Stephen B. Smith
Department of Animal Science
Texas A&M University
The Main Points of This
Presentation
 Certain
production systems
promote the development of
marbling in beef cattle.
 A limited number of breed types
seem to marble well even when
fed limited amounts of
concentrate.
The Importance of Oleic Acid
 Beef
palatability is positively correlated
with the amount of oleic acid in beef.
 Asian markets prefer beef that contains
elevated oleic acid (softer fat).
 Oleic acid has positive health benefits.
 The concentration of oleic acid is
positively correlated with marbling
scores.
Monounsaturated:Saturated Fatty Acid
(MUFA:SFA) Ratios in Ground Beef




Grass-fed beef
MUFA:SFA ratios are
approx. 0.70.
The cheapest ground
beef has MUFA:SFA
ratio around 0.9.
Angus-branded
products have
MUFA:SFA ratios
over 1.2.
Wagyu ground beef
has a ratio of 1.4.
Overview of marbling development
USDA Choice
Japanese B5
Marbling is composed of fat cells
that lie between muscle fibers.
Marbling
adipocytes
Muscle
fibers
Moody and Cassens, 1968
Differentiation of preadipocytes is
accompanied by an increase in stearoyl-CoA
desaturase (SCD) gene expression.
Chung et al., 2007
CLA t10,c12 strongly inhibited SCD gene
expression, but CLA c9,t11 was without effect.
Marbling Adipocyte Differentiation
SCD gene expression
increases.
Proliferation
Fibroblasts
Preadipocytes
Mature adipocytes
Adipose tissue growth and fatty acids
8 mo old –
High in
saturated fat
16 mo old High in oleic
acid
12 mo old
More oleic
acid, less
saturated
fat
What production factors influence
oleic acid and trans-fatty acid
concentrations?
Feeding grain-based diets elevates oleic
acid and depresses trans-fatty acid
concentrations.
 Increasing time on feed elevates oleic acid
and decreases trans-fatty acid
concentrations.

Feeding corn increases oleic acid and
decreases trans-fatty acids.
Smith et al. 1998
Archibeque et al. 2005
Chung et al. 2006
12
Corn feeding
stimulates stearoylCoA desaturase
(SCD) gene
expression.
 Corn feeding
depresses the
production of transfatty acids in the
rumen.

Vaccenic acid (18:1trans-11)
10
8
6
4
2
0
20
25
30
35
40
45
Oleic acid (18:1n-9)
50
55
60
Increasing Oleic Acid in Beef
Strategies: Genetics and Production
We use either
good quality
Angus or
American Wagyu.
Low-oleic
Pasture-fed
Mid-oleic
Corn-fed to market weight
High-oleic
Corn-fed, long-fed
Comparisons of Angus and American
Wagyu steers.
Angus steers
consistently
produce highquality beef.
 Wagyu steers
are known for
their ability to
marble.

Japanese Black cattle are derived from the
Korean Hanwoo.
J. Black
Korean Black Hanwoo
Both breed types are
highly marbled and
their beef is high in
oleic acid.
Korean Hanwoo
Most of what I
know about J.
Black cattle I
learned from
Dr. Meiji
Zembayshi.
Feeding high concentrate at the end
of production increases marbling in J.
Black cattle.
Dr. Zembayashi
described
differences
between J. Black
and other breed
types raised in
Japan.
Cattle containing J. Black genetics contain
more marbling than other breed types.
There seems to be no limit to the
amount of marbling in J. Black cattle.
Percentage intramuscular lipid
30
20
B
BHo
BBHo
RBHo
CBHo
NBHo
10
0
400
600
800
Slaughter age , d
1000
1200
Japanese Black cattle have the highest
percentage oleic acid in their fat.
75
“Marbling and fat composition are 60% genetics
and 40% production.” Shogo Takeda, Takeda
Farm Co., Ltd, Hokkaido, Japan
Percentage
70
65
---Fed for 550 days---
60
55
Fed for 150 days
50
45
J. Black
Wagyu
Angus
Cattle type
Angus X Hereford
Higher marbling scores are associated
with more monounsaturated fatty acids.
Short-fed cattle
are low in marbling
(%IML) and
MUFA.
 Long-fed cattle are
high in marbling
and MUFA.
 This is caused by
corn in the diet.

Finishing diets:
Corn-based diet





89.1% dry matter
11.2% crude protein
NEm = 1.81 Mcal/kg
NEg = 1.19 Mcal/kg
Target = 1.36 kg/d
ADG.
Hay-based diet


Steers had free
access to hay and
pasture.
Corn diet was added
to provide 0.9 kg/d
ADG.
Angus and
Wagyu steers
were fed cornor hay-based
diets.


Cattle were
sampled at 500 or
600 kg BW.
Hay-fed steers
were fed an
additional 4 mo to
match the body
weights of the
corn-fed steers.
Body weights
for corn- and
hay-fed Angus
steers were
identical.
Corn-fed Wagyu
steers grew
more slowly
than predicted.
At 600 kg, hayfed and cornfed steers were
at the same
body weights.

Therefore, all
comparisons
can be made
at equal body
weights.
Corn- and Hay-fed Angus and Wagyu
Steers



Marbling
increased with
body weight.
Wagyu steers
had higher
marbling scores
than Angus
steers.
Corn-fed steers
had higher
marbling scores
than hay-fed
steers.
SCD gene expression
in s.c. adipose tissue
was depressed in the
hay-fed Angus steers,
but increased over
time in the Wagyu
steers.
MUFA:SFA Ratio and Body Weight



The MUFA:SFA
ratio increased
with body weight.
Wagyu steers had
higher MUFA:SFA
ratios than Angus
steers.
Corn-fed steers
had higher
MUFA:SFA ratios
than hay-fed
steers.
Factors Influencing Lipid Melting
Points
Melting points of beef
lipids decrease with
time on feed.
 Corn feeding reduces
melting points.

 Less stearic and trans-
vaccenic acid is absorbed
from the rumen.
 There is greater desaturase
activity in adipose tissues,
so there is more oleic acid.
Calf-feeding and yearling-feeding
When corn is inexpensive or there is not
good pasture, producers feed corn to
calves as soon as they are weaned.
 When corn is expensive or there is good
pasture, producers background their
calves on pasture until they are yearlings
(12 mo of age).

Carcass and fatty acid composition of
calf-fed and yearling-fed Angus steers




Calf-fed steers were fed
a corn-based diet at
weaning at 8 mo
Yearling-fed steers
grazed on pasture until
12 mo of age.
At 12 mo of age,
yearling-fed steers were
fed the corn-based diet.
Steers were sampled at
the same time on feed
and same body weights.
Fat thickness and marbling scores
Fat over the loin was higher
in calf-fed steers at 12 mo of
age.
Marbling scores also were
higher in calf-fed steers at 12
mo of age.
SCD mRNA and MUFA in s.c. fat
SCD mRNA in s.c. fat was
higher in calf-fed steers at 12
mo of age.
The s.c. fat MUFA:SFA ratio
also was higher in CF steers at
12 mo of age.
SCD mRNA and MUFA in marbling fat
SCD mRNA in marbling was
higher in calf-fed steers at 12
mo of age.
The marbling MUFA:SFA ratio
was depressed in yearling-fed
steers.
Conclusions:
Increasing the amount of marbling in
beef is related to fatty acid composition
of beef.
 Only a limited number of breed types will
marble well on high-roughage, lowconcentrate diets.
