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 4 3 2 1 1. Prenatal 2. Rapid Growth 3. Fat deposit begins Time Wt. market 2 puberty 1. Prenatal 2. Rapid Growth 3. Fat deposit begins 4. Fat 1 Johnson, 1997

Female usually deposits fat earlier than castrates or intact males. 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 fat Johnson, 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 > Small Efficiency: Equal, same point on growth curve At Equal Weight: Efficiency: Lg > Med > Small why? Composition Johnson, 1997

Effects of Frame Size Age Influences Large Medium Weight Small Age Johnson, 1997

Effects of Frame Size Weight Influences Large Medium Weight Small Age 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 Johnson, 1997

Body Shapes The widest part of the animal should be at the stifle, indicating lean, not fat Desirable Undesirable Johnson, 1997

Lean Hog Johnson, 1997

Over Finished Hog Johnson, 1997

Under Finished Beef Johnson, 1997

Over Finished Beef Johnson, 1997