Nutrition lecture 8 - Ruminant protein nutrition
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Is there a full seperation between reticulum and rumen?
cow with an opening in a rumen tot he outside is said to be?
Why does the rumen have such a huge volume?
- Needs to be able to go slow and take time because it is a slow process
- If roughages have low nutrients need to consume more of it
Rumen and reticulum make up how much % of the GI in the ruminant?
Methane loss in the rumen can be a concern becaus eof?
Energy loss and greenhouse gas effects
Fermentation in the rumen is?
2 big ways to control rumen pH?
- Saliva buffer
- Absorbtion of volatile fatty acids
Why is it imperative that cows eructate?
To prevent distension and free u space
Are all bacteria in the rumen anaerobes?
- NO can be faculative anaerobes as well
- Important in saving rumen environment in fistulated environment
How many distinct phases of the rumen are there and what are they? Where does yesterdays and todays feed fit into this?
- Solid - todays feed
- Liquid - yesterdays feed
Contractions in rumen are good for?
Mixing seperate layers and moving gas to the from for eructation
3 classes of microorganisms int he rumen?
Bacterial enzymes in the rumen are intracellular or extracellular? Why?
- Extra Because a bacteria cannot engluf an entire piece of straw, the substrate is too big so has to eat it on the outside
- Becomes a problem because then other bacteria can get to it
Are there more bacteria or protozoa? How does this relationship change when it comes to biomass?
- WAyyyyyy more bacteria
- Same biomass
Most bacteria (75%) can be found where in the rumen?
Attached to feed particles
What are the bacteria attached to the rumen epithelium going to digest?
What are the 4 places we find bacteria in the rumen?
- On substrate
- free floating
- on rumen epithleium
- Attached to surface of protozoa
What are the bacteria on the protozoa surface doing?
- being methanogens
- probably pumping protein into the protozoa
What are 4 benefits of the bacteria attaching to substrate in the rumen?
- Brings enzymes and substrates together
- Protects enzymes from rumen proteases
- retention for prolonged digestiion
- reduces predatory activity of protozoa
The rumen ecosystem will depend strongly on?
THe diet they are receiving and how the bacterial populations change to his diet
2 major advantages of pregastric fermentation
- Make bettter use of fibrous roughage fibers
- can convert cheap non protein nitrogen into high quality microbial protein
What can bacteria do that we cannot in terms of digestions?
What happens to plants lignin as they get older?
Name 4 rumen carbs that are fermented? What are they all fermented to? Which is used by?
Where do ruminants get most of their energy?
Volatile fatty acids
Big gaseous loss of energy from fermentation?
In true protein the N is bound in? In non true protein it is?
- AMino acids
- Anything, urea, ammonia,etc
What is non protein nitrogen?
Protein not associated with amino acids
give 3 examples of non protein nitrogen?
The Kjeldahl method determines?
Nitrogen in the sample then we x by 6.25 which is the constant to get protein
Proteins on average contain how much nitrogen?
Can ruminants work on NPN alone?
Yes can even do work and production
Can todays dairy cows reach maximum production on NPN?
No not at all we have way to intens eof animals
Why would we want to feed urea rather than protein?
Is urea always palatable?
No often have to add mollasses
Why dont we feed dairy cows NPN?
Often high NPN in silage already adding more is getting a bit too high
What happens if you feed high urea and no fermentable carb like urea straw diet?
- Urea toxicity
- you need that carb
What are 4 guidelines to feeding urea?
- Supply adequate carbs
- Feed low for daily efficient utilization
- mix urea containing supplements thouroughly with other feed ingredients
- adequate supply of P and S
Why is it important togive an adequate supply of sulpher
Because some essential amino acids need sulfer not so much nitrogen or both
Is urea toxic? How does it cause urea toxicity?
- Ammonia is and it is toxic to the CNS
Can protozoa use ammonia from the bacteria?
No they cannot so to get protein N they have to snack on the microbes or have them make it for them
So can urea be converted DIRECTLY to microbial protein?
No it has to become ammonia first
What are the 3 Microbial requirements for growth?
Where can it get much of its N?
NH3 can be 18-100%
Are vitamins often a concern in the rumen?
No so so much is synthesized
While having both energy and N avalability are important for bacterial protein synthesis what is also a very important factr regrding this?
Timing, they both have to be present at the same time
So in terms of having N and having ATP we will optimize protein production when?
We have them both at high levels
How can we go about matching ATP anfd N in the diet for protein production?
Feeding a diet containing energy and protein ingredients
What are the 5 crude protein fractions and what do they represent?
- A - NPN, degraded
- B1 - soluble proteins
- Non solubles
- B2 - less soluble
- B3 - less soluble
- C - undigestible
An example of a C fraction of crude mprotein coyuld be?
A completely undigestible form of protein so for humans maybe fingernails
In terms of our protein fraction A-C what would represent the total crude protein? What about rumen degradable or degradable intake protein? What about rumen undegradable protein or undegradable intake protein?
- A fraction +B and C
- A+B fraction
- Certain fractions of B1, B2, and B3 that escape the rumen
What are the 4 fed carbhydrate fractions? explain each slightly
- A - sugars
- B1 - starches
- B2 - available cell wall
- C - unavailable cell wall
In carbohydrate fraction C we would be likely to find?
Lignin and the likes
Of the carb fractions which are simple and which are complex?
- A is simple
- B and C are complex
NDF is what constiuents? ADF?
- Cellulose, hemicellulose and lignin
- Cellulose and lignin
Why do we want a slow release of NPN and energy fron fermentable carbs? How do we get this?
- Cause it will be a sustained controlled release that wont spike or drop and cause a loss of homeostasis
- Match protein and energy sources different sources release at different points and in different ways and if we matcgh them we can get the most efficient production
Uncoupled carb fermentation and ammonia concentration leads to?
Inefficicent protein production
What makes up the matabolizable protein that gets to the animal?
- Bypass protein and microbial protein
- Maybe a bit of endogenous sloughed off protein
Is microbial protein a good source of protein?
Yes it is 80% digestible and has a great essential amino acid profile it very closely matches milk composition it is only beat by fishmeal which is wasteful expensive and excessive
2 most limiting amino acids in north america?
Lysine and methionine
Fish meal does what to milk?
IMparts a fishy taste
6 factors affecting rumen microbial protein production?
- Available energy
- Rumen NH3 levels
- Synchronization of fermentation
- preformed amino acids/peptides
- Other nutrients
- rumen environement
Is rumen NH3 concentration dynamic or static?
Very dynamic, it is always changing
Depends on what?
- Time post feeding
- Frequency of feeding
- Protein/NH3 source
- Energy availability
Rumen NH3 concentration is very dynamic, which means it is wasteful as it peaks and valleys, what can we do to try and limit these fluctuations and waste?
Feed more frequently
Obviously the rumen environment affects microbial growth, explain 2 ways this happens
- Proportion of total volume leaving the rumen/hour = faster outflow means reduced maintenance energy requirements, reduced protozoal predation and shorter generation time
- Acidic rumen conditions reduce microbial growth
Do all microbes leave the rumen in the liquid phase?
no many can leave on the solid phase
Faster rumen outflow means what for the age of the bacterial population?
Stronger younger population
How much % do protozoa make up of the microbial protein digested by the cow?
4 big positives from protozoa in the rumen? 3 negatives?
- Participate in cellulose digestion
- highly proteolytic
- slower fermentation of starch and sugars
- remove O2 from rumen environment
- Can reduce bacterial protein yield via predation
- increase CH4 production
- highly proteolytic
How do protozoa slow down carb fermentation?
How can being hihgly proteolytic be both a positive and negative in terms of the rumen?
- Can help contirbute to ammonia (cant use it)
- Can produce too much ammonia and can be toxic to the CNS
A higher ammonia concentration in the blood means what for wastage?
Increased wastage cause excreted in urine, want to avoid huge peaks or the ammonia ends up in the blood and being excreted out
What do we see with rumen defaunation (removal of protozoa)
- Increased daily gains and milk yield, increased total microbial protein flow in the small intestine less methane loss GOOD
- Decreased cellulose digestion, decreased pH cause no control over slowed down starch fermentation BAD
In this case the bad outweighs the good because we see better performance
What are 2 ways to defaunate a rumen for research purposes? What abotu practically?
- Chemicals toxic to protozoa
- Isolation of animals at birth
- Feed high concentrates
- Feeding unsaturated fatty acids
Do feedlot cattle have high protozoa?
No very low cause of high concentrate diet
What is defaunation?
Removal of protozoa from the rumen
Why do unsaturated fatty acids hurt protozoa?
Likely some sort of membrane disturbance
USing practical methods such as high grain diets and unstaurated fatty acids will you ever truly defaunate an animal?
No just lower
What is the benefit of providing bypass protein?
- Maximize the protien going to the animal
- Often dairy cows can keep protein production up
Does a non pregnant beef cow need bypass protein?
In terms of feed crude protein fractioons what do you want to do to increase bypass protein? How does contribution to bypass protein change as you go down from A to B3
- Change proportions of B1 and B2 and B3 to favor more passage
- The amount of bypass contribution increases as you go down this list
What can you do to byproducts or protein ingredients to cause an increase in bypass protein?
Heat to decrease availability to bacteria
3 factors affecting extent of rumen degradation?
- Protein structure
- Rumen passage rate
- Rumen pH and diet type
So a protein that has secondary and tertiary structure is more or less degradable? Does it do anything else to the protein? Explain?
- yes it decreases its solubility through the disulfide linkages
The higher degree a protein structure is folded or changed means a higher?
Drop in digestibility
Is animal or plant protein less degradable in the rumen?
Plant or animla protein is more palatable?
Can we feed bovine protein to bovines?
Rumen passage rate relates how to degradation?
They are inversely related
Rumen passage rate can vary with? (3)
- Particle size
- Fiber content
What will always be a cows main protein source?
Bacteria so still need to feed them
So the larger the particle size what do we see happen to digestibility?
Larger particle size means less digestible
What happens to the bacterial population and the predominant enzymes in the rumen when the pH drops?
- Proteolytic activity increases and
- cellulytic bacteria decrease
Most of B3 will pass already so for bypass you want to change?
B2 and B1
Heat treatment would do what to the rumens ability to degrade soybean meal?
Heating while making protein less available to the rumen microbes does what for availability to us?
Increases the availability to us
How can chemicals make proteins less digestible?
Causes cross linkages that make unavailable to bacteria and that are broke n down in an acidic environment
So so far wjat are 3 ways we can creat bypass proteins?
- chemically treating
- Cover in fatty acid polymer
Do we have any use for fraction c?
Can we over heat protein products?
Yes then we cause a maillaird reaction and the protein becomes unavailable to the animal as well
Explain covering proteins with fatty acid mixtures?
USually they are pH sensitive this gives them high protection and intestinal digestibility
Why dont we see dairies often using fatty acid protected proteins as bypass proteins? What about chemicals?
- Pretty expensive
- possibly toxic to the animal
Urea in blood can go 2 places?
Kidneys or saliva
IS ammonia absorbtion passive or active?
3 major factors affecting the rumens ability to absorb NH3
- Remun NH3 levels
- ATP supply
- Rumen pH
Elaborate on pH
a alkaline pH favors NH3 which is neutral and not charged so crosses the membrane easier
Ammonia is converted to urea where?
Is urea ever excreted into the milk?
Yes its called milk urea nitrogen
2 mechanisms for urea recylcing back into the rumen?
- direct transfer across the rumen wall
Why does a higher forage diet result in more urea recycling?
More chewing cud more slaiva more urea in the saliva
Is urea transported into the rumen passively or actively?
What happens to urea when it first makes it past the rumen wall and into the rumen from the blood?
- Broken down by ureolytic bacteria into ammonia
- This causes what???
A gradient of ammonia in rumen with more by the wall
In low N diets what do we see happen to the Urea in urine?
It decreases as it is reabsorbed to be used in the body
Do camels excrete urine?
Nope essentially nothing they are incredddddiiibbbllleee
Is nitrogen recylced in ruminant significant?
Yes largely could make up 15% of their protein requirement
So higher protein diets result in ____ urea recylcing while low protein diets result in ____ urea recycling
4 factors affecting urea recycling?
- Dietary N level
- Intra rumen NH3 (effects passive diffusion)
- Blood urea concentration
- increasing dietary rapidly fermentable carbs
Does hindgut microbial protein production get absorbed?
No your passed the absorbtive area already
How can urea recycling help animals wduring harsh times?
- Can provide a supplement during times of little or poor food
- ex) over wintering cows or wild ruminants
3 inputs of nitrogen in the rumen?
- Dietary protein
- Recylced urea
- Microbial protein turnover
Disadvantages of foregut fermentation?
- Ammonia toxicity
- energy loss from methane
- Nitrogen losses
- maintenance costs of bacteria
- high quality proteins dont mean anything at all
Describe rumen fungi?
- Few in the rumen, slow growing population with long turnover time
- role not well understood
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