Protein Metabolism RuminantsSubjects to be covered
• Digestion and metabolism in the rumen
• Protein requirements of ruminants Models
Define requirementsDescribe feeds
Optimize production
• Environmental issuesPrevent overfeeding nitrogen
Protein• Analysis: Determine total N by Kjeldahl
– All N NH4+
– Determine as NH3
– Total N x 6.25 = crude protein
• Peptide bond:
NH2
R1-C-C-NH O C-C=O
R2 N-C-COOHH R3
Nitrogenous Compounds in Feeds
• True proteins Polymers of amino acids (18 to 20 different
amino acids) linked by peptide bonds• Essential amino acids (nondispensable)
– Have to be present in the diet (absorbed)– Arg Lys Trp Leu Ile Val Met Thr Phy His
• Nonessential amino acids (dispensable)– Synthesized in body tissues– Glu Gly Asp Pro Ala Ser Cys Tyr
Proteins Peptides Amino acids
Nitrogenous Compounds in Feeds
• Nonprotein nitrogen– Nitrogen not associated with protein
• Free amino acids, nucleic acids, amines, ammonia, nitrates, nitrites, urea
• Crude protein– Total nitrogen x 6.25– Proteins on average contain 16% nitrogen
Protein Degradation in the Rumen
Feed proteins Peptides Amino acids
Undegraded feed proteinsEscaped feed proteins“Bypass proteins”
Enzymes from protozoa and bacteriaMany species of bacteria involvedBacterial enzymes are extracellularEnzymes not in cell free rumen fluidBoth exopeptidase and endopeptidase activity
Assumption in CNCPS: Enzymes (microorganisms)in excess – substrate limited
Factors Affecting Ruminal Protein DegradationChemical Nature of the proteins
• Solubility – More soluble proteins degraded faster Some soluble proteins not extensively degraded Egg ovalbumin, serum proteins• 3-dimensional structure – Affects solubility & availability• Chemical bonding
Disulfide bonds – Reduces degradationPhysical barriers
• Cell walls of plants• Cross linking of peptide chains – Reduces degradation Aldehydes, Tannins
Feed intakeRate of passage – Time proteins remain in the rumen
Feed processing• Rate of passage• Heat damage – Complexes with carbohydrates
Estimating Degradation ofDietary Proteins in the Rumen
1. In situ digestion Feed placed in Dacron bags suspended in the rumen Measure protein lost over time
2. Cannulated animals (rumen & duodenum) Measure protein flowing through duodenum Need to differentiate feed from microbes
3. In vitro incubation with rumen microbes Relative differences among proteins
4. In vitro digestion with fungal enzymes
Protein Degradation In situ
A - All degraded
B - Partly degraded Slope = degradation rate
C - Not degraded
Digestion time, hr
Lo
g,
% N
rem
ain
ing
Protein Degradation
DIP (RDP) = A + B[Kd/(Kd+Kp)]
DIP = Degraded intake proteinKd = degradation rate, %/hKp = passage rate, %/h
UIP (RUP) = B[Kp/(Kd+Kp)] + C
UIP = Undegraded intake protein
Feed Protein Fractions (CNCPS & NRC)
Soluble
Insoluble
NPN - A
Sol Proteins - B1
Insoluble - B2
Insoluble - B3
Indigestible - CFeed
Protein Fractions In FeedsLaboratory Analysis
A - Soluble in buffer (borate-phosphate) and not precipitated by tungstic acidB1 - Soluble in buffer and precipitated by tungstic acidB2 - Insoluble in buffer
= (Insol protein) - (protein insol in neutral detergent)B3 - Insoluble in buffer
= (Insol in neutral detergent) - (Insol in acid detergent)C - Insoluble in buffer and acid detergent
Kd Values for Feed Proteins
Fraction Kd, %/hA InfinityB1 120 to 400B2 3 to 16B3 0.06 to 0.55C Not degraded
Kp Values
Wet foragesKp = 3.054 + 0.614X1
Dry foragesKp = 3.362 + 0.479X1 – 0.007X2 – 0.017X3
ConcentratesKp = 2.904 + 1.375X1 – 0.020X2
X1 = DMI, % Body WtX2 = Concentrate, % of ration DMX3 = NDF of feedstuff, % DM
Feed Protein AcronymsNRC Publications
Crude protein Total N x 6.25DIP (RDP) Degraded intake proteinUIP (RUP) Undegraded intake proteinSolP, % CP Soluble proteinNPN, % CP Nonprotein nitrogenNDFIP, % CP Neutral detergent fiber insoluble
proteinADFIP, % CP Acid detergent fiber insoluble
proteinB1, B2, B3, % hr Rate constants for degradable
fractions
“Bypass proteins”
Proteins that are not extensively degraded in the rumen1. Natural
Corn proteins, blood proteins, feather meal
2. Modification of feed proteins to make them less degradable
Heat - Browning or Maillard reactionExpeller SBM, Dried DGS, Blood meal
ChemicalFormaldehydePolyphenolsTanninsAlcohol + heat
Usually some loss in availability of amino acids - lysine
Average RuminalDegradation of Several Proteins
Used in Level 1
Soybean meal (Solvent processed) 75%Soybean meal ( Expeller processed) 50%Alfalfa 80%Corn proteins 62%Corn gluten meal 42%Corn gluten feed 80%Dried distillers grains 55%Blood meal 20%Feather meal 30%Urea 100%
Degradation of NPN Compounds
Activity associated with microorganisms
• Urea CO2 + 2 NH3
High concentrations of urease activityin the rumenLow concentrations of urea in the rumen
• Biuret 2 CO2 + 3 NH3
Low activity in the rumen
• NO3 NH3
Fate of Free Amino Acids in the Rumen
1. Amino acids not absorbed from the rumen• Concentrations of free AA in the rumen very low
2. Amino acids and small peptides (up to 5 AA) transported into bacterial cells
• Na pumped out of cells – Uses ATP• Na gradient facilitates transport of AA by a carrier
3. Utilized for synthesis of microbial proteins4. Amino acids metabolized to provide energy
Amino Acid Degradation in the Rumen
NH3 CO2
Amino acids Keto acids VFA
• Enzymes from microorganismsIntracellular enzymes
• Peptides probably hydrolyzed to amino acids and then degraded
• NH3, VFA and CO2 absorbed from rumen
Amino Acid Fermentation
Valine IsobutyrateLeucine IsovalerateIsoleucine 2-methybutyrate
Alanine, glutamate, histidine, aspartate, glycine,serine, cystein and tryptophan pyruvate
Threonine, homoserine, homocyseine andmethionine Ketones
Control of Amino Acid Fermentation
When CHOH is ample for growth, incorporationof amino acids into protein is favored
• Majority of transported amino acids and peptides do not go through ammonia pool
When CHOH supply is limiting growth, aminoacids are fermented for energy
• There is an increase in amino acids going through the ammonia pool
Does Source of Carbohydrate Affect Amino Acid Fermentation?
CHOH slowly fermented or with a significant lag time• CHOH fermentation for growth might lag behind fermentation of AA
Rapidly fermented CHOH• AA fermentation and CHOH might be more closely matched
Recycling of N into the rumen might offsetdisruptions in CHOH and AA fermentations
Amino Acid Fermenters in the Rumen
High numbers Low numbers Low activity High activityButrivibrio fibrisolvens Clostridium aminophilumMeasphaera elsdenii Clostridium sticklandiiSelenomonas ruminantium Peptostreptococuss anaerobius
109 per ml 107 per ml10 to 20 NMol NH3 300 NMol NH3 per min per min per mg protein per mg proteinMonensin resistant Monensin sensitiveInvolved in CHOH Ferment CHOH slowly orfermentation not at all
Fate of Rumen Ammonia
1. Bacterial protein synthesis
2. Absorbed from reticulorumen and omasum
NH3 passes from rumen by diffusion into portal blood. (High concentration to low)
Form of ammonia dependent on pH of rumen
NH3 + H+ NH4+
Less absorption at more acid pH
3. At pH of rumen, no NH3 lost as gas
Fate of Absorbed Ammonia
1. Transported to liver by portal vein2. Converted to urea via urea cycle in liver
NH3 Urea
Urea cycle
3. Urea released into blood4. If capacity of urea cycle in liver is exceeded
Ammonia toxicityOver consumption of urea
Fate of Blood Urea
1. Excreted into urine
2. Recycled to digestive tract, g N/d
• Saliva – Related to concentration ofurea in blood
Sheep: 0.5 to 1.0Cattle: 1.0 to 7.6
• Diffusion into GITSheep: 2 to 5Cattle: 25 to 40
Adjustments to Low Protein Intake
KidneyBlood urea Urea
Urine urea
Urea is predominant form of N in urine
Reabsorption of urea by kidney increasedwhen ruminants fed low N diets
• Conserves nitrogen in the body• Greater portion recycled to digestive tract• Sheep fed the same diet tend to reabsorb more urea than cattle
Nitrogen Recycling - Cattle
05
1015202530354045
N,
g/d
87.6 110.4 147.5 178.7 203.5
N intake, g/d
GIT
Saliva
Wall
Marini et al. JAS 2003
Urea Diffusion into Rumen
Rumen wall
Bloodurea Urea
NH3
Bacterial population
1. Total N transferred isgreater when high Ndiets are fed.
2. Percentage of diet Ntransferred is greaterwhen low N diet are fed
Urea Diffusion into RumenUpdate
Rumen wall
Urea transporterBloodurea Urea
High [NH3]
inhibits
NH3
Bacterial population
Sources of Nitrogen Recycled to GIT
1. Urea flowing back into digestive tract Rumen
• Saliva• Diffusion from blood
Lower digestive tract (large intestine, colon,cecum)• Diffusion from blood• Endogenous protein secretions into GIT
Mucins Enzymes Sloughing of tissue
2. Turnover of microbial cells in rumen & reticulum
Significance of Recycled Nitrogen
Source of N for microbes when protein consumptionis limited
• Wild speciesProtein intake during winter is very lowRumen deficient of nitrogen for microbial activity
• Slowly degraded feed proteinsRecycling provides nitrogen for microbial growth
• Infrequent feeding of supplemental protein• Programs to reduce supplemental nitrogen
Difficult to make ruminants severely protein deficient
Urea Nitrogen - Cattle
020406080
100120140
N,
g/d
1.45
1.89 2.5
2.97 3.4
N, % Diet DM
Urine N Urine, Urea N
0
2
4
6
8
10
12
14
mM
1.45 2.5 3.4
N, % Diet DM
Plasm urea Saliva urea
Marini et al. JAS 2003
Microbial Protein Synthesis
End product of protein degradation is mostly NH3
Protein synthesisFixation of N in organic formSynthesis of amino acidsSynthesis of protein(s)
Bacterial ProteinSynthesis in the Rumen
NH3 Amino acids & Peptides
VFA Amino acids MicrobialFermentation proteins
CHOH VFAMicrobial protein synthesis related to:
1. Available NH3 and amino acids (DIP)2. Fermentation of CHOH - Energy
Microbial RequirementsBacteria
Nitrogen• Mixed cultures
NH3 satisfies the N requirementCross feeding can supply amino acids
• Pure culturesFiber digesters require NH3
Starch digesters require NH3 and amino acidsPeptides can be taken up by cells
Branched-chain fatty acids• Required by major rumen cellulolytic bacteria
Energy from fermentation• Need energy for synthesis of macromolecules
Amino Acid SynthesisAmmonia Fixation
1. Glutamine synthetase/glutamate synthase• Glutamine synthetase Glu + NH3 + ATP Gln
• Glutmate synthase -ketoglutarate + glutamine + NADPH2
2 Glu
High affinity for NH3 - Concentrates NH3 incells – Uses ATPBecause of N recycling this reaction may notbe that important
Amino Acid SynthesisAmmonia Fixation
2. Glutamic dehydrogenase• -ketoglutarate + NH3 + NADH Glu
Low affinity for NH3 – High concentration ofenzyme in rumen bacteria – Does not use ATP
Probably predominant pathway
3. Other AA can be synthesized by transamination reactions with glutamic acid
Estimates of NH3 requirements range from 5 (culture)to 20 mg/100 ml (in situ digestion)
Role of Protozoa
Do not use NH3 directly
Engulf feed particles and bacteria• Digest proteins• Release amino acids and peptides into rumen• Use amino acids for protein synthesis• Protozoa engulf bacteria• Protozoa lyse easily – May contribute little
microbial protein to the animal
Efficiency of Microbial Growth
Grams microbial N/100 g organic matter digestedRanges from 1.1 to 5.0
1. Kind of diet Forages > Grain2. Level of feeding High > Low3. Rate of passage Fast > Slow4. Turnover of microbial cells
Younger cells turnover less than aging cells5. Maintenance requirement of cells
Microbes use energy to maintain cellular integrity6. Energy spilling
Dissipation of energy different from maintenanceMost apparent when energy is in excess
Efficiency of Microbial Growth
TDN, % feed DM
G B
CP
/100
g T
DN
813
Slow Low rumenpassage pH
Bacteria
Low quality use energy to forages slow pump protons passage
Microbial Growth in The Rumen
Nutrients available to microbes1. DIP - NH3, peptides, amino acids
• CNCPS adjusts for inadequate available N2. Energy from the fermentation
• Growth rate related to Kd of CHOH• Quantity of cells related to CHOH digested
CNCPS assumes microbes digestingnon-fiber and fiber CHOH both havea maximum yield of 50g cells/100gCHOH fermented
3. Other - branched-chain acids, minerals
Microbial GrowthComputer Models
1996 Beef NRC
BCP (g/d) = 0.13 (TDN, g/d)Can vary the 0.13Lower when poor quality forages fed
1989 Dairy NRCCattle consuming more than 40% of intake as forage:
BCP g/d) = 6.25 (-31.86 + 26.12 TDN, kg/d)
Microbial Growth Computer Models
2001 Dairy NRC and Level 1 CNCPS
BCP (g/d) = 0.13 (TDN, g/d)Correct TDN for fat added to the ration
Fat does not provide energy to the bacteria
Requirement for RDP (DIP) is 1.18*BCP Microbes capture 85% of available N
If RDP < 1.18*BCP:BCP (g/d) = 0.85* RDP
Composition of RumenMicroorganisms
N fraction, % total Bacteria Protozoa
Amino acids 82.5 86.5
RNA 10.0 8.7
DNA 5.0 2.5
True digestibility, % 80.0
Nutritional Value of Microbial Proteins
1996 NRC for BeefMicrobial protein 80% digestible in the intestine
UIP 80% digestible in the intestine
2001 NRC for Dairy and Level 1 CNCPSMicrobial protein 80% digestible in the intestine
Digestibility of RUP (UIP) is variable in Dairy NRCUIP 80% digestible in Level 1 CNCPS
Amino Acid Composition% Crude Protein or G/100g CP
Tissue Milk ----------Bact ---------- Corn Soy
Cell wall Non wall Mean
Methionine 1.97 2.71 2.40 2.68 2.60 2.28 1.46
Lysine 6.37 7.62 5.60 8.20 7.90 3.03 6.32
Histidine 2.47 2.74 1.74 2.69 2.00 3.16 2.72
Phenylalanine 3.53 4.75 4.20 5.16 5.10 5.32 5.65
Tryptophan 0.49 1.51 NA 1.63 - 0.89 1.46
Threonine 3.90 3.72 3.30 5.59 5.80 3.67 4.18
Leucine 6.70 9.18 5.90 7.51 8.10 12.66 7.95
Isoleucine 2.84 5.79 4.00 5.88 5.70 3.67 5.44
Valine 4.03 5.89 4.70 6.16 6.20 5.32 5.65
Arginine 3.30 3.40 3.82 6.96 5.10 5.06 7.53
Amino Acids inUndegraded Feed Proteins
His Isl Lys MetFish meal 3.4 4.2 6.6 3.1Fish meal residue 2.9 4.9 6.0 2.9
Meat & bone meal 1.5 2.1 4.2 1.0Meat & bone meal residue 1.4 2.3 4.3 1.0
Sources of Amino Acids for Host Animal
1. Microbial proteinsQuantity determined by:
a) Fermentability of the feedb) Quantity of feed consumedc) Nitrogen available to microorganisms
2. Undegraded feed proteins (UIP)Quantity will vary in relation to:
a) Degradability of feed proteinsb) Quantity of feed proteins consumed
History of Protein Systems for Ruminants
• ISU Metabolizable protein system• Wisconsin system – When urea could be used• Several European systems – Mostly MP systems• 1985 NRC system – Summarized systems &
Proposed a MP system
Used in 1989 Dairy NRC• Cornell CNCPS• 1996 Beef NRC system – Mostly CNCPS system
Used in ISU Brands system• 2001 Dairy NRC system
NH3 Blood urea Urine Amino acid pools
Energy NH3 Metabolizable Microbial protein
protein Protein
Proteinfrom diet
Rumen Intestine Feces
A
B
C
Metabolizable Protein Model
Tissue proteins
Protein Metabolism of RuminantsConcept of Metabolizable Protein
Metabolizable protein (MP) = Absorbed amino acids or = Digestible fraction of microbial proteins + digestible fraction of undegraded feed proteins
Digestible protein (amino acids) available for metabolism
Concept is similar to Metabolizable energy
Feed Rumen Intestine
DigestionMicrobes
Undegraded feedMetabolizable protein
Protein Metabolism in the RumenLess Extensively Degraded Protein
Feed Rumen Intestine
DigestionMicrobes
Undegraded feedMetabolizable protein
Protein Metabolism in the RumenExtensively Degraded Protein
NH3
Metabolizable ProteinSupply to Host Animal
Metabolizable protein (MP):Microorganisms – Digestible proteinsUndegraded feed proteins – Digestible proteins
Microorganismsg/d = 0.13 (TDN intake, g/d) (0.8) (0.8) Microbes 80% true protein that is 80% digested
Feedg/d = (Feed protein) (Portion undegraded) (0.8) Feed proteins 80% digested
Absorption of Amino Acids
Amino acids and small peptides absorbedby active transport (specific for groups of AA)
From intestines Portal blood
Transport of amino acids into cells issimilar process
From blood Cells
Active transport, requires energy
Utilization of Absorbed Amino Acids
Via portal vein to liver• Used for synthesis of proteins in liver• Metabolized (deaminated) - Used for energy – Carbon for glucose• Escape the liver
Carried by blood to body tissues• Used for synthesis of tissue proteins, milk, fetal growth, wool• Metabolized - Used for energy
Requirements for Absorbed Amino AcidsMetabolizable Protein (MP)
Protein (amino acid) requirements1. Maintenance2. Growth3. Lactation4. Pregnancy5. Wool
Protein MetabolismConcept of Net Protein
Net protein = protein gained in tissues, milk, or fetal growth = NP
Metabolizable protein is used with lessthan 100% efficiency
Net protein = (MP - Metabolic loss)
As a quantity, net protein is less thanmetabolizable protein
Protein MetabolismMetabolic Loss
Protein synthesis and metabolism ofamino acids draw from the same pool
ProteinsAmino acids
Metabolism
• Metabolic loss results from continuous catabolism from amino acid pools• Continuous turnover of tissue proteins adds to amino acid pools in tissues
Amino Acid (MP) RequirementsMaintenance (three fractions)Protein required to support zero gain or production
1. Metabolism Metabolized Urine
Milk Amino acids FecesWool (Synthesis) GITScurf (Degradation)Pregnancy Tissue proteins= Endogenous urinary N
2. Proteins lost from body surface (hair, skin, secretions) = Scurf proteins3. Proteins lost from undigested digestive secretions and fecal bacteria = Metabolic fecal N
Maintenance Requirements forMetabolizable Protein
1. Maintenance (1996 Beef NRC)
3.8 g MP/kg BW.75
2. Maintenance (2001 Dairy NRC & CNCPS)Endogenous urinary N
UPN = (2.75 x SBW0.50)/0.67Scurf N
SPN = (0.2 x SBW0.60)/0.67Metabolic fecal N
Dairy NRC: (DMI kg x 30) – 0.50 x ((bact MP/0.80) – (bact MP)CNCPS: 0.09 x (100 – digestible DM)
Maintenance Requirements forMetabolizable Protein
BW, lbs B NRC CNCPS NRC(85) ISU
D NRC MP
400 188 138 135 128
600 255 180 174 182
800 316 215 211 234
1000 374 250 244 284
1200 429 272 276 334
Relationship of Metabolizable ProteinIntake and Gain
Gain, kg/d
0 1
MP
, g/d
200
300
400
500
600
700
MP = 252.57 + 286.62 X Gain3.8 g MP/kg BW.75
Net Protein Required for Production
Amino Acids Proteins
Milkkg/d = (Milk yield, kg/d) (% protein in milk)
Growthg/d = SWG (268 - (29.4 (RE/SWG)))
SWG = Shrunk weight gain, kg/dRE = Retained energy, Mcal/d
RE obtained from net energy equations.
Efficiency of Utilization ofMetabolizable Protein for Deposition of Net Protein
1. Growth
Beef NRCIf EQEBW < 300 kg
0.834 – (0.00114 x EQEBW)Otherwise 0.492
Dairy NRCIf EQEBW < 478 kg
0.834 – (0.00114 x EQEBW)Otherwise 0.289
Efficiency of Utilization ofMetabolizable Protein for Deposition of Net Protein
2. LactationProtein in milk/0.65 (Beef NRC)Protein in milk/0.67 (Dairy NRC)
3.PregnancySee equations in publications
Growth of Cattle – Change in Body Composition
0
10
20
30
40
50
60
70
Per
cen
t
400 800 1200
Empty Body Wt, lbs
Water
Protein
Fat
Ash
ISU experiments
Protein Requirements of Growing CattleChanges with Increase in Weight
0100200300400500600700800900
Met
abo
liza
ble
P
rote
in R
equ
ired
, g
/d
600 700 800 900 1000 1100 1200 1300
Weight, lbs
Gain Maintenance Total
Example CalculationLevel 1
300 kg steerGaining 1.37 kg SBW/d
10.7% protein in gainConsuming 6.8 kg feed DM
11.5% crude protein, 30% UIP80% TDN
Is this steer being fed adequate protein?
300 kg Steer
MP requirement:Maintenance (Beef NRC)
3.8 (300.75) = 273.9 g/d
Gain(1.37 (.107)/.5) (1000) = 293.2 g/d
Total requirement273.9 + 293.2 = 567.1 g/d
300 kg Steer
MP supplied:UIP
(6.8 (.115) (.3) (.8)) 1000 = 187.7 g/d
Microbial(6.8 (.80) (.13) (.8) (.8)) 1000 = 452.6 g/d
Total MP supplied187.7 + 452.6 = 640.3 g/d
Requirement = 567.1 Supply = 640.3
Conclusion: Steer has adequate dietary protein
300 kg Steer
Was there enough protein degraded in the rumen to furnish the nitrogen needs of the microorganisms to produce BCP?
(6.8 (0.80) (0.13)) 1000 = 707.2 g/d BCP
(6.8 (.115) (.7))1000 = 547.4 g/d DIP
So this diet is short of DIP by 159.8 g/d
Would appear as negative ruminal N balance in CNCPS model
Consequences of Shortage of DIP
Synthesis of bacterial protein is limited547.4 g rather than 707.2
547.4 (.8) (.8) = 350.3 g MP from microbes350.3 + 187.7 = 538.0 g MP supplied to steer
567.1 (requirement) - 538.0 (supply) = 29.1 g/d shortage
Steer would not gain 1.37 kg/d according to model
How Can Rumen AvailableNitrogen be Increased?
Feed more degradable proteinUsually expensive to do so unless more MP is also needed
Feed nonprotein nitrogen such as ureaAll is degraded to NH3.
Usually cost is least
Does more DIP have to be added?Models indicate yes
Supplementing Ruminal Available Nitrogen
Urea ($300/ton)159.8/2.8 = 57.1 g/d of urea could be added
Urea is 280% crude proteinCost: 57.1 x 0.00033 = $0.0189/d
Soybean meal ($200/ton)(159.8/0.75)/0.5 = 426.1/0.9 = 473.5 g/dCost: 473.5 x 0.00022 = $0.1043/d
Dry DGS ($80/ton)(159.8/0.5)/0.3 = 1065.3 g/dCost: 1065.3 x 0.00009 = $0.0937/d
Should: Correct urea for additional corn fed Correct DGS for corn replaced
Cost corn ($2.00/bu) = $0.04/lb DM
Supplementation of Diets with Urea
If inadequate DIP is available for synthesisof BCP, need to add degradable N
Can add urea
Urea Fermentation Potential (g urea/kg diet DM)
UFP = (BCP, g/kg - DIP, g/kg)/2.8kg = kg diet DM2.8 = Urea is 280% crude protein
+ UFP: Inadequate DIP, urea will benefit- UFP: There is surplus DIP, urea of no benefit
Feed Values Beef NRC
% DIP % TDN % CP Soybean meal 65 87 49 Dry corn 45 90 9.8 Corn silage 75 75 8.0 Alfalfa hay 82 60 17 Fescue hay 67 56 9.1 Corn stalks 68 55 6.3
Protein Values for Feeds
DIP, g/kg
BCP, g/kg
UFP, g/kg
Soybean meal 318.5 113.1 -73.4
Corn 44.1 117.0 26.0
Corn silage 60.0 97.5 13.4
Alfalfa hay 139.4 78.0 -21.9
Fescue hay 61.0 72.8 4.2
Corn stalks 42.8 71.5 10.2
What is The Requirement for DIP? Finishing Cattle
Cooper et al. JAS 2002Fed different concentrations of urea to finishing steersDiets: Dry rolled, high moisture and steam flaked cornMeasured feed intake and gain
Estimated requirement for DIP (DIP as % of diet DM)Dry rolled – 6.3High moisture – 10.0Steam flaked – 9.5
High moisture and steam flaked corns more digestiblein the rumen – Increased microbial protein production
Limitations:Protein requirements change during the experiment
Programmed Feeding of Supplemental ProteinFeedlot Steers - ISU
Program Crude protein, % DM
(MP – DIP, Percent of requirement)
Source within period 1 to 42 d 43 to 84 d 85 to 135 d
Program I
SBM-SBM-SBM
12.4(104 -101)
12.4(127 – 101)
12.4(151 – 101)
Program II
Urea-Urea-Urea
11.7(96 – 101)
11.7(117 – 101)
11.7(138 – 101)
Program III
SBM-Urea-Urea
12.4(104 – 101)
11.7(119 – 101)
11.7(140 – 101)
Program IV
SBM-Urea-Lo Urea
12.4(104 – 101)
11.7(119 – 101)
10.0(123 – 80)
Programmed Feeding of Supplemental Protein740 lb Feedlot Steers
I II III IV
0 – 42 d, ADG 3.95 3.56 4.13 4.03
Feed/d 15.7 15.6 15.7 15.6
43 – 84 d, ADG 4.32 4.38 4.16 4.44
Feed/d 21.6 21.3 21.1 21.3
85 – 135 d, ADG 3.21 3.14 2.99 3.17
Feed/d 22.5 22.2 22.3 22.8
0 – 135 d, ADG 3.79 3.66 3.71 3.85
Feed/d 20.1 20.0 19.9 20.1
What is The Requirement for DIP?Conclusions
5
6
7
8
9
10
-1 1 3 5 7 9
Hours
Ure
a, m
g/1
00 m
l
11.7 10 9
All of calculated DIP does not have to be satisfiedwhen MP is being fed in excess
• Enough nitrogen is recycling• Reduces quantity of nitrogen fed
0
10
20
30
40
50
60
70
80
Ap
par
ent
dig
esti
bil
ity,
%
DM OM CP NDF
11.7 10 9
If Diet Needs More Metabolizable Protein
First considerationCan microbial protein be increased?
If short of ruminal available NAdd ureaProvide ammonia to microorganisms
If surplus of rumen available NAdd fermentable feed (TDN)Provide energy to microorganisms
Second considerationSupplement diet with less degradable protein
Application of Metabolizable Protein System to Feedlot Cattle
Supplement protein in relation to requirementOptimize performance
• High performing cattlePhase feed supplemental protein
• Change supplement in relation to rate and composition of gain• Use computer programs• Supplement to minimize environmental impact
Protein Requirements of Growing CattleRelation to Rate of Gain
600
620
640
660
680
700
720
740
Met
abo
liza
ble
pro
tein
, g
/d
1.75 1.87 1.97 2.07
Rate of gain, kg/d
Increased Protein RequirementsRuminants
Situation Consequences1. Young animals Leaner gain Fast rate of gain More total protein Leaner gain in tissues2. Compensatory gain Greater muscle growth3. High levels of lactation More milk protein4. Hormone implants and bGH More protein synthesis5. Low feed intakes Less MP from diet High energy diets and microbes
Need to feed higher concentrations of protein or less degradable protein
Effects of Feeding Soybean MealFeedlot Steers
Supplement
Urea SBM
% CP in diet 11.5 14.0
ADG, lb/d 3.71 4.10
Feed DM, lb/d 21.5 22.9
Feed/gain 5.86 5.66
Yearling steers, Revalor implants
At high rates of gain, cattle respond to bypass protein.
Effects of Feeding More Urea
% Crude protein
11.5 14.0
ADG, lb/d 3.63 3.57
Feed DM, lb/d 21.2 21.6
Feed/gain 6.02 6.04
Yearling steers, Revalor implant
If DIP requirement is met, no response to feedingmore urea.
Effects of Level of Soybean MealFed to Feedlot Steers
% SBM
Urea 5 10
% CP in diet 14 14 14
ADG, lb 3.58 3.83 3.94
Feed DM, lb/d 22.4 22.1 22.4
Feed/gain 6.28 5.80 5.70
Yearling steers, Revalor implants
Greatest response to first addition of bypass protein.
Changing SBM Supplement to Urea Phase Feeding
Diet
Urea SBM SBM-U
% CP in diet 11.5 14 14-11.5
ADG, lb/d 3.89 4.25 4.14
Feed DM, lb/d 22.5 22.8 22.2
Feed/gain 5.86 5.40 5.40
Yearling steers, Revalor implant
Cattle require less protein as they approach mature finished weightsIndustry standard is 13.5 to 14% crude protein for finishing cattle
Nitrogen Balance - Feedlot Steers680 to 1377 lbs
Implanted and fed 14% crude protein
Start End Gain Lbs body N 18.7 31.6 12.9 N fed, lbs 96.5
N excreted, lbs 83.6
N excreted, % 86.6
N excreted from 10,000 steers = 418 tons
Cattle retain 10 to 15% of dietary N during finishing.
Phase Feeding of Protein830 lb Steers
3
3.5
4
4.5
5
5.5
6
Lb
s
Urea SBM SBM-U
Source of protein
ADG F/G
3
3.5
4
4.5
5
5.5
6
Lb
s
Urea SBM SBM-U
Source of protein
ADG F/G
0 to 61 days 0 to 130 days
11.0 14.0 14.0 11.0 14.0 11.0
Diets to Feed in a Phase ProgramTheoretical Feeding Program
Diet I II III Corn 71.5 78.4 81.6 Corn silage 10.0 10.0 10.0 Alfalfa hay 5.0 5.0 5.0 Expeller SBM 11.0 3.5 Urea 0.33 0.83 1.09 Supplement 2.17 2.27 2.31 Crude protein, % 13.8 12.3 11.6
Crude protein: Corn 9.0%, Hay 16.0%
Rumen Degradable and Metabolizable Protein Theoretical Phase-Fed Diets
5060708090
100110120130140150
Per
cen
t o
f re
qu
irem
ent
600 800 900 1000 1200
Body wt, lbs
Metabolizable protein Rumen available protein
Diet: I II III III III
Nitrogen excreted from 10,000 head feedyard: 312.9 tons
Develop Diets with Low Protein Ingredients Reduce Nitrogen Excretion
Diet I II III IV Corn 68.2 74.2 78.4 81.2 Corn silage 10.0 10.0 10.0 10.0 Alfalfa hay 5.0 5.0 5.0 5.0 Expeller SBM 14.0 7.6 3.0 Urea 0.52 0.99 1.32 1.54 Supplement 2.28 2.21 2.28 2.26 Crude protein, % 13.5 12.2 11.2 10.5
Crude protein: Corn 6.0%, Hay 10.0%
Rumen Degradable and Metabolizable Protein in Phase-Fed Diets
5060708090
100110120130140150
Per
cen
t o
f re
qu
irem
ent
600 800 900 1000 1200
Body wt, lbs
Metabolizable protein Rumen available protein
Diet: I II III IV IV
Nitrogen excreted from 10,000 head feedyard: 283 tons
Response to Feeding UreaKSU Study
0
20
40
60
80
100
120
Per
cen
t o
f re
qu
irem
ent
0 0.5 1
% Urea
Metabolizable protein Rumen available protein
Response to Feeding UreaFinishing Steers
% Urea
0 0.50 1.00
Feed DM, lb/d 24.4 23.1 24.0
ADG, lbs 3.34 3.52 3.63
Gain/feed 0.137 0.153 0.152
KSU, 1997 - 730 lb steers fed 154 days.Diet: Dry rolled corn and 10% prairie hay.
Response to Implants and Protein700 lb Steers
2
2.5
3
3.5
4
4.5
5
5.5
6
Lb
s
9.5 11
12
.5
9.5 11
12
.5 14
Dietary crude protein, %
ADG F/G
--No Implant-- --------Implant-------
0
1
2
3
4
5
6
7
8
Lb
s
11 11 14
Dietary crude protein, %
ADG F/G
No Implant -----Implant-----
0 to 85 days 86 to 186 days
Effect of Implants on Nitrogen Retention Feedlot Steers
101112131415161718
1920
N
Ret
ain
ed
P
erce
nt
of
N c
on
sum
ed
C - 11% C - 12.5% I - 9.5% I - 14%
Protein Requirements of Lactating Cows
0
500
1000
1500
2000
2500
3000
Me
tab
oli
zab
le p
rote
in,
g/d
20 30 40
Milk, kg/d
MaintenanceLactationTotal
Protein Requirements of Dairy Cows
Milk yieldComposition of milk
Body weightMaintenanceBody weight change
Pregnancy
Meeting Dairy Cow’s Protein Requirement
• Feed intakeNature of feed ingredients
Fermentable energyMicrobial protein synthesis in the rumen
Proportion of feed protein(s) degraded• Digestibility of proteins in the intestine• Amino acids available for absorption
Amino acid balance
Recommendations for Feeding High RUP Byproducts to Dairy Cows
CP RUP Recom intake
ByProd CP intake
ByProd CP intake
% % lb/d lb/d % total
Blood meal 87 82 .75-1.0 .87 9.7
Feather meal 92 71 .5-1.0 .92 10.2
Meat & bone 54 70 2.0-2.5 1.35 15.0
Fishmeal 67 60 1.0-2.0 1.34 14.9
Corn gluten meal 67 55 2.0-3.0 2.01 22.3
Corn distill. grain 30 47 4.0-6.0 1.80 20.0
Soybean meal 52 33
Extruded SBM 49 61 Feed as needed
Extruded soybeans 43 54 Oil intake might limit
Roasted soybeans 43 62
Digestibility of RUPDairy NRC
CP, % RUP, % dig Grass/legume hay 19.1 70 Corn silage 8.8 70 Soy hulls 13.9 70 Corn, dry cracked 9.4 90 Soybean meal 53.8 93 Dry distillers grains 29.7 80 Corn gluten meal 65.0 92 Fish meal 68.5 88 Hydrolyzed feathers 92.0 65
Why Limit High RUP Proteins?Lactating Cows
• Animal byproducts tend to reduce feed intakePalatabilityFat content (Fish meal decreases milk fat)
Decreased feed intake reducesmicrobial protein synthesis
• Plant byproducts may have poor amino acid balance
Corn proteins deficient in lysine and tryptophanDigestibility of RUP (UIP)
• Might create a deficiency of RDP (DIP)• Quality of RUP proteins can be variable
Why a Variable Response to RUP?Lactating Cows
• Protein requirements may have been metProtein might not be first limitingCows mobilizing body proteins
• First limiting amino acid might not be increasedAmino acid ratios of metabolizable proteinDigestibility of RUP
• Use of RUP might cause a shortage of RDP• Overestimation of degradation of other supplemental proteins
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