Protein Metabolism Ruminants Subjects to be covered

1
Protein Metabolism RuminantsSubjects to be
covered

• Digestion and metabolism in the
• rumen
• Protein requirements of ruminants
• Models
• Define requirements
• Describe feeds
• Optimize production
• Environmental issues
• Prevent overfeeding nitrogen

2
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-CO R2 N-C-COOH H
R3
3
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

4
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

5
Protein Degradation in the Rumen
Feed proteins Peptides Amino acids Undegraded
feed proteins Escaped feed proteins Bypass
proteins Enzymes from protozoa and
bacteria Many species of bacteria
involved Bacterial enzymes are extracellular Enzym
es not in cell free rumen fluid Both exopeptidase
and endopeptidase activity Assumption in CNCPS
Enzymes (microorganisms) in excess substrate
limited
6
Factors Affecting Ruminal Protein Degradation

• Chemical 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 degradation
• Physical barriers
• Cell walls of plants
• Cross linking of peptide chains Reduces
  degradation
• Aldehydes, Tannins
• Feed intake
• Rate of passage Time proteins remain in the
  rumen
• Feed processing
• Rate of passage
• Heat damage Complexes with carbohydrates

7
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
8
Protein Degradation In situ
Log, N remaining
A - All degraded
B - Partly degraded Slope degradation rate
C - Not degraded
Digestion time, hr
9
Protein Degradation
DIP (RDP) A BKd/(KdKp) DIP
Degraded intake protein Kd degradation rate,
/h Kp passage rate, /h UIP (RUP)
BKp/(KdKp) C UIP Undegraded intake protein
10
Feed Protein Fractions (CNCPS NRC)
NPN - A Sol Proteins -
B1 Insoluble - B2 Insoluble -
B3 Indigestible - C
Soluble
Insoluble
Feed
11
Protein Fractions In FeedsLaboratory Analysis
A - Soluble in buffer (borate-phosphate) and not
precipitated by tungstic acid B1 - Soluble
in buffer and precipitated by tungstic acid B2 -
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
12
Kd Values for Feed Proteins
Fraction Kd, /h A Infinity B1 120 to
400 B2 3 to 16 B3 0.06 to 0.55 C Not
degraded
13
Kp Values
Wet forages Kp 3.054 0.614X1 Dry forages Kp
3.362 0.479X1 0.007X2 0.017X3 Concentrate
s Kp 2.904 1.375X1 0.020X2 X1 DMI,
Body Wt X2 Concentrate, of ration DM X3 NDF
of feedstuff, DM
14
Feed Protein AcronymsNRC Publications
Crude protein Total N x 6.25 DIP (RDP) Degraded
intake protein UIP (RUP) Undegraded intake
protein SolP, CP Soluble protein NPN,
CP Nonprotein nitrogen NDFIP, CP Neutral
detergent fiber insoluble protein ADFIP,
CP Acid detergent fiber insoluble protein B1,
B2, B3, hr Rate constants for
degradable fractions
15
Bypass proteins
Proteins that are not extensively degraded in
the rumen 1. Natural Corn proteins, blood
proteins, feather meal 2. Modification of feed
proteins to make them less degradable Heat -
Browning or Maillard reaction Expeller SBM, Dried
DGS, Blood meal Chemical Formaldehyde Polyphenols
Tannins Alcohol heat Usually some loss in
availability of amino acids - lysine
16
Average RuminalDegradation of Several
ProteinsUsed 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
17
Degradation of NPN Compounds

• Activity associated with microorganisms
• Urea CO2 2 NH3
• High concentrations of urease activity
• in the rumen
• Low concentrations of urea in the rumen
• Biuret 2 CO2 3 NH3
• Low activity in the rumen
• NO3 NH3

18
Fate of Free Amino Acids in the Rumen

• Amino acids not absorbed from the rumen
• Concentrations of free AA in the rumen very low
• 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 proteins
• 4. Amino acids metabolized to provide energy

19
Amino Acid Degradation in the Rumen

• NH3 CO2
• Amino acids Keto acids VFA
• Enzymes from microorganisms
• Intracellular enzymes
• Peptides probably hydrolyzed to amino acids
• and then degraded
• NH3, VFA and CO2 absorbed from rumen

20
Amino Acid Fermentation
Valine Isobutyrate Leucine Isovalerate Isol
eucine 2-methybutyrate Alanine, glutamate,
histidine, aspartate, glycine, serine, cystein
and tryptophan pyruvate Threonine, homoserine,
homocyseine and methionine Ketones
21
Control of Amino Acid Fermentation

• When CHOH is ample for growth, incorporation
• of 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, amino
• acids are fermented for energy
• There is an increase in amino acids going
• through the ammonia pool

22
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 offset
• disruptions in CHOH and AA fermentations

23
Amino Acid Fermenters in the Rumen
High numbers Low numbers Low
activity High activity Butrivibrio
fibrisolvens Clostridium aminophilum Measphaer
a elsdenii Clostridium sticklandii Selenomonas
ruminantium Peptostreptococuss
anaerobius 109 per ml 107 per ml 10 to 20
NMol NH3 300 NMol NH3 per min per min per
mg protein per mg protein Monensin
resistant Monensin sensitive Involved in
CHOH Ferment CHOH slowly
or fermentation not at all
24
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
25
Fate of Absorbed Ammonia
1. Transported to liver by portal vein 2.
Converted to urea via urea cycle in
liver NH3 Urea Urea cycle 3.
Urea released into blood 4. If capacity of urea
cycle in liver is exceeded Ammonia toxicity Over
consumption of urea
26
Fate of Blood Urea

• 1. Excreted into urine
• 2. Recycled to digestive tract, g N/d
• Saliva Related to concentration of
• urea in blood
• Sheep 0.5 to 1.0
• Cattle 1.0 to 7.6
• Diffusion into GIT
• Sheep 2 to 5
• Cattle 25 to 40

27
Adjustments to Low Protein Intake

• Kidney
• Blood urea Urea
• Urine urea
• Urea is predominant form of N in urine
• Reabsorption of urea by kidney increased
• when 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

28
Nitrogen Recycling - Cattle
Marini et al. JAS 2003
29
Urea Diffusion into Rumen
Rumen wall Blood urea Urea
NH3 Bacterial population

• Total N transferred is
• greater when high N
• diets are fed.
• 2. Percentage of diet N
• transferred is greater
• when low N diet are fed

30
Urea Diffusion into RumenUpdate
Rumen wall Urea transporter Blood urea
Urea High NH3 inhibits NH3
Bacterial population
31
Sources of Nitrogen Recycled to GIT

• 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
• Turnover of microbial cells in rumen reticulum

32
Significance of Recycled Nitrogen

• Source of N for microbes when protein consumption
• is limited
• Wild species
• Protein intake during winter is very low
• Rumen deficient of nitrogen for microbial
  activity
• Slowly degraded feed proteins
• Recycling provides nitrogen for microbial growth
• Infrequent feeding of supplemental protein
• Programs to reduce supplemental nitrogen
• Difficult to make ruminants severely protein
  deficient

33
Urea Nitrogen - Cattle
Marini et al. JAS 2003
34
Microbial Protein Synthesis
End product of protein degradation is mostly
NH3 Protein synthesis Fixation of N in organic
form Synthesis of amino acids Synthesis of
protein(s)
35
Bacterial ProteinSynthesis in the Rumen
NH3 Amino acids Peptides VFA Amino
acids Microbial Fermentation proteins CHOH
VFA
Microbial protein synthesis related to 1.
Available NH3 and amino acids (DIP) 2.
Fermentation of CHOH - Energy
36
Microbial RequirementsBacteria

• Nitrogen
• Mixed cultures
• NH3 satisfies the N requirement
• Cross feeding can supply amino acids
• Pure cultures
• Fiber digesters require NH3
• Starch digesters require NH3 and amino acids
• Peptides 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

37
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 in
• cells Uses ATP
• Because of N recycling this reaction may not
• be that important

38
Amino Acid SynthesisAmmonia Fixation

• 2. Glutamic dehydrogenase
• ?-ketoglutarate NH3 NADH Glu
• Low affinity for NH3 High concentration of
• enzyme 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)

39
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

40
Efficiency of Microbial Growth

• Grams microbial N/100 g organic matter digested
• Ranges from 1.1 to 5.0
• 1. Kind of diet Forages gt Grain
• 2. Level of feeding High gt Low
• 3. Rate of passage Fast gt Slow
• 4. Turnover of microbial cells
• Younger cells turnover less than aging cells
• Maintenance requirement of cells
• Microbes use energy to maintain cellular
  integrity
• Energy spilling
• Dissipation of energy different from maintenance
• Most apparent when energy is in excess

41
Efficiency of Microbial Growth
Slow Low rumen passage pH
Bacteria Low quality use energy to
forages slow pump protons passage
G BCP/100 g TDN 8 13
TDN, feed DM
42
Microbial Growth in The Rumen

• Nutrients available to microbes
• DIP - NH3, peptides, amino acids
• CNCPS adjusts for inadequate available N
• 2. Energy from the fermentation
• Growth rate related to Kd of CHOH
• Quantity of cells related to CHOH digested
• CNCPS assumes microbes digesting
• non-fiber and fiber CHOH both have
• a maximum yield of 50g cells/100g
• CHOH fermented
• 3. Other - branched-chain acids, minerals

43
Microbial GrowthComputer Models
1996 Beef NRC BCP (g/d) 0.13 (TDN, g/d) Can
vary the 0.13 Lower when poor quality forages
fed 1989 Dairy NRC Cattle consuming more than
40 of intake as forage BCP g/d) 6.25
(-31.86 26.12 TDN, kg/d)
44
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 1.18BCP
Microbes capture 85 of available N If RDP lt
1.18BCP BCP (g/d) 0.85 RDP
45
Composition of RumenMicroorganisms
46
Nutritional Value of Microbial Proteins
1996 NRC for Beef Microbial protein 80
digestible in the intestine UIP 80 digestible
in the intestine 2001 NRC for Dairy and Level 1
CNCPS Microbial protein 80 digestible in the
intestine Digestibility of RUP (UIP) is variable
in Dairy NRC UIP 80 digestible in Level 1 CNCPS
47
Amino Acid Composition Crude Protein or G/100g
CP
48
Amino Acids inUndegraded Feed Proteins
His Isl Lys Met Fish meal 3.4 4.2 6.6 3.1
Fish meal residue 2.9 4.9 6.0 2.9 Meat bone
meal 1.5 2.1 4.2 1.0 Meat bone meal
residue 1.4 2.3 4.3 1.0
49
Sources of Amino Acids for Host Animal

• 1. Microbial proteins
• Quantity determined by
• Fermentability of the feed
• Quantity of feed consumed
• c) Nitrogen available to microorganisms
• 2. Undegraded feed proteins (UIP)
• Quantity will vary in relation to
• a) Degradability of feed proteins
• b) Quantity of feed proteins consumed

50
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

51
Metabolizable Protein Model
Tissue proteins
NH3 Blood urea Urine Amino
acid pools Energy
NH3 Metabolizable Microbial
protein protein Protein Protein from
diet Rumen Intestine Feces
A
B
C
52
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
53
Protein Metabolism in the Rumen Less Extensively
Degraded Protein
Feed Rumen Intestine
Microbes
Digestion
Metabolizable protein
Undegraded feed
54
Protein Metabolism in the Rumen Extensively
Degraded Protein
Feed Rumen Intestine
Microbes
Digestion
NH3
Metabolizable protein
Undegraded feed
55
Metabolizable ProteinSupply to Host Animal
Metabolizable protein (MP) Microorganisms
Digestible proteins Undegraded feed proteins
Digestible proteins Microorganisms g/d 0.13
(TDN intake, g/d) (0.8) (0.8) Microbes 80 true
protein that is 80 digested Feed g/d (Feed
protein) (Portion undegraded) (0.8) Feed
proteins 80 digested
56
Absorption of Amino Acids
Amino acids and small peptides absorbed by
active transport (specific for groups of
AA) From intestines Portal blood Transport
of amino acids into cells is similar
process From blood Cells Active
transport, requires energy
57
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

58
Requirements for Absorbed Amino
AcidsMetabolizable Protein (MP)

• Protein (amino acid) requirements
• Maintenance
• Growth
• Lactation
• Pregnancy
• Wool

59
Protein MetabolismConcept of Net Protein
Net protein protein gained in tissues,
milk, or fetal growth NP Metabolizable protein
is used with less than 100 efficiency Net
protein (MP - Metabolic loss) As a quantity,
net protein is less than metabolizable protein
60
Protein MetabolismMetabolic Loss

• Protein synthesis and metabolism of
• amino acids draw from the same pool
• Proteins
• Amino
• acids
• Metabolism
• Metabolic loss results from continuous
• catabolism from amino acid pools
• Continuous turnover of tissue proteins adds
• to amino acid pools in tissues

61
Amino Acid (MP) Requirements
Maintenance (three fractions) Protein required to
support zero gain or production 1. Metabolism
Metabolized Urine Milk Amino
acids Feces Wool (Synthesis)
GIT Scurf
(Degradation) Pregnancy Tissue proteins
Endogenous urinary N 2. Proteins lost from body
surface (hair, skin, secretions) Scurf
proteins 3. Proteins lost from undigested
digestive secretions and fecal bacteria
Metabolic fecal N
62
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)/0.67 Scurf N SPN (0.2 x
SBW0.60)/0.67 Metabolic fecal N Dairy NRC (DMI
kg x 30) 0.50 x ((bact MP/0.80) (bact
MP) CNCPS 0.09 x (100 digestible DM)
63
Maintenance Requirements forMetabolizable Protein
64
MP 252.57 286.62 X Gain 3.8 g MP/kg BW.75
65
Net Protein Required for Production
Amino Acids Proteins Milk kg/d (Milk
yield, kg/d) ( protein in milk) Growth g/d
SWG (268 - (29.4 (RE/SWG))) SWG Shrunk weight
gain, kg/d RE Retained energy, Mcal/d RE
obtained from net energy equations.
66
Efficiency of Utilization ofMetabolizable
Protein for Deposition of Net Protein
1. Growth Beef NRC If EQEBW lt 300 kg 0.834
(0.00114 x EQEBW) Otherwise 0.492 Dairy NRC If
EQEBW lt 478 kg 0.834 (0.00114 x
EQEBW) Otherwise 0.289
67
Efficiency of Utilization ofMetabolizable
Protein for Deposition of Net Protein
2. Lactation Protein in milk/0.65 (Beef
NRC) Protein in milk/0.67 (Dairy
NRC) 3.Pregnancy See equations in publications
68
Growth of Cattle Change in Body Composition
ISU experiments
69
Protein Requirements of Growing CattleChanges
with Increase in Weight
70
Example CalculationLevel 1
300 kg steer Gaining 1.37 kg SBW/d 10.7 protein
in gain Consuming 6.8 kg feed DM 11.5 crude
protein, 30 UIP 80 TDN Is this steer being
fed adequate protein?
71
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 requirement 273.9
293.2 567.1 g/d
72
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 supplied 187.7 452.6
640.3 g/d Requirement 567.1 Supply
640.3 Conclusion Steer has adequate dietary
protein
73
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
74
Consequences of Shortage of DIP
Synthesis of bacterial protein is limited 547.4 g
rather than 707.2 547.4 (.8) (.8) 350.3 g MP
from microbes 350.3 187.7 538.0 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
75
How Can Rumen AvailableNitrogen be Increased?
Feed more degradable protein Usually expensive to
do so unless more MP is also needed Feed
nonprotein nitrogen such as urea All is degraded
to NH3. Usually cost is least Does more DIP
have to be added? Models indicate yes
76
Supplementing Ruminal Available Nitrogen
Urea (300/ton) 159.8/2.8 57.1 g/d of urea
could be added Urea is 280 crude protein Cost
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/d Cost 473.5 x 0.00022 0.1043/d Dry DGS
(80/ton) (159.8/0.5)/0.3 1065.3 g/d Cost
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
77
Supplementation of Diets with Urea
If inadequate DIP is available for synthesis of
BCP, need to add degradable N Can add urea Urea
Fermentation Potential (g urea/kg diet DM) UFP
(BCP, g/kg - DIP, g/kg)/2.8 kg kg diet DM 2.8
Urea is 280 crude protein UFP Inadequate
DIP, urea will benefit - UFP There is surplus
DIP, urea of no benefit
78
Feed Values Beef NRC
79
Protein Values for Feeds
80
What is The Requirement for DIP? Finishing Cattle
Cooper et al. JAS 2002 Fed different
concentrations of urea to finishing steers Diets
Dry rolled, high moisture and steam flaked
corn Measured feed intake and gain Estimated
requirement for DIP (DIP as of diet DM) Dry
rolled 6.3 High moisture 10.0 Steam flaked
9.5 High moisture and steam flaked corns more
digestible in the rumen Increased microbial
protein production Limitations Protein
requirements change during the experiment
81
Programmed Feeding of Supplemental
ProteinFeedlot Steers - ISU
82
Programmed Feeding of Supplemental Protein740 lb
Feedlot Steers
83
What is The Requirement for DIP?Conclusions

• All of calculated DIP does not have to be
  satisfied
• when MP is being fed in excess
• Enough nitrogen is recycling
• Reduces quantity of nitrogen fed

84
If Diet Needs More Metabolizable Protein
First consideration Can microbial protein be
increased? If short of ruminal available N Add
urea Provide ammonia to microorganisms If surplus
of rumen available N Add fermentable feed
(TDN) Provide energy to microorganisms Second
consideration Supplement diet with less
degradable protein
85
Application of Metabolizable Protein System to
Feedlot Cattle

• Supplement protein in relation to requirement
• Optimize performance
• High performing cattle
• Phase feed supplemental protein
• Change supplement in relation to rate and
• composition of gain
• Use computer programs
• Supplement to minimize environmental impact

86
Protein Requirements of Growing CattleRelation
to Rate of Gain
87
Increased Protein RequirementsRuminants
Situation Consequences 1. Young
animals Leaner gain Fast rate of gain
More total protein Leaner gain in
tissues 2. Compensatory gain Greater muscle
growth 3. High levels of lactation More milk
protein 4. Hormone implants and bGH More protein
synthesis 5. Low feed intakes Less MP from diet
High energy diets and microbes Need to
feed higher concentrations of protein or less
degradable protein
88
Effects of Feeding Soybean MealFeedlot Steers
Yearling steers, Revalor implants At high
rates of gain, cattle respond to bypass protein.
89
Effects of Feeding More Urea
Yearling steers, Revalor implant If DIP
requirement is met, no response to feeding more
urea.
90
Effects of Level of Soybean MealFed to Feedlot
Steers
Yearling steers, Revalor implants Greatest
response to first addition of bypass protein.
91
Changing SBM Supplement to Urea Phase Feeding
Yearling steers, Revalor implant Cattle
require less protein as they approach mature
finished weights Industry standard is 13.5 to 14
crude protein for finishing cattle
92
Nitrogen Balance - Feedlot Steers680 to 1377
lbs Implanted and fed 14 crude protein
Cattle retain 10 to 15 of dietary N during
finishing.
93
Phase Feeding of Protein830 lb Steers
0 to 61 days 0 to 130 days
11.0 14.0 14.0 11.0 14.0
11.0
94
Diets to Feed in a Phase ProgramTheoretical
Feeding Program
Crude protein Corn 9.0, Hay 16.0
95
Rumen Degradable and Metabolizable Protein
Theoretical Phase-Fed Diets
Diet I II III
III III
Nitrogen excreted from 10,000 head feedyard
312.9 tons
96
Develop Diets with Low Protein Ingredients Reduce
Nitrogen Excretion
Crude protein Corn 6.0, Hay 10.0
97
Rumen Degradable and Metabolizable Protein in
Phase-Fed Diets
Diet I II III IV
IV
Nitrogen excreted from 10,000 head feedyard 283
tons
98
Response to Feeding UreaKSU Study
99
Response to Feeding UreaFinishing Steers
KSU, 1997 - 730 lb steers fed 154 days. Diet Dry
rolled corn and 10 prairie hay.
100
Response to Implants and Protein700 lb Steers
0 to 85 days 86 to 186 days
--No Implant-- --------Implant-------
No Implant -----Implant-----
101
Effect of Implants on Nitrogen Retention Feedlot
Steers
102
Protein Requirements of Lactating Cows
103
Protein Requirements of Dairy Cows
Milk yield Composition of milk Body
weight Maintenance Body weight change Pregnancy
104
Meeting Dairy Cows Protein Requirement

• Feed intake
• Nature of feed ingredients
• Fermentable energy
• Microbial 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

105
Recommendations for Feeding High RUP Byproducts
to Dairy Cows
106
Digestibility of RUPDairy NRC
107
Why Limit High RUP Proteins?Lactating Cows

• Animal byproducts tend to reduce feed intake
• Palatability
• Fat content (Fish meal decreases milk fat)
• Decreased feed intake reduces
• microbial protein synthesis
• Plant byproducts may have poor amino acid
• balance
• Corn proteins deficient in lysine and tryptophan
• Digestibility of RUP (UIP)
• Might create a deficiency of RDP (DIP)
• Quality of RUP proteins can be variable

108
Why a Variable Response to RUP?Lactating Cows

• Protein requirements may have been met
• Protein might not be first limiting
• Cows mobilizing body proteins
• First limiting amino acid might not be increased
• Amino acid ratios of metabolizable protein
• Digestibility of RUP
• Use of RUP might cause a shortage of RDP
• Overestimation of degradation of other
• supplemental proteins