Protein in Ruminants Flashcards
1
Q
what are the major roles of rumen microorganisms
A
- fermentation of diatary carbohydrates (yeilds atp for bacterial growth, VFAs as a waste product)
- breakdown of dietary nitrogenous compounds
2
Q
where do nitrogenous compounds come from in feeds and what type of feeds
A
- true proteins - EAA, NEAA linked by peptide bonds
- canola meal, soybean meal and fish meal
3
Q
what kind of nitrogenous compounds are in feeds
A
- NPN
- Urea
- Ammonia
- free amino acids, small pepetides, nucleic acid
4
Q
what is NPN
A
- non protein nitrogen
- or protein not associated with protein
5
Q
what is Urea
A
- the most common form of NPN
- up to 2% in beef cattle rations
6
Q
where does ammonia, free AA small peptides and nucleic acids
A
- fermented forages
7
Q
what utilizes ammonia
A
- bacteria can used ammonia as a protein source for protein synthesis
- protozoa dont have enzymes to use ammonia for protein synthesis (they engulf bacteria themselves)
8
Q
what determines the perfeered N source
A
depends on bacterial species
- fiber digestors = fibrolytic and cellulolytic prefer an ammonia N source
- starch digesters = amylolytic prefer AA and peptides as preferred nitrogen source
9
Q
how does ATP influence N
A
- coupled fermentation or nutrient synchronization
- nitrogenous compounds available at the same time as energy needed to drive protein synthesis
10
Q
why maximize ruminal MP production
A
- microbial protein is the most important source of AA in ruminants
- most of the AA is absorbed in the small intestine
- MP is a high quality, cheap protein for ruminant, high in lysine and methionine
11
Q
what factors can effect rumen MP production
A
- available energy ( Fro, ATP and fermentable carbs)
- rumen ammonia levels
- synchronization of fermentation (coupled fermentation)
- preformed amino acids and peptides
- other nutrients (sulfure and phosphorus)
- rumen environment
12
Q
what are the major factors of rumen ammonia concentration
A
- time post-feeding (once fed fermentation occurs, ammonia goes up, reaches peak and then goes down till next meal)
- frequency of feeding (the more fed, the more stable the rumen ammonia concentration
- protein/ ammonia source ( fish meal - slowly degraded conola meal - quickly degraded) fermented forages - high ammonia conce rises rapidly
- energy availability
13
Q
what is rumen dilution rate
A
proportion of total volume leaving the rumen
- fluid, particular passage 2-20% per hour - liquid phase flows out much faster
- rumen microbes leave with both the solid and fluid phases - when they leave faster, more microbes reach the small intestine
14
Q
the faster dilution rate, the greater the rate of outflow of microbial protein. What is the reason for this?
A
- if bacteria flow out faster, the protozoa cant consume then less
- less bacteria are used to sustain them as nutrients
- faster dilation rate is more is a more efficient way of achieving microbial protein
15
Q
what is the role of protozoa in overall rumen balance
A
- dont need them, protein metabolism would be more effective without them
- 20-70% of rumen microbial biomass
- 10-40% of total tumen nitrogen
- only 20-40% washout to lower gut - only minor contribution to metabolizable protein
16
Q
what happens to extensive ammonia production in the rumen
A
- wastage
17
Q
what happens to microbial eyild with predation of ruminal bacteria
A
- reduces microbial yeild
18
Q
what does defaunation do to rumen N efficiency
A
- reduces rumen protein degration
- reduces rumen ammonia concentration, N waste
- increases rumen bacterial protein yield
19
Q
what factors influence extent of rumen degration
A
- protein structure - type of protein
- rumen passage rate
- rumen pH and diet type
20
Q
how does protein structure influence extent of remen degration
A
- significant influence on protein degradation = bacterial enzyme access
- protein denaturation = HCL in the stomach uncoils protein accesible to enzymes
- hydrogen bonding disulfide linkages = decrease them to increase solubility
21
Q
how does feed particle size influence rumen degration
A
- the larger the particle the more degradable it is
it increases the surface area the increase of digestion
22
Q
how does rumen pH and diet type influence rumen degration
A
- optimal pH for proteases is 5-7
- acidosis on high grain diets - protein digestion decreases
- predominant microbial population - proteolytic, cellulolytic bacterial activity decreases
23
Q
how can you manipulate protein degration in rumen
A
- lower protein degration - lower ammonia production in rumen , increase by-pass protein
- physical methods - heating or roasting (protein denatured, solubility decreased, decreased degration)
- alters protein structure, solubility, denaturation, cross-linkages of proteins, carbs
- chemical treatment
- cross-linkages between proteins, chemicals(less soluablity lower degration of protein goes down)
- cross-linkages broken -down in acidic conditions - protein available
- ## hazardous
24
Q
What do you need to be careful of with manipulation protein degration
A
- satisfy microbial N requirements - need to make sure of it = rumen degradable protein
- requirement for by pass protein - high producing ruminants - make sure they require RUP
- do not over protect protein - by producing feeds, to make sure RUP is digested in small intestine
25
how are AA protected from rumen degration
- surface coating with a fatty acid/pH sensitive polymer mixture
- most effective
- pH differences between rumen, abomasum
- high protection, intestinal digestibility
26
what are the different ways are ammonia absorbed
- passive diffusion (uncharged easily passes through)
- potassium channels (need for charged ammonia diffusion)
27
what three major factors of ammonia absorption
- rumen ammonia levels = loads of ammonia in rumen, absorbed in blood
- ATP supply - ammonia goes down, microbes can use ammonia to synthesize microbial protein
- rumen pH - more alkaline ph, more absorbtion
28
what is the fate of absorbed ammonia
- transported to liver by portal vein
- converted to urea via urea cycle in liver
- urea released into blood
- excreted into urine milk
- recycled into digestive tract ( salvage mechanism to)
29
what are the mechanisms for urea recycling
- 15-20% via salivia, coming from blood streams (the more in teh bloodstream more in salivia )
- urea increases in salivia, more chewing, more mastication adn more salivia
- direct tranfer across rumen wall
30
steps in direct transfer across rumen wall
1. urea transporter expresed in rumen wall, transports urea from blood to rumen, no ATP required transport protein
2. aqua porin - co transports water and urea
3. maintainance of urea concentration. blood concentration higher then rumen because urea degraded quickly in rumen
4.if atpnot available, ammonia absorbed in blood or recycled to rumen
31
factors affecting urea recycling
- dietary N/CP levels = high N lower liver urea recycling
- intra-rumen ammonia - activity of ureolytic bacteria (more protein in diet, more ammonia in rumen )
- blood urea - urea secretion in rumen
- increasing dietary rapidly fermentable carbs, goes down and urea secretion goes up
32
how does urea recycle in the lower GIT
large intestine = urea diffusion from blood (urea can enter all systems of GI tract)
33
what do resistant starch or high fibre diets do to urea recycling
- creates resistance to fermentation in rumen, digestion in small intestine and more fibre reaches the small intestine
34
microbial protein production with no nutritional value
- post small intestine no digestion capability, poses through unaffected
- only protein from rumen will be digested
35
what is the significance of urea recycling
- source of N for microbes when N consumption is limited
- over-wintering cows or wild ruminants (low N intakes; infrequent feeding of supplemental protein)
- slowly degraded fee proteins (recycling provides N for microbial growth - reduced ammonia concentration
36
what are advantages of rumen protein degration
- rumen microorganisms supply a high quality protein
- recapture of endogenous urea N for microbial protein production (urea recycling)
37
what are disadvantages of rumen protein degration
- rumen microbes highly proteolytic (high quality dietary protein wasted , will continue degrading protein)
- most dietary N absorbed as amonia nitrogen (needs to absorbed as amino acids most efficient use, in ruminants aa absorbed as ammonia cant be used as building blocks)
38
what are similarities in ruminants and non ruminants
- require a source of essential amino acids (lysine, methionine usually limiting for protein synthesis
- inadequate body synthesis
- can synthesize non essential Amino acids ( intestinal absorbtionand de novo synthesis in the body)
- in both groups amino acid absorption in small intestine
39
what are the differences ruminants and non ruminants
- ruminants = dietary protein quality not as critical as with non ruminants, presence of bacteria, protozoa in rumen makes marked changes in diet protein
- source of AA for absorbtion different (diet VS microbial protein, RUP)
- protein, AA needs - for non ruminants, consider the AA needs of the animals, for ruminants consider protein (N) needs of bacteria and protozoa; then consider protein, AA needs of host animal)
- ruminants can use NPN(urea, ammonia production from urea contributes to microbial protein production)
- ruminants can survive, produce milk, reproduce on NPN alone ]\
- nitrogen recycling in ruminants (urea produced in liver can be returned to rumen, protein deficiency)
- hind-gut recycling in monogatrics
