Carcass Apprasial, Grading & Evaluation

Includes slides from the lab

How is grading sorted?

Within sex classes

• Classified by gender and maturity based on relative values

What is an animal grade?

Predicts the carcass an animal will produce, based on evaluating the live animal (before slaughter).

What is a carcass grade?

Groups carcasses of similar market desirability, based on relative palatability (quality grade) and/or cutability (yield grade) — evaluated after slaughter.

What does it mean that livestock are heterogenous?

Individual animals vary in sex, maturity/age, fatness, and muscling — grading exists to sort this variation into uniform, predictable groups.

What is the purpose of grading?

To sort a heterogeneous population into homogeneous groups of similar value/desirability.

How do sexes differ?

Differences result from age of marketing vs age of puberty.

• Dressing percentage

  • Males are higher

• Carcass proportions

  • Female normally smaller

• Cutability

  • Yield grade (% of muscle coming off of skeleton)

• Palatability

• Acceptability

As an animal increases in age, what happens?

They become:

• Less tender

  • Collagen increase

• More flavorful

• Darker in lean color

• Yellow in fat color

• Diseased

• Fatter

What causes a yellow fat color? How can it be reversed?

Forage-based diets

• Can be reversed by feeding a grain diet for the last few months of life

What are the beef maturity classes?

A, B, C, D, E

• A is youngest, E is oldest

Pubery vs age of marketing for beef

• Puberty: 12 months

• Market: 18 months

Pubery vs age of marketing for swine

• Puberty: 7 months

• Market: 7 months

Pubery vs age of marketing for sheep

• Puberty: 8 months

• Market:

  • 8 months — “spring lambs/lamb”

  • 14 or older — “old crop/mutton”

What do quality grades predict?

Palatability (eating experience: tenderness, juiciness, flavor).

What do yield grades predict?

Cutability — the % of the carcass that becomes salable muscle (boneless, closely-trimmed retail cuts) rather than fat, bone, or waste.

What are the two systems for palatability estimation?

• Dichotomous (bipartite): binary pass/fail — acceptable or unacceptable. Used for pork.

• Hierarchical: a ranked scale (poor → best). Used for beef and lamb.

What palatability estimation is used for each species?

• Pork: Dichotomous

• Beef: Hierarchy

• Lamb: Hierarchy

How are cutability grades defined?

An estimate of the proportion of lean, edible meat a carcass will yield from its major wholesale primal cuts, relative to bone and fat.

How cutability is measured differently by species

• Pork: bone-in, skin-on, closely-trimmed primal cuts

• Beef & Lamb: boneless, closely-trimmed retail cuts from the primals

What does a yield grade of 1 mean? A yield grade of 4-5?

• YG 1 = highest cutability (most usable lean meat per carcass)

• YG 4–5 = lowest cutability (fattest, most wasteful carcass)
  (Applies across beef, lamb, pork — though pork only goes to US #4, not 5.)

What happens as an animal increases in weight?

Its carcass becomes fatter and, therefore, its retail cuts become larger

What is the purpose of the USDA meat grading service?

Apply quality and yield grades

• Both grading and inspection are USDA programs

Who administers meat inspection?

USDA’s Food Safety Inspection System/Service (FSIS)

What is the difference between inspection and grading?

Inspection

• Required by law

• Funded through tax dollars

Grading

• Not required by law

• Purchased from the US government by meat packers and processors

All animals and their carcasses must pass what before they can be graded?

Inspection

what shape are USDA AMS carcass stamps?

Shield-like

Ovine Sex Classes

• Ewe

  • Female

• Wether

  • Male that was castrated before reaching puberty

• Ram

  • Uncastrated male

• Stag

  • Male that was castrated after reaching puberty

Lamb Quality Grades

• Prime

• Choice

• Good

• Utility

• Cull

  • Utility and Cull tend to be very old sheep

Lamb Yield Grades

• 1, 2, 3, 4, 5

  • 1 is greatest cutability, 5 is lowest

Lamb Yield Grade Factors

• Back fat

• Body wall

• Loineye area

• Hot Carcass Weight

Measuring Loineye Area and Body Wall Thickness on Lamb

Factors that determine lamb quality grade

• Leg conformation score

• Flank streakings

• Carcass maturity

  • Break vs Spool joints

  • Flank color

Break and Spool Joint

Spool = older

• Think “spool of yarn,” as older folk tend to knit

Porcine Sex Classes

• Gilt

  • Female that has not given birth before

• Barrow

  • Male that was castrated before reaching puberty

• Sow

  • Female that has given birth before

• Boar

  • Uncastrated male

• Stag

  • Male that was castrated after reaching puberty

Porcine Muscling Scores

• Thick = 3

• Average = 2

• Thin = 1

Porcine muscling scores are based on (live weight/carcass/both) basis

Carcass

Porcine Yield Grades

• US #1, 2, 3, 4

  • 1 is greatest cutability, 4 is lowest

Bovine Sex Classes

• Heifer

  • Female that has not given birth before

• Steer/Bullock

  • Castrated male

• Cow

  • Female that has given birth before

• Bull

  • Uncastrated male

How is beef quality evaluated?

• Skeletal maturity

• Lean maturity

• Degree and distribution of marbling

Bovine Maturity Groups

A, B, C, D, E

• A is youngest, E is oldest

How is the maturity group for a bovine determined?

• Dentition; teeth

• Ossification of the cartliaginous buttons

• Ribs

  • Older animals: whiter, wider, flatter

  • Younger animals: red, round, porous

What is the maturity cut-off for bovines? What do we risk with cattle older than the cut-off?

30 months

• Older than 30 months increases risk of BSE

For maturity group determination of bovine, how is dentition used to determine age?

Based on the eruption of the incisors

• Figure 6 shows full eruption and leveling

• Figure 3 shows rough cut-off point (~30 months)

Bovine Yield Grades

• 1, 2, 3, 4, 5

  • 1 is greatest cutability, 5 is lowest

How are bovine yield grades determined?

4 considered factors:

• Preliminary Yield Grade (PYG)

• Ribeye Area (REA)

• Hot Carcass Weight (HCW)

• % of Kidney, Pelvic, and Heart Fat (KPH)

Bovine Quality grades

1. Prime

2. Choice

3. Select

4. Standard

5. Commercial

6. Utility

7. Cutter

8. Canner

How are bovine quality grades determined?

1. Marbling score (Abundant → Practically Devoid)

2. Carcass maturity (A → E)

Dressing percentage

Weight of the hot carcass expressed as a percentage of live weight

• Must know formula

What two basis can an animal be sold on?

1. Live Weight

2. Carcass

What does selling on a live weight involve?

The slaughter weight of the animal and its live price on a per hundred weight ( 1 cwt = 100 lbs) basis

• $0.66 / lb x 100 = $66/cwt

  • 1,200 lbs / 100 = 12 cwt

    • 12 cwt x $66/cwt = $792 total

Drift

Live weight shrinkage due to feces, urine, fasting, etc

What is the average % drift?

4%

Drop Credit

Potential revenue to be recieved for the byproducts of a live animal

• Hide and offal

Todays beef is typically sold on a combination of what?

Yield and quality grade

Hardbones

Defect seen in carcasses with C, D, and E maturity

• Also called “blue backs”

• Caused by age—increase of ossification

Dark Cutter

Defect resulting in darker-colored meat

• Caused by long-term stress

Heavy Carcasses

Defect seen by double-muscled cattle

• Caused by double-muscled gene (defective myostatin)

Conformation

Defect seen primarily in dairy cattle

• Caused by Holstein genetics

Calloused Eye

Defect seen in a carcass caused by Steatosis

• Caused by an injury long before harvest

Yellow Fat

Defect seem from a forage-based diet

• Caused by beta-keratin in plants

Hump Height

Defect seen in Bos Indicus (Brahman) cattle

• If the hump exceeds 2 inches in height, the meat cannot be sold as Angus beef

Blood Splash / Ecchymosis

Defect seen from hemmorages in the veins and artieries in the muscle

• Caused by stress just before death (bursting of capillaries)

What primal cuts are at each position of the beef carcass?

1. Chuck

2. Rib

3. Loin

4. Round

What primal cuts are at each position of the lamb carcass?

1. Shoulder

2. Rack

3. Loin

4. Leg

What primal cuts are at each position of the pork carcass?

1. Picnic Shoulder

2. Boston Butt

3. Loin

4. Ham