Evaluating Fat and Muscle in Livestock Developed by: Celina Johnson University of Florida.

Evaluating Fat and Muscle in Livestock

Developed by:Celina Johnson

University of Florida

Why is it Important to Evaluate Fat and Muscle?

• Meat Animals - we sell muscle• All gender classes - important

– Intact males, market animals and replacement females.

Johnson, 1997

How Do Animals Get Fat?

• Top to Bottom• Front to Rear

Johnson, 1997

Growth Curve

Time

Wt.1

2

3 4

1. Prenatal2. Rapid Growth3. Fat deposit begins4. Fat

puberty

market

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Effects of Sex

Female usually deposits fat earlier than castrates or intact males.

Cattle: Heifers market at lighter wts.

Exception: Swine

boar gilt barrow

lean fatJohnson, 1997

Effects of Frame Size

Small Framed animals:

Greater deposit of fat at lighter weights

At the same body composition, small animals will be lighter.

Johnson, 1997

At Equal Body Composition:

Weights: Lg > Med > SmallEfficiency: Equal, same point on

growth curve

At Equal Weight:

Efficiency: Lg > Med > Smallwhy? Composition

Johnson, 1997

Effects of Frame SizeEffects of Frame SizeAge InfluencesAge Influences

Wei

gh

t

Age

Large

Medium

Small

Johnson, 1997

Wei

gh

t

Age

Effects of Frame SizeEffects of Frame SizeWeight InfluencesWeight Influences

Large

Medium

Small

Johnson, 1997

Fat Deposition Sites

• Brisket (cattle), Jowl (hogs), Breast (lambs)

• Ribs • Loin Edge • Twist Area • Flank• Tailhead area

Johnson, 1997

Fat Deposition Sites

Johnson, 1997

Muscle Evaluation Sites

• Hindquarter (round - cattle; leg - lamb; ham - hog)

• Stifle • Forearm• Over Top - loin and rump• Width of Base

Johnson, 1997

Muscle Evaluation Sites

Johnson, 1997

Muscle Evaluation Sites

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Body Shapes

Desirable Undesirable

The widest part of the animal should be at the stifle, indicating lean, not

fat

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Lean Hog

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Over Finished Hog

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Under Finished Beef

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Over Finished Beef

Johnson, 1997