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