Body Composition Flashcards
Why measure body composition ?
Animal health
How much is edible
How efficient an animal is
How much an animal produces
How much money it will bring you
How effective your management systems are
The sequence of tissue depot development from earliest to latest is…
Skeleton → muscle → fat
How to measure body composition
Live weight measurement
Dissection
Body measurements
Visual assessment: body condition score
Dilution techniques
Dual energy X-ray absorptionmetry (dexa)
Computerized tomography (CT)
Magnetic resonance imaging (MRI)
Ultrasound
Bioelectric impedance
Carcass video image analysis
Carcass probes
Dilution techniques
Tracers
Measures total body water
Indirectly measures body fat → inverse relationship with water
Tracers are difficult to apply
Standardization required for meaningful results-total body water, bladder, GIT
Dual energy X-ray absorptiometry (DEXA)
Measures absorption of rate of ionizing radiation
Originally developed to determine bone density /bone mineral composition inx humans
Can predict chemical composition in live animals, carcass or meat
Cheaper, faster, and easier than CT and MRI
Computerized tomography (CT)
Computer assisted tomography (CAT)
Like DEXA, differentiates tissues based on their density
Expensive
Time required to obtain estimate is high
Require to anesthetize the animal before scanning
Magnetic resonance imaging (MRI)
MRI is based on the magnetic resonant (vibration) properties of protons associated with water and lipid molecules of tissues
It examines proton distribution and binding in the body
Defects differences in tissue by among of protons
Strongest vibration from fluid and lipid, intermediate from muscle and tendon, weakest from teeth and cortical bone
Advantages → non-invasive, No radiation, highly discriminating of chemical elements
Ultrasound
Transducer is the heart of the ultrasound system
When electrical signals is applied, the transducer produce high frequency sound pressure wares
Reflected or “echoed “ pules are converted to electric signals and computer converts them into points and measured
Bioelectric impedance
Differential resistance to electrical current by tissues
Drop in voltage from one electrode to another is measured
Send an electrical signal through the animal carcass and defect how much impedance or resistance to that flow of electricity
The carcass gives the more resistance
The more animal the more fat
The less resistance or impedance the carcass the less fat they have
Resistance is inversely related to body water content (same as addpose to water)
Carcass video image analysis
Cameras and computers
Measures grade fat, rib eye width and length and then calculates a lean-yeild percentage, providing a lean-yeild grade and a marbling score
Carcass probes
Subcutaneous fat depth → ruler
All probes measure thickness as well as back fat thickness
FOM>HGP> ruler for measuring subcutaneous fat depth and predicting carcass lean
