs that remain in the protozoa trapped in the rumen
    • Maybe they waste energy in the rumen?
25
Q

What are the 4 categories or Rumen Bacteria and what are their substrates?

A
  • Celluloytic - Cellulose
  • Saccharolytic - Hemicellulose
  • Amylolytic - Starch
  • Methanogens - Methane
26
Q

What of these are Alpha Linked Or Beta Linked polysaccharides?

A
  • Cellulose, Hemicellulose = Beta Linked Polysaccharides - Structural Carbohydrates
  • Starch - Alpha Linked Polysaccharides - Storage Carbihydrates
27
Q

Name the Rumen Microbes which relate to thes Carbohydrate Substrates :-

  • Cellulose
  • Hemicellulose
  • Other Fibres = Pectins, non starch polysaccharides
  • Starch
  • Sugars
A
28
Q

What are the major products from Carbohydrate Fermentation?

A
  • More Rumen microbes
  • Volatile Fatty Acids
    • Acetate (C2)
    • Propionate (C3)
    • Butyrate (C4)
  • CH4 (Methane)
  • CO2
29
Q
  • What are the 2 electron sink products in the Rumen?
  • What does an electron sink product do?
A
  • Rumen Electron Sink Products
    • Propionate
    • Methane
  • Electron Sink products allow glycolysis to continue anaerobically (NADH –> NAD)
30
Q

Outline via a diagram a summary of Rumen Carbohydrate Fermentation

A
31
Q
  • What is the Electron Sink product that Cellulolytic Bacteria relys on?
  • What is the Electron sink product that Amylolytic (Starch) bacteria uses?
A
  • Celluloytic Bacteria uses Methane as its electron sink Product
  • Amylolytic (Starch) Bacteria favours Propionate as its Electron Sink product however it can use Lactate
32
Q

Explain this graph

A

With High Cellulose (Hay diet) more acetic acid is produced and little propionic acid

As the diet becomes more Starch based the amylolytic bacteria produces more Propionic Acid (and less acetic acid) dropping the pH. As the pH drops then Lactic Acid Producer start to produce Lactic Acid causing rumen Acidosis

33
Q
  1. What are the products, produced by Cellulolytic Bacteria?
  2. What is its Electron Sink Product?
  3. Why is it essential to have the produced Hydrogen to be removed?
A
  1. Acetic Acid and H2
  2. Methane
  3. If Hydrogen is not removed (electron sink with CH4) the hydrogen inhibits the end product and therefore inhibits the breakdown of cellulose
34
Q
  1. Where are the amino acids absorbed in a ruminant?
  2. There are two sources of Amino Acids which are absorbed in this location, what are these sources?
A
  1. Small Intestine
  2. Amino Acids from
    1. Microbial Proteins
    2. Undegraded dietary true protein
35
Q
  1. What is Non protein nitrogen and what is its role?
A
  1. Urea and other sources of nitrogen are converted to ammonia, this ammonia can then be used to form microbial protein
36
Q

How is Nitrogen recycled within a ruminant?

A

Nitrogen is recycled via urea :-

  • Urea is formed in the liver, and is taken up by the salivary glands and secreted by these along with saliva.
  • The urea then helps contribute to microbial protein
37
Q

What happens if you supplement too much Urea?

A

too much urea can lead to ammonia toxicity

38
Q

Explain via a diagram Rumen Metabolism of Non Protein Nitrogen and Soluble & Insoluble Proteins

A
39
Q

When during a cows life cycle would it need the most Nitrogen

A
40
Q

What is the recommended maximum % of fats in a Ruminant Diet?

And why?

A

7ish % is the recommended Max

Fat is converted into NEFA which cna inhibit/kill the microbes

41
Q
  • Growing forage contains glycolipids which is what Omega Fatty Acids?
  • Oils or Oil Seeds contain tricylglycerol which are mainly what Omega Fatty Acids?
A
  1. N-3
  2. N-6
42
Q

Describe Fat Digestion in the rumen. (What happens to fats?)

A
  • Dietary fats (Phospholipids, glycolipids, triglycerides) undergo Microbial Lipolysis
  • Lipolysis release NEFA (can be toxic to microbes if too high) Unsaturated Fatty Acids (eg n-6 Linoleic acid C18:2, n-3 Linolenic acid C18:3)
  • Undergoes Biohydrogenation
  • transforming the Unsaturated Fatty Acids to Saturated FA’s C16:0 C18:0
43
Q
  • What is Biohydrogenation?
  • If you add unsaturated fats to the diet of a ruminant what effect may it have.
A
  • Its a Microbial activity which takes unsaturated fats and turns them into saturated fats. It does this by breaking the double bonds C=C which acts as an electron sink product and is converted into the single bond C-C
  • Unsaturated fats added to the diet of a rumeniant can reduce methane production
44
Q

When would you feed fat to ruminants?

A
  • During Lactation - Espcially high yielding dairy cows as fats are rich source of energy
  • Will help cows have a +ve energy balance
  • During Heat Stress
45
Q

What else does the Rumen Bacteria supply the animal Host?

A
  • Water soluble vitamins (not lipid soluble one - except for Vitamin K)
  • Some compounds de-toxified
    • Nitrate
    • Nitrite
    • Oxalates
    • Some alkaloids
    • Some mycotoxins
  • VFA
  • More Microbes
46
Q
  1. Whats are the two types of concentrates?
  2. What is the difference between these two?
A
  1. Cereal Grains, Legume Grains
  2. Difference
    1. Cereal Grains are high in Starch and low in protein. YOu typically need to feed a protein supplement, as High starch must be fed carefully to prevent rumen acidosis
    2. Legume Grains are high in protein and usually low in starch, Usually fed in association with cereal grains as legumes are expensive, Safer then cereal as low starch!
47
Q

Volatile Fatty Acids

  1. What are the 3 that are available in the Rumen?
  2. What is their fate?
A
  • Acetate
    • ​ Oxidised in aerobic tissues to produce ATP
    • Key substrate for lipogenesis when in excess of basil energy requirements
  • Propionate
    • Almost completely removed from Portal blood by the Liver
    • Within the liver Propionate serves as a major substrate for gluconeogenesis which is absolutely critical to the ruminant because almost no glucose/starch reaches the small intestine for absorption especially on roughage diets
    • Vit B12 - Cobolt MUST be in the diet for Propionate to be transformed into Glucose. Gluconeogenesis Does not work without it
  • Butyrate
    • Converted into keytone body D-3-hydroxybutyruc acid in the rumen wall.
    • Stimulates the growth of rumen epithelium
48
Q

Sturcture of Connective Tissue

  1. Made by cells - 3 types
  2. Matrix
A
  1. Made by cells
    • Fibroblasts
    • adipocytes
    • macrophages
  2. Matrix - Protein fibres
    • Collagen
    • Elastin
    • Ground substance (GLUE)
      • Proteoglycan
49
Q

An animal with a deficiency in Copper would have what problems?

A

It would not be able to make collagen and therefor their connective tissue would be weak.

Lysyl Oxidase (extracellular enzyme containing copper) which creates cross linking

50
Q

Name the 4 types of Collagen and what tissues they are found in.

A
51
Q

Describe the arrangement of Protein fibres in the following

  1. Tendon
  2. Skin
  3. Cornea
  4. Gelatine
A
52
Q

What is the cement in bone?

A

Hydroxyapatite

53
Q

ATP breaks actin/myosin linkages,

What is it called if you have no ATP to break these linkages?

A

Rigor mortis

54
Q

What are the 3 layers of connective tissue called?

A
  • Endomysium
  • Perimysium
  • Epimysium
55
Q

List the 3 types of Muscle fibres, Their twitch speed, and if they are areobic or anaerobic. Their myoblobin level and amount of mitochondria

A
56
Q

Inside the stomach of a human there is Hydrocloric Acid.

  • What cells secrete this?
  • Name the 4 functions of this?
A
57
Q

What are the 2 major digestive enzymes of the stomach?

A
58
Q

Pepsin is secreted by which cells?

A
59
Q

How is protein digested in the small intestine?

A

VET272 (3 decks)

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