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Physiology of MarblingSusan K. Duckett
Clemson University
Marbling
Choice-Upper Choice,
CABSelect
Prime
National Beef Quality Audits
2016 vs. 1993
+64% Prime
+75% Upper Choice (CAB)
-35% Select
-86% Standard
71% Choice 55%
Choice
Why?
DISCOUNTS and premiums
Marbling h2 = 0.48Carcass EPDs
Choice – Select Spread
Choice – Select Spread$2 - $25/cwt differential
Avg. HCW = 879 lb$18 - $220/carcass loss
Graph taken from CAB Insider, May 2 2018
Premiums and Incentives
CAB (Upper Choice):$4-14/cwt premium
PRIME:$9-26/cwt premium
Current Market
Base Price: Ch YG 3$202.60/cwt
Premiums:Prime 1-3 $13.80/cwtCAB 1-3 $5.28/cwtYG 1 $3.86/cwt
Discounts:Select $-13.65/cwtStandard $-29.77/cwtYG 4 $-11.21/cwt
Historical Model of Marbling Deposition
• Marbling:• Last to be deposited and First to be mobilized
IMF
Hood and Allen, 1973, J. Lipid Res. 14:605-609
Marbling, intramuscular
Backfat, subcutaneous
Du et al. 2015. Meat Sci. 40-47
Recent Models of Marbling Deposition
IMF Fractional Growth Rate
Bruns et al. 2004. JAS 82:1315-22
Hot carcass weight, lb450-550 550-650 650-748 748-849
Can we Accelerate Marbling Deposition?
Creep Feeding
Creep Feeding -
0
100
200
300
400
500
600
Pasture Drylot, nocreep
Drylot,creep
Control Limitedcreep
(1kg/d)
Unlimitedcreep
Corn Soybeanhulls
Mar
blin
g sc
ore
, 50
0 =
Sm
all
Deutscher/Slyter Faulkner
a
c
b
* * *
Deutscher and Slyter, 1978, JAS 47:19-28. SD, 6 yrFaulkner et al. 1994. JAS 72:470-477. Illinois
Creep Feeding -
0
10
20
30
40
50
60
70
80
90
EW NW + creep NW
%
low Choice UpperChoice Prime
Myers et al. 1999. JAS 77:300-310. Illinois
93%a
>Modest
68%b
>Modest
68%b
>Modest
Time of Weaning
Early vs. Normal Weaning
0
10
20
30
40
50
60
70
80
90
100
NW EW
%
≥Choice- ≥Upper ChoiceWiseman et al. 2019. JAS 97:1198-1211
EW = 130 dNW = 226 d98 d dry lot period220 d grazing periodFeedlot finishing
Metabolic Imprinting – Early Weaned Steers
Scheffler et al. (2014)
Early weaned @ 105 d of age (MIP)Normal weaned @ 253 d of age (NW)
MIP fed CONC d 105 to 253NW and MIP were grouped and grazed for 156 dNW and MIP were fed corn-silage based feedlot diet to 0.4 – 0.5 in of backfat
645
518
0
100
200
300
400
500
600
700
MIP NW
Mar
blin
g sc
ore
, 50
0=
smal
l
Diet or Animal Age?
• Is it exposure to high concentrate diets OR early weaning?
Changes in IMF across Time-on-Feed (TOF)
0
2
4
6
8
10
12
0 28 56 84 112 140 168 196
%
Time-on-feed, d
TG PhL
Duckett et al., 1993, JAS 71:2079
Timing of Exposure to Concentrates (CONC)
Koch et al. 2018. Meat & Muscle Biol. 2:1-14.
CONC (n = 20)
FOR (n = 20)
FOR
FOR
FOR
FOR
CONC
CONC
Phase 1: 0-111d Phase 2: 97 d Phase 3: to 1250 lb
NW and 30d background
CONC: FOR:25% corn silage Novel fescue75% corn/sbm Annual ryegrass
AlfalfaCowpea
CONC-CONC
CONC-FOR
FOR-CONC
FOR-FOR
Study 1: Percent Choice or CAB
0
10
20
30
40
50
60
70
80
90
FOR-FOR FOR-CONC CONC-FOR CONC-CONC
% ≥Choice-
>CAB
a
a
b
c
a
bb
Study 2: Early Exposure
0
10
20
30
40
50
60
70
80
90
CONC FOR
%
≥Choice
≥CAB
Koch et al. 2019. Meat & Muscle Biol. (in revision)
Angus steers (n = 20)NW30-d backgroundFed for 111 d
Study 3: Time on CONC
0
20
40
60
80
100
0 40 80 120
%
Choice CAB
Insulin Resistance
Type II Diabetes
The proposed hypothesis for limited adipose tissue expandability. When the body is in a positive energy balance, the adipose tissue will expand to handle the excess energy. If the adipose tissue is not capable of expanding sufficiently, there will be a spillover of FFA to non-adipose tissue leading to harmful effects in liver, muscle and pancreas.
European Journal of Endocrinology 176, 2; 10.1530/EJE-16-0488
Conclusions
• Rethink our approach for calves with high marbling potential
• Marbling does not have to be a ‘LATE’ developingdepot
• Feeding high concentrates early is important• Creep feeding may help• EW vs NW
• exposure to concentrates early
• Early deposition will persist during forage finishing
• More research needs to be done…………
