Rumen
Transformations
of Lipid
Tom Jenkins, Professor
Department of Animal &
Veterinary Sciences
Rumen Transformations of Lipid
Review of Dietary Lipid
 Fatty acids are most important lipid fraction.
 Majority of fatty acids are bound to glycerol as simple or
compound lipids.
 Majority of fatty acids are unsaturated.
Rumen Transformations of Lipid
Learning Objectives
 What happens to dietary lipid as it passes from the diet to
the intestines and is metabolized by rumen
microorganisms?
 What are the intermediates and end products that
accumulate in the rumen from lipid metabolism?
 How does lipid transformations in the rumen affect animal
performance?
Rumen Transformations of Lipid
Compounds Extracted in Fat Test?
Simple
Lipolysis
Compound
PUFA
Biohydrogenation
MUFA
Microbial Lipid Synthesis
VFA
Rumen Transformations of Lipid
How Does Dietary Lipid Change
as it Passes Through the Rumen?
47.9 lb. DMI
60% Forage
(mainly corn silage,
5 lbs. alfalfa hay)
From CPM for Dairy v.3.0.8
Rumen Transformations of Lipid
Rumen FA Transformations
Intake
Outflow
892 g FA
(<10%
FFA)
876 g FA
2 g C18:0
Small
Intestine
Esophagus
Reticulum
Rumen
Omasum
Abomasum
Large
Intestine
Rumen
C18:0
C18:1
219 g
C18:1
C18:2
440 g
C18:2
C18:3
From CPM for Dairy v.3.0.8
37 g C18:3
Rumen Transformations of Lipid
Biohydrogenation
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
H
H
H
H
H
H
H
H
H
H
H
H
Unsaturated (18:2)
Stearic (18:0)
H
O
C
OH
Rumen Transformations of Lipid
Biohydrogenation
Unsaturated Fat
H
H
H
H
H
C
C
C
C
C
H
H
H
Rumen Transformations of Lipid
Biohydrogenation
H
H
H
H
H
C
C
C
C
C
H
H
H
H
H
Rumen Transformations of Lipid
Biohydrogenation
Saturated Fat
H
H
H
H
H
C
C
C
C
C
H
H
H
H
H
Rumen Transformations of Lipid
Biohydrogenation
Unsaturated (18:2)
CLA (18:2)
trans (18:1)
Stearic (18:0)
Rumen Transformations of Lipid
Biohydrogenation
Unsaturated Fat
H
H
H
H
H
C
C
C
C
C
H
Rumen Transformations of Lipid
Biohydrogenation
H
H
H
H
H
C
C
C
C
C
H
H
Rumen Transformations of Lipid
Biohydrogenation
CLA
H
H
C
C
H
C
H
H
H
C
C
Rumen Transformations of Lipid
CLA Intermediates in Digesta
Linoleic (18:2)
cis–9 trans–11 (18:2)
60
50
40
30
20
10
0
% of total
t7t9
t8t10
t9t11
t10t12
t11t13
t12t14
t7c9
t8c10
c9t11
t10c12
t11c13
c11t13
100
80
trans–11 (18:1)
60
40
20
Stearic (18:0)
0
From Teter, B.B., and T.C. Jenkins. 2006. In Advances in Conjugated Linoleic Acid Research, Vol. 3
c12t14
Rumen Transformations of Lipid
Point 1–Diet Can Change BH
Linoleic Acid (cis–9, cis–12 C18:2)
Altered Pathways
Conjugated Linoleic Acid
(cis–9, trans–11 CLA)
Conjugated Linoleic Acid
Isomers
trans–11 C18:1
trans–C18:1 Isomers
Stearic (C18:0)
Stearic (C18:0)
Rumen Transformations of Lipid
Point 2
MINOR intermediates of biohydrogenation can
have MAJOR effects on animal performance and
human health
Rumen Transformations of Lipid
Impact of Rumen Lipid Metabolism
 Affects human health
 Meat and milk higher in saturated fat
 Bioactive metabolites
 Anti-carcinogenic
 Anti-atherogenic
 Enhance immune system
Rumen Transformations of Lipid
Impact of Rumen Lipid Metabolism
 Affects animal performance
 Supply of essential fatty acids– reproduction
 Fatty acid antimicrobial effects– production
 Bioactive metabolites
 Milk fat depression
Rumen Transformations of Lipid
Question
Match each of the below from the list of answers shown on the
right. One answer per blank.
1. ___ Abbreviation of the major fatty acid
consumed by dairy cows
2. ___ Increases FFA in rumen contents
3. ___ Abbreviation of the CLA normally
produced in the rumen
4. ___ Greatly reduces the supply of
essential fatty acids to body tissues
A. Biohydrogenation
B. cis–9, trans–11 18:2
C. Lipolysis
D. cis–9, cis–12 18:2
E. trans–11 C18:1
F. Peroxidation
Rumen Transformations of Lipid
Question
Which of the below is the best substrate for the synthesis of
CLA in the rumen?
A. Omega–9 fatty acids
B. Essential fatty acids
C. Saturated fatty acids
D. None of the above
Rumen Transformations of Lipid
Questions & Answers
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