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ANS 319 Animal Nutrition > Lecture 12- Protein Ruminant Digestion and Metabolism > Flashcards

Lecture 12- Protein Ruminant Digestion and Metabolism Flashcards

1
Q

What’s unique about ruminant protein digestion ?

A

Unique b/c ruminants can subsist and produce on a very low (sometimes almost zero) protein diet
– Microbial protein synthesis

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2
Q

What’s the biological value of ruminant protein digestion ?

A

Biological value= 70-90%
– AA profile resembles almost exactly what host requires

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3
Q

What’s the primary goal of protein digestion in the rumen?

A

Primary goal is to maximize microbial growth
– Microbes are a high value feed (meaning their
composition (essential amino acid profile) closely
resembles the composition of tissue and milk
* The cows small intestine then digests the microbes and this
releases an almost perfect blend of amino acids

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4
Q

Is there proteases in saliva of Rumen?

A

No

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5
Q

In the rumen is there any proteolytic secretions?

A

No rumen proteolytic secretions

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6
Q

What are microorganisms responsible for?

A

Microorganisms responsible for protein
digestion in rumen (and reticulum)
– Bacteria
– Protozoa

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7
Q

What are two sources of rumen nitrogen ?

A

-Feed
-Endogenous (recycles) N

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8
Q

What type of protein does rumens feed have?

A

– Protein nitrogen
Protein supplements (Soy BM, Cotton SM, grains,
forages, silages…
– Nonprotein nitrogen (NPN)
Usually means urea

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9
Q

What does endogenous (recycled) N contain?

A

-Saliva
-Rumen wall

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10
Q

Protein in the ruminant diet…what type of protein does the ruminant diet have?

A

**Dietary protein – contains amino acids
* Rumen Degradable Protein (RDP) – digestible “available to” by rumen microbes
* Rumen Undegradable Protein (RUP) – “escapes” rumen
digestion; enters small intestine unaltered
(Varies with diet, feed processing)
**Dietary non-protein nitrogen (NPN) – not “true”
protein…non-amino acid nitrogen; provides a source of nitrogen for microbial protein synthesis (Relatively CHEAP decreases cost of protein supplementation)

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11
Q

Types of Rumen Protein:

A
  • Rumen Degradable Protein (RDP)
    – Protein that gets metabolised (digested) in the
    rumen
  • Rumen Undegradable Protein (RUP)
    – “Bypasses” or “escapes” the rumen and
    hopefully is digested and absorbed in the
    small intestine
    – Protein not digested in the rumen
  • If not digested in the small intestine then it enters
    the large intestine and is thus unavailable to the
    ruminant animal.
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12
Q

What type of protein is Rumen Degradable Protein?

A

– Protein that gets metabolised (digested) in the rumen

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13
Q

What type of protein is Rumen Undegradable Protein (RUP)

A

– “Bypasses” or “escapes” the rumen and
hopefully is digested and absorbed in the
small intestine
– Protein not digested in the rumen
* If not digested in the small intestine then it enters the large intestine and is thus unavailable to the ruminant animal.

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14
Q

List the two types of dietary protein:

A
  • Rumen Degradable Protein (RDP) – digestible “available to” by rumen microbes
  • Rumen Undegradable Protein (RUP) – “escapes” rumen digestion; enters small intestine unaltered
    (Varies with diet, feed processing)
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15
Q

What is the process of protein degradation in the rumen?

A

Feed proteins…also known as -Undegraded feed proteins, escaped feed proteins, by pass proteins. and broken down into > peptides >amino acids

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16
Q

What are enzymes from protozoa and bacteria involved in when it comes to protein degradation in the rumen?

A

Enzymes from protozoa and bacteria
Many species of bacteria involved
Bacterial enzymes are extracellular
Both exopeptidase and endopeptidase activity

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17
Q

What does the protein in the rumen feed first?

A

**Feed the rumen microbes first (i.e. RDP)

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18
Q

What are the two counteractive processes in the rumen?

A
  • Degradation of dietary protein
  • Synthesis of microbial protein
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19
Q

What happens to some proteins in the rumen?

A

Some feeds proteins “escape” fermentation hopefully meet the remainder of animal’s protein requirements
(Escape protein, bypass protein, or rumen
undegradable protein) (RUP)
* Heat treatment

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20
Q

List factors that effect ruminal protein degradation:

A

*Chemical bonding
-Disulphide bonds – Reduces degradation
*Physical barriers
-Cell walls of plants (“embedded” within lignin)
-Cross linking of peptide chains – Reduces degradation
*Feed intake
-Rate of passage – Time proteins spend in the rumen
*Feed processing
-Rate of passage
-Heat damage – Complexes with carbohydrates

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21
Q

What is dietary proteins classified based on?

A

Solubility in the rumen . Into fractions

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22
Q

List the fractions of protein:

A

Fractions:
– A
NPN, instantly solubilized/degraded
– B
Potentially degradable
(Depends upon amount of time spent in rumen)
– C
Insoluble, recovered in ADF, undegradable

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23
Q

What does degradation depend on ?

A

depends upon both the nature of the protein and the length of time it remains in the rumen. As feed intake and passage rate through the rumen increase, retention time in the rumen and degradation decrease

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24
Q

What does rumen degradability estimate?

A

It estimates for the crude protein in common feed ingredients

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25
Q

What does deaminate mean

A

when you have an amino acid and an amino group, the bond between in acid and the amino group is hydrolysed (no longer attached) the bug them ferments the amino acid into VFA’s and ATP. and there is also an ammonia molecule that creates threonine

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26
Q

What are proteins broken down into in the rumen?

A

Peptides and amino acids

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27
Q

All the enzymes in the rumen? how are they made?

A

By the microbes

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28
Q

What does the rumen microbes digest/use/metabolize?

A

Dietary protein

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29
Q

What does rumen microbes create differences between ?

A

Protein quality in feed and protein actually absorbed by the host (different than in monogastric nutrition)

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30
Q

What does microbes break down dietary protein into?

A

-Amino acids
-NH3, VFA’s and CO2

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31
Q

What does microbes re-synthesize?

A

Amino acids (including all the essential amino acids from NH3 and carbon skeletons)

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32
Q

Is there absorption of protein or amino acids from rumen?

A

-No absorption (Or from cecum or large intestine)

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33
Q

Is urea digestible?

A

Urea is almost 100% digestible

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34
Q

Does microbial protein have a high biological value?

A

Yes it has a high biological value because its amino acid composition very closely matches the amino acid requirement of muscle and milk.

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35
Q

How much microbial protein can a dairy cow produce?

A

2.7kg (6lbs) of microbial protein a day.

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36
Q

What’s the 2 regulations of microbial protein?

A

1-Up regulation
2-Down regulation

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37
Q

What’s up regulation like?

A

Straw (low quality protein) gets turned into microbial protein (high quality)

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38
Q

Whats down regulation like?

A

Egg protein (very high quality), gets turned into microbial protein.

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39
Q

Whats microbial protein synthesis related to?

A

1- Available NH3 and amino acids (DIP)
2- Fermentation of CHO- Energy

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40
Q

When maximising microbial growth a.k.a. microbial protein synthesis:

A
  • Coordinate CHO fermentation patterns
    with protein degradation patterns.
  • The energy provided from fermentation
    (ATP generated during glycolysis) is
    captured to maximize microbial growth
41
Q

What is energy required for in the rumen?

A

Its required for rumen microbes to synthesize protein

42
Q

What are acids and ammonia produced from?

A

Produced from the breakdown of carbohydrates and crude protein and are used to make microbial protein

43
Q

What happens to access amino ?

A

Its excreted

44
Q

List the factors limiting Microbial Protein Synthesis:

A
  • Amount of energy
    – ATP
  • Available nitrogen
    – NPN
    – Degraded feed intake protein nitrogen (RDP)
  • Available carbohydrates
    – Carbon residues for backbone of new amino acid
45
Q

What does microbial crude protein synthesis rely on?

A

It relies on synchronization of carbohydrate (for carbon backbones) and nitrogen availability (for amino group)

46
Q

What can affect amino acid fermentation?

A

Rates of carbohydrate fermentation

47
Q

Slowly fermented CHO….

A
  • CHO fermentation for growth might
    lag behind PTN/AA fermentation
48
Q

Rapidly fermented CHO….

A
  • PTN/AA fermentation and CHO might be more closely matched
49
Q

What might offset some disruption in CHO and AA fermentations?

A

Recycling of N into the rumen

50
Q

Whats the craic with Nitrogen recycling?

A

Its unique to ruminants

51
Q

List the 3 fates of Rumen Ammonia?

A
  1. Bacterial protein synthesis
  2. Absorbed from reticulorumen and omasum NH3 passes from rumen by diffusion into portal blood. (High concentration to low) Utilized in the liver to make urea…the urea cycle
  3. At healthy rumen pH, little NH 3 lost as gas
52
Q

Whats the process of overflow ammonia?

A
  • Shortage of energy relative to available NH 3
  • Liver: NH 3 > Urea
  • Urea “recycled” or excreted (urine),
    depending on animal needs.
    – Recycled back into the rumen via
    (Saliva ,Rumen wall)
53
Q

Explain the fate of absorbed ammonia:

A
  1. Transported to liver by portal vein
  2. Converted to urea via urea cycle in liver
  3. Urea released into blood, Dumped into urine, or recycled back into rumen
  4. If capacity of urea cycle in liver is exceeded, Ammonia toxicity can occur
    Happens during over consumption of urea
54
Q

List facts of Nitrogen being recycled to the rumen for reutilization:

A

– Ability to survive on low nitrogen diets
– Up to 90% of plasma urea CAN be recycled to rumen on low protein diet
– Over 75% of plasma urea will be excreted on high protein diet

55
Q

What happens to plasma urea that enters the rumen?

A

-Saliva
-Diffuses through rumen wall from blood

56
Q

What converts urea into ammonia + CO2?

A

Urease

57
Q

Name the 2 proteins that leave the rumen?

A

1- Microbal protein (MCP)
2- Rumen Undegradable Protein (RUP)
Escape protein (aka “bypass” protein)

58
Q

When the proteins leave the rumen, where does it enter or go to?

A
  • Both enter abomasum & small intestine
    – Digested by proteolytic enzymes similar to nonruminants
59
Q

Whats the definition of “bypass” proteins?

A

Proteins that aren’t extensively degraded in the rumen

60
Q

List natural “bypass proteins”

A

Corn proteins, blood proteins, feather meal

61
Q

Whats the modification of feed proteins to make them less degradable ?

A

*Heat- Browning or Maillard reaction. Expeller SBM, Dried DGS, Blood meal.
*Chemical- Alcohol + heat

62
Q

What is there usually some loss in?

A

Availability of amino acids- lysine.

63
Q

Whats a maillard reaction definition? and give eg.

A

Non-enzymatic browning
-Steak on a pan
-Flame browning

64
Q

Definition for Non-protein Nitrogen?

A

Nonprotein nitrogen (NPN) compounds contain N, but are not composed of amino acids.

65
Q

Name organic NPN:

A

Organic NPN compounds include ammonia and urea.

66
Q

Name inorganic NPN:

A

Inorganic NPN compounds include a variety of salts, such as ammonia chloride, ammonia phosphates, and ammonia sulfate.

67
Q

Whats the least costly source of NPN:

A

Urea, which accounts for the tremendous interest in its use in feeds for ruminants

68
Q

Whats the limitations of non protein nitrogen on urea usage? (3)

A
  • Urea can only be used as a source of N for ruminant animals when there is an adequate supply of readily fermentable carbohydrates.
    – Urea is not a satisfactory source of N for animals fed primarily on poor-quality roughage.
    – Urea is not a safe source of N for monogastric
69
Q

Is urea a safe source of N for monogastric?

A

Urea is not a safe source of N for monogastric

70
Q

Whats urea converted into?

A

2 Ammonia (NH3)
Carbon dioxide (CO2)

71
Q

Whats an activity associated with microorganisms?

A

*Degradation of NPN
Urea is converted to CO2 + 2 NH3

72
Q

what should be matched ?

A

Protein and energy source, in order to maximise microbial growth

73
Q

Exam Question - Whats the biochemical phenomenon that lets rumens survive on a low protein diet.

A

Animal absorbs N in rumen, access N in rumen, end product of too much N coming in = ammonia. (Explain how ammonia is made) Ammonia is taken up by the rumen wall and travels to the liver, No animal likes ammonia its toxic it will kill you. A monogastric converts Ammonia to Urea and dumps it into its bladder and excretes it out OR it also goes into saliva or rumen as simple diffusion. The stuff that’s in saliva(urea) gets swallowed and goes back inside the rumen. Urea can be broken up by an enzyme the microbes in rumen called urease.

74
Q

Do you feed urea to monogastrics?

A

NO -
just ruminants you don’t feed it to monogastrics. You feed it to ruminants because its dirt cheep. The bugs don’t care how the animal gets the nitrogen. Farmers will feed cheap urea to maximise farm activity, In most areas urea will be the least cost of nitrogen

75
Q

What’s the enzyme that it made by the microbes that breaks down urea?

A

Urease

76
Q

What is urea rapidly degraded to in the rumen?

A

Rapidly regraded into ammonia

77
Q

Whats the “fate of the blood urea”

A

1- Excreted into urine
2- Taken up into milk(if lactating)
3- Recycles to digestive tract via Blood saliva OR Diffused into GIT and across rumen wall

78
Q

Do you use urea with a low quality forage/carbohydrates

A

NO because its very SLOW digestible

79
Q

How do you prevent Urea(Ammonia) Toxicity?

A

– Mix feeds well
– Don’t switch rapidly from natural protein to urea
– Always have feed available
– Don’t allow hungry animals access to highly palatable, high urea diet, feed, or supplement (including lick tanks)
– Don’t use urea with low-energy feeds

80
Q

When was urea(ammonia)toxicity first discovered?

A

first discovered in urine in
1727 by a Dutch scientist

81
Q

List signs of toxicity:

A

– Appear 20-30 min after urea ingestion
– Rapid and labored breathing
– Tremors
– Poor coordination
– Inability to stand & tetany increasingly
apparent

82
Q

Whats urea toxicity treatment?

A

– Orally dose with 5% acetic acid
* Shift equilibrium from NH 3 to NH4+
* Increased rate of absorption

OR
-Drench with cold water
*Decrease rumen temp. which decreases rate of urea hydrolysis.
* Dilutes NH 3 concentration
* Takes 6-12 gal.; not practical when several sick

83
Q

SLIDE 55 LEARN IT OFF

A
84
Q

Summary- What do microbes break down feed proteins into? Does this require much energy? What is it important to match?

A

Amino Acids and reincorporate them into microbial protein
Required ALOT of energy
Important to match fermentation patterns of CHO’S and protein.

85
Q

Wen excess NH3 (Urea/Ammonia) is produced in the rumen what happens to it?

A
  • Excess NH3 produced in rumen can be
    taken up by rumen and converted to urea
    in the liver
  • The urea is then recycle back to the rumen
    and rumen bugs convert urea back into
    NH3
  • The bugs then can incorporate NH3 into
    microbial protein
86
Q

What’s Similar with Ruminant vs Non ruminants?

A
  1. A t tissue level – Metabolic pathways similar
  2. Ruminant tissues can synthesize non-essential AA
  3. Cannot synthesize essential AA – Essential AA must be provided from digestive tract
  4. Tissue proteins constantly undergoing turnover
  5. AA not stored
  6. Constant supply of AA required
87
Q

What are dissimilarities in ruminants vs nonruminants ?

A
  1. Microbial population has profound effect on AA reaching S.I.
    a. AA profile at S.I. different from diet
    * Up-grades low quality dietary protein
    * Down-grades high quality dietary protein
    b. Enables ruminants to use NPN efficiently
    * Ruminants can be productive without a source of dietary true protein
    c. Animal can survive on low amounts of dietary protein by recycling N (as urea) back to rumen
88
Q

Whats the relation between protein protein intake and performance?

A

Optimal rates of tissue protein
synthesis require:
- adequate total quantity of amino
acids
- mixture of amino acids that
matches the composition of the
proteins being synthesized

89
Q

Is protein cheep or expensive?

A

Its EXPENSIVE
* The protein content of a food/feed in large part dictates its price
* This is similar to animal, companion and human nutrition
* The protein content of a food/feed is determined by its nitrogen content.
– Laboratory assessment of Nitrogen. Calculate [protein]
* The nitrogen is assumed to have come from a protein

90
Q

How do you assess how much Nitrogen is in a feed?

A

In a laboratory assessment of nitrogen you calculate Protein.

91
Q

What’s is Melamine used as an ingredient in?

A
  • Used as an ingredient in many common
    household items, including cleaning
    products, plastics, fertilizers and glues.
92
Q

How much nitrogen molecules are in melamine?

A

6 Nitrogen Molecules
– 66% nitrogen by mass
– Typical protein has ~10%

93
Q

List current uses of Melamine:

A

*Dry erase boards
*Counter tops
*Dishes
*Fertilizers

94
Q

What was melamine added as a protein supplemental in what diets?

A

Added to foods/products to
falsely increase the crude
protein content

95
Q

Where were high levels of melamine found in ?

A

Found in pet food and milk products in China
* Deliberately added to products and
ingredients to falsely increase nitrogen
levels:
– so milk of poor quality passes protein test
– Increases ingredient value

96
Q

What is Melamine toxic to ?

A

Toxic when its fed to animals and humans

97
Q

Why is Melamine so bad for you?

A
  • Melamine forms crystals in the kidney and
    can cause renal failure in humans and
    animals
  • 2007 Hundreds of pet deaths (USA)
  • 2009 several infant deaths in China
98
Q

What was the Melamine Scandal?

A
  • September 11, 2008 infant formula recall
    in China
  • 22 other companies had contaminated
    milk
  • ~300,000 ill infants
  • ~ 52,000 hospitalized
  • 6 children died
99
Q

Whats important to know about dipeptidases?

A

Cleaves Dipeptides

ANS 319 Animal Nutrition (17 decks)

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