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• www.dam.mihanblog.com

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• Volatile Fatty acid VFA
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• ??????? ???? ?? ??? ?? PK ???? ????? ????? ? 4.7
  ? PK???? ????????? 4.87 ???. ????? ??? ?? PH ???
  6 ?? 7 ?? ?? ??? ????? ?? ???? ????? ?????? ??
  ??? ????? ? 87 ?? 97 ???? ???? ????? ? ????
  ????????? ? ??????? ?? ??? ???? ????? ? ?? ???
  ??? ?? ?? PK ?????? ?????? ??? .

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Cellulose Fibrobacter Cellulose
fragments succinogenes Succinate
Acetate Formate Selenomonas
ruminantium Lactic acid
Propionate Acetate Formate
H2 Megasphaera elsdenii Prop
ionate Acetate H2
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Glucose Pyruvate CO2 Formate Lactate O
xaloacetate 2H Acetyl-CoA Malate
Acrylate Fumarate Acetoacetyl
CoA Succinate Methane Acetate Butyrate
Propionate Succinyl CoA Propionyl CoA
Methylmalonyl CoA
Co Vit B12
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????? ???? ?????
1. Pyruvate-formate lyase Pyruvate Acetyl
COA Acetate Formate 6H CH4 2H2O 2.
Pyruvate oxidoreductase (Most common pathway)
FD FDH2 (Flavin adenine
dinucleotide) Pyruvate Acetyl COA Acetate CO2
3 carbon 2 carbon
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AcetylCoA Acetyl-P ADP
Phosphotransacetylase Acetate kinase ATP
Acetate
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????? ???? ?????????
1. ???? ???????? ?? ?? ?????????? ????
60 ????? ????????? ?? ??? ????
ATP Pyruvate Oxaloacetate Malate CO2 A
DP Fumarate NADHH Propionly
COA Succinate NAD Propionate Methylmalonly
COA Succinyl COA Co Vit B12
Pyruvate carboxylase
Uses H
3 carbon
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2. ???? ??????? NADH NAD Pyruvate Lactic
acid Acrylyl COA
NADHH Propionate NAD Propionyl
COA ??? ???? ?? ????? ?? ???? ?? ?????? ? ????
????? ?? ??? ??? ?? ???
Uses H
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FD FDH2 CO2
Pyruvate Acetyl COA Acetaldyhyde CO2 COA
Acetoacetyl CoA Ethanol Malonyl COA
NADHH Acetyl CoA NAD COA
B-hydroxybutyryl COA Crotonyl COA
NADHH Butyryl COA NAD Acetate Butyrate
Butyrate-P Acetyl COA
3 carbon
ATP ADP
4 carbon
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????? ?????
????? ???? (High grain) Glucose 2 Acetate
2 CO2 8 H Glucose Butyrate 2 CO2 4
H Glucose 2 Propionate 2 O CO2 8 H
CH4 2 H2O
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????? ?????
????? ???? (High forage) 3 Glucose 6
Acetate 6 CO2 24 H Glucose Butyrate 2
CO2 4 H Glucose 2 Propionate 2 O 3
CO2 24 H 3 CH4 6 H2O
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?????
????? ?? Net 3 Glucose 2 Acetate Butyrate 2
Propionate 3 CO2 CH4 2 H2O
(AcetatePropionate 1 Methaneglucose
.33) ????? ???? Net 5 Glucose 6 Acetate
Butyrate 2 Propionate 5 CO2 3 CH4 6
H2O (AcetatePropionate 3
MethaneGlucose .60)
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??? ???? ?? ???? VFA
ForageGrain -----Molar ratios----- Acetate
Propionate Butyrate 1000 71.4 16.0
7.9 7525 68.2 18.1 8.0 5050 65.3
18.4 10.4 4060 59.8 25.9
10.2 2080 53.6 30.6 10.7
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Effects of Rumensin on Rumen Propionate
Propionate production
moles/day Roughage 5.96 Roughage
Rumensin 8.91 Concentrate
6.89 Concentrate Rumensin 12.15
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• 70 of VFA absorbed from rumen-reticulum
• 60 to 70 of remainder absorbed from omasum
• Papillae are important provide surface area
• Absorption increases at lower pH
• H Ac- HAc

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??? VFA??? Ac-
?????
Ac- Ac- HAc ??? ??????? H
Metabolism HCO3- H2O H2CO3
CO2 CO2 Carbonic Metabolism anhydras
e HAc HAc
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??? ???? ??? ??? ????
???? ??? Butyrate
gt Propionate gt Acetate ???? ???? ???? ??? ??? ??
????? ????? ???? ??? ????? ??? . ???? PH ?????
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???????? ?? ?? ???? ??? ???? ?? ????? ??? ???
????? ??? . ?? ?? ???? ????? ????? ??? ?????
?????? ?????? ???? Lower pH Growth of papillae
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Metabolism of VFA by GIT
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???????? ????? ?? ??? . ?- hydroxybutyric acid
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????? ?? ???? ?????? ?? ??? . ?????? ?? ????? ??
????? ????? ?? ?????? ????? ??????? ?? ??? .
VFA ? ???????? ??? ???? ???? ?????? ??? ?? ???
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Tissue Metabolism VFA
VFA GIT tissues Liver Body tissues Use
of VFA Energy Carbon for synthesis Long-chain
fatty acids Glucose Amino acids Other
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Utilization of Acetate in Metabolism
1. Acetate (As energy) Energy Acetate
Acetyl CoA Krebs cycle 2 CO2 2
carbons (10 ATP/mole) 2. Acetate (Carbon
for synthesis of fatty acids in adipose)
Acetate Acetyl CoA Fatty acids Lipids
HNADPH NADP Glycerol Pentose
PO4 CO2 shunt Glucose
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Propionate Propionate Propionyl CoA
Methylmalonyl CoA CO2 Succinyl
CoA Vit B12 Glucose Krebs cy
cle 2 CO2 Energy (18 ATP/mole)
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????? VFA ?? ????????? ?????
Acetate Energy Carbon source for fatty
acids Adipose Mammary gland Not used for net
synthesis of glucose Propionate Energy
Precursor of glucose Butyrate Energy Carbon
source for fatty acids - mammary
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??? VFA ?? ????? ??? ???? ???
Propionate ?????? ????? ??? ????? ???? ????
??????? Butryate ?? ???? ????? ??????? ??? ???
????? ???? ???? ??????? ????? ???? ????
???????? ?????? ????? ??? Acetate ?? ????
????? ??????? ??? ??? ??????? ?? ?????? ??? ???
Glucose ?????? ???? ???? ???????
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• 1- ????
• 2- ???? ?? ????? ???? ??? ??? ???? ???? ??? ????
  ? ?????? ? ????? ??
• 3- ??? ????? ???

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ATP/mole Energy in ATP ?????
?????? (kcal/mole) Acetate 10
76.0 36.3 Propionate 18 136.8
37.2 Butyrate 27 205.2 39.1
Glucose 38 288.8 42.9
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Sources of Glucose CarbonRuminants
Ruminants dependent on gluconeogenesis for major
portion of glucose Sources of glucose in
metabolism 1. Propionate 2. Amino acids 3. Lactic
acid 4. Glycerol 5. Carbohydrate digestion in
intestine Absorption of glucose from intestine
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Reference

• Farm animal nutrition and metabolism

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