Meeting the Amino Acid Needs of the Transition Cow
Thomas R. Overton, Ph.D. Associate Professor of Animal Science Director, PRO-DAIRY Cornell University RP Feed Components Post-Conference Symposium Penn State Dairy Nutrition Workshop
Metabolizable protein and amino acids Clearly an ongoing opportunity area in ration formulation and implementation for transition cows
1
A few key questions • What are the dynamics of protein and AA metabolism in the transition cow? • What “special” requirements for amino acids are present in the transition cow? • What are metabolizable protein targets for prepartum cows and why do we need to balance for MP? • What have been the responses to AA balancing in the transition cow?
2000 1800 1600 1400 1200 1000 800 600 400 200 0
30 25 20 M c a l/d
g /d
Comparison of estimated demands for nutrients at 250 d of gestation and 4 d of lactation by the gravid uterus (light blue) and mammary gland (dark blue)
15 10 5 0
Glucose
Amino acids
Fatty acids
Net energy
Adapted from Bell, 1995
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Amino acid pools (adapted from slide courtesy Dr. Sarah Boucher) Body protein Synthesis
Metabolizable protein
Degradation
Amino acids N&C
Milk protein
Synthesis Nonprotein derivatives
Glycogen Glucose
Ammonia & urea
TCA cycle intermediates
CO2 + Energy
Fatty acids
Bell et al., 2000
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Cows mobilize some body protein during early lactation (Komaragiri and Erdman, 1997) • Measured body composition in Holsteins at -2, 5, and 12 wk relative to calving using D2O dilution technique • Maximum loss of body tissue occurred between 2 wk before calving and 5 wk postpartum – 54 kg of body fat – 21 kg of body protein
• From 5 wk to 12 wk postpartum – 18 kg of body fat – No change in body protein
• Protein mobilization was not affected by protein level in diet (16% CP with 6% RUP vs. 19% CP with 9% RUP)
R atio o f 3-m eth yl h istid in e to creatin in e (n m o l:m g )
Skeletal muscle protein degradation rate increases during early lactation 100 80 60 40 20 0 -35 -21 -14 -10
-7
-3
1
3
7
10
14
21
35
65
Day relative to parturition High grain, ad lib
High grain, restricted
High fat, ad lib
High fat, restricted
Overton et al., 1998; Day, P < 0.001
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A few key questions • What are the dynamics of protein and AA metabolism in the transition cow? • What “special” requirements for amino acids are present in the transition cow? • What are metabolizable protein targets for prepartum cows and why do we need to balance for MP? • What have been the responses to AA balancing in the transition cow?
“Special” requirements for AA during the transition period • Role in gluconeogenesis and meeting overall glucose needs of the cow during early lactation • Specialized needs for specific AA (e.g., Met and Lys) in aspects of liver metabolism
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4000 3500 3000 2500 Glucose, 2000 g/d 1500 1000 500 0
Pred. required Pred. supply Actual supply -19 -11 11
22
33
83
Day relative to calving Predicted whole-body glucose requirements compared with predicted and actual supply of glucose by gut and liver during the transition period and early lactation. Data are from Reynolds et al., 2003 and predictions are as described by Overton (1998).
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Contribution, %
70 60 50 40 20
Lactate Propionate Glycerol
10
Amino acids
30
0 -19
-11
11
22
33
83
Day relative to calving Maximum contributions of lactate, propionate, and glycerol and minimum calulcated contributions of amino acids to liver glucose release during the transition period and early lactation (From Reynolds et al., 2003).
Data of Overton et al., 1998 in Bell et al., 2000
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Contribution, g/d
2000 1500 1000 500 0 -19
-11
11
22
33
83
Day relative to calving
Minimum contribution of metabolizable protein to glucose supply during the transition period and early lactation.
Summary -- use of amino acids for glucose during transition period • All amino acids except for leucine and lysine can make a net contribution to glucose synthesis • Utilization of amino acids for gluconeogenesis also is generally supply dependent • Amino acids mobilized from skeletal muscle likely make a substantial contribution to glucose synthesis postcalving • Don’t understand regulation of mobilization • Likely that AA are an important substrate for gluconeogenesis and adaptation to lactation in the cow
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“Special” requirements for AA during the transition period • Role in gluconeogenesis and meeting overall glucose needs of the cow during early lactation • Specialized needs for specific AA (e.g., Met and Lys) in aspects of liver metabolism
Hepatic lipid metabolism Adipose tissue
CO2
ketone bodies
triglycerides
MITOCHONDRIA
fat mobilization
FABP
NEFA TAG-rich lipoproteins
CYTOPLASMIC POOL (storage)
Acetyl CoA ATP
FFA
CPT I
triglycerides
acyl CoA
phospholipids
acetate
cholesterol
VFA
SER glucose
glycerol 3-P
lipids
MTP
cholesteryl esters free cholesterol
MICROSOMAL POOL (secretion)
NUCLEUS
diet
Blood compartment
VLDL
SECRETORY VESICLES
apo B gene
SER apo B mRNA
GOLGI APPARATUS
Blood compartment
apo B RER
apo B catabolism
Bauchart et al., 1998
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Factors affecting synthesis of VLDL • Methionine may be required for sufficient synthesis of apoprotein B • Infusion of methionine plus lysine increased hepatic balance of VLDL (Durand et al., 1992) • Methionine is involved in de novo synthesis of choline • Phosphatidylcholine is required for synthesis of VLDL
Potential site of involvement of increased methyl/specific AA supply on mitochondrial fatty acid oxidation
• Synthesis of carnitine (trimethylation of lysine with SAM) -- essential for transport of acyl-CoA into mitochondria for B-oxidation • Incubation of bovine liver slices with carnitine in vitro increased conversion of radiolabeled palmitate to CO2 (Drackley et al., 1991)
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Interrelationships of methionine, betaine, and choline in liver metabolism Cysteine Biosynthesis
Protein Synthesis
Methionine Fat Metabolism Methyl Donation Choline Betaine
Acetyl Choline Synthesis Cell Membrane Structure
A few key questions • What are the dynamics of protein and AA metabolism in the transition cow? • What “special” requirements for amino acids are present in the transition cow? • What are metabolizable protein targets for prepartum cows and why do we need to balance for MP? • What have been the responses to AA balancing in the transition cow?
11
Overall goals for energy and metabolizable protein intake of both far-off and close-up cows • Far off cows (dry off until ~ 3 weeks precalving) – ~ 15 - 17 Mcal of NEL per day – 110 to 120% of ME requirements – ~ 1000 g/d of metabolizable protein • Close-up cows (last 3 weeks before calving) – ~16 - 18 Mcal of NEL per day – 110 to 130% of ME requirements – ~ 1100 to 1200 g/d of metabolizable protein • Vary energy density of diets based upon group DMI – Which means have to know DMI to know how much to “bulk up” the diet – Almost want to achieve the above in the largest DMI package that cows will consume consistently
Considerations for protein formulation of close-up diet
NRC (2001) Minimum requirement for metabolizable protein of example close-up heifer and cow ~ 900 g/d Does not include mammogenesis • (VandeHaar and Donkin, 1999; Bell et al., 2000)
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Mammogenesis in CNCPS • Based upon Bell et al. (2000) and VandeHaar and Donkin (1999) • “Switch” is turned on from 259 days of pregnancy until 21 days of lactation • Assumes 80 grams of NP deposition in mammary gland and efficiency of use of 29% • Result for MP is additional requirement of ~277 g/d
Considerations for protein formulation of close-up diet
NRC (2001) Minimum requirement for metabolizable protein of example close-up heifer and cow ~ 900 g/d Does not include mammogenesis • (VandeHaar and Donkin, 1999; Bell et al., 2000)
Inclusion of estimate for mammogenesis increases metabolizable protein requirement to ~ 1100 to 1200 g/d
If adequate attention to carbohydrate and protein fractions (RUP vs. RDP), metabolizable protein requirement can be met with a diet containing 12 to 15% CP
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Considerations for protein formulation of close-up diet
NRC (2001) Minimum requirement for metabolizable protein of example close-up heifer and cow ~ 900 g/d Does not include mammogenesis • (VandeHaar and Donkin, 1999; Bell et al., 2000)
Inclusion of estimate for mammogenesis increases metabolizable protein requirement to ~ 1100 g/d
If adequate attention to carbohydrate and protein fractions (RUP vs. RDP), metabolizable protein requirement can be met with a diet containing 12 to 15% CP
CP content beyond 15% of DM is not advantageous and may be detrimental
(Putnam et al., 1999; Hartwell et al., 2000; Park et al., 2002; Hayirli et al, 2002)
Why do we need to balance for MP? • Well-known academic – 1998 ADSA Discover Conference on transition cows – “The industry will not balance for MP until it is printed on a forage analysis”
• MP is a much better reflection of protein supply to the cow than is CP – Especially when implementing controlled energy/lower energy dry cow diets
• Need to be conscious of excess N in immediate periparturient period (liver metabolism)
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Relationships between supplies of crude protein and metabolizable protein predicted using CPM Dairy Expt.
CP, %
CP, g/d % change
MP, g/d % change
Putnam and Varga, 1998
10.6
1166
---
1015
12.7
1422
22.0
1083
6.7
14.5
1638
40.4
1135
11.8
13.3
1357
---
17.8
1887
39.0
14.4
1469
---
13.2
1716
16.8
Putnam et al., 1999a
Minor et al., 1998
985 1121
892 1177
---
--13.8
--32.0
Liver triglyceride concentrations (% of wet weight) during the transition period 18 16 14 12 10 8 6 4 2 0 -21
1
21
Piepenbrink and Overton, 2000
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Consequences of increased liver TAG content • Impaired gluconeogenic capacity from propionate – Cadorniga-Valino et al., 1997 – Piepenbrink et al., 2003 • Impaired ureagenic capacity – Strang et al., 1998 – Zhu et al., 2000 • Impaired capacity to clear bacterial endotoxin – (Andersen et al., 1996) • Delayed onset of estrous cycling and impaired reproductive performance (associated with increased liver triglyceride; Jorritsma et al., 2003)
Effect of intracellular lipid infiltration by preexposure to oleate and concurrent presence of oleate on the rate of propionate conversion to glucose. 2.5
O mM oleate 2 mM oleate
2 1.5 1 0.5 0 Noninfiltrated
Lipid infiltrated
Cadorniga-Valino et al., 1997. J. Dairy Sci. 80:646-656.
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Correlation of concentration of hepatic TAG and r
P
Glycogen d +1
-0.24
