Live Market Hog Evaluationand Grading

Developed by:B. A. Reiling, Ph.D.

University of Nebraska-Lincoln

Visual Evaluation• Subjective• Less accurate than real-time ultrasound• Less expensive, more convenient• Still important for selection decisions• Still important for marketing decisions

Value-determining Traits• Weight

– Live weight (LW)– Carcass weight (HCW)

• Dressing Percent (DP)– Relates LW to HCW– HCW = LW X DP

• Leanness– 10th rib fat thickness– Last rib fat thickness

• Muscle– Loin muscle area– USDA muscle score

Average Values• Live Weight

– Range: 230 – 300 lbs

– Average: 272 lbs• Dressing Percentage

– Range: 68 – 78%– Average: 75%– Affecting factors

• Fill, muscle, fat

• Carcass Weight– = LW * DP– ~ 200 lbs

• Length– First rib to aitch bone– Shoulder point to ham– Range: 28-34 in– Avg: 31 in ()

How Do Animals Get Fat?

• Top to Bottom• Front to Rear• Gender Effects

– Gilts leaner than barrows

Body Shapes – Rear View• Heavy muscled hogs are wide based

Desirable Undesirable

Body Shapes – Top View• Lean hogs = “hourglass shape”• Fat hogs = “boat shape”

Desirable Undesirable

Evaluation of Fat Deposition

16 4

23

1) Jowl2) Blades3) Forerib

4) Elbow pocket5) Loin edge6) Flank

7) Tail head8) Ham seam

5 5

8

7

Average Values• Last rib fat thickness

– Used for calculation of lean content in the industry• 10th rib fat thickness

– ¾ length of the eye muscle; corresponds with “loin edge”– Used to calculate % muscle– Range: 0.35 – 1.2 in ()– Avg: .7 in – But, carcasses are NOT ribbed

Last Rib vs. 10th Rib Backfat

Last rib BF, in. 10th rib BF, in. .60 .45 .80 .80 1.00 1.20 1.20 1.55 1.40 1.95

Lean Hog

Fat Hog

How Lean? How Fat?Wt = 247 lbs Wt = 252 lbs

How Lean? How Fat?LRF, in 0.6010th rib fat, in 0.30LEA, sq in 9.50% Lean 63.16

LRF, in 1.0010th rib fat, in 1.60LEA, sq in 4.50% Lean 39.82

Evaluation of Muscle

1

2

3

1) Shoulder2) Forearm

3) Loin (top)4) Ham/stifle

4 Thick Ended

Average Values• Loin Eye Area (LEA)

– Loin Muscle Area (LMA)– Longissimus dorsi– Ultrasound measure– Range: 4.5 – 10.0 in2

– Avg: ~ 6.0 in2 ()

USDA Carcass GradingTwo Factors:• Last rib backfat (LRBF)• Muscle Score (MS)

– Thick = 3– Average = 2– Thin = 1

• = (4 * LRBF) – MS– Thin muscled hogs

ineligible for USDA #1

USDA Muscle Scores

Thin = 1 Average = 2 Thick = 3

Cutability Values• Various equations to predict % muscle (lean)

– May include 0 (fat-free), 5 (marbling), or 10% fat• Observations

– As live weight , % muscle – As fat cover , % muscle – As LEA , % muscle

Critical Factors = Fat Cover and Weight

Percentage Fat-Free Lean

• Short-cut Method– 250 lb live weight = base

• For every 10 lbs below; add 0.2%• For every 10 lbs above; subtr 0.2%

– 0.8 inches 10th rib fat = base• For every 0.1 in below; add 1%• For every 0.1 in above; subtr 1%

– 5.5 in2 LMA = base• For every 0.1 in above; add 0.2%• For every 0.1 in below; subtr 0.2%

• Typical range: 48-60%– Extremely lean pigs >60%

• With heavy-weight hogs– Frame very important

Convert percentage lean pounds of fat-free lean

live weight X 100

• Can use ultrasound • Pounds of fat-free lean:

.833 * Sex (barrow = 1, gilt = 2)+ .291 * live weight, lbs- 16.498 * 10th rib fat, in+ 5.425 * LMA, in2

- .534

Practice 1

Dress %Hot Carcass WtLRBF10th Rib FatLEAMuscle ScoreUSDA Grade% Lean

77.6%187 lbs0.60 in0.50 in8.0 in2

20.458.1%Live Weight = 241 lbs

Practice 2

Dress %Hot Carcass WtLRBF10th Rib FatLEAMuscle ScoreUSDA Grade% LeanLive Weight = 274 lbs

77.9%214 lbs1.00 in1.05 in7.4 in2

22.050.2%

Practice 3

Dress %Hot Carcass WtLRBF10th Rib FatLEAMuscle ScoreUSDA Grade% Lean

73.0%186 lbs0.70 in1.00 in5.9 in2

20.848.9%Live Weight = 254 lbs

Let’s Look at Some Live Pigs!