Susan K. Duckett Clemson University

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…………