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LM-12 Inst Man Short Form-AB.doc 12/24/06
For swine, only site B (see the drawing below), will give an accurate reading of the 3 layers of
fat. Many hogs have a third layer of fat. As they increase in weight and age, the third layer
becomes thicker and more widespread over the body. Site B is the location normally used in the
old metal ruler probing technique, and shows the best correlation with overall carcass yield.
Because of the trapezius muscle at the shoulder (false lean), measurement at site C is more
difficult and inconsistent. (True for both ruler and ultrasound devices). Site A will give accurate
measurement for two layers of fat but may not give an accurate measurement for three layers of
fat due to the muscle tissue below the fat layers.
Values obtained using ultrasonic devices on live animals will generally be different than those
measured at slaughter because of differences in measurement sites and fat on a hanging carcass
is distorted or cut.
Example: Locating The Test Site For Swine
The most accurate spot in which to measure backfat can be found by walking your fingers
forward along the hog’s flank until you can feel the last rib, then place the probe on this site B,
65mm (2.5 inches) from either side of the backbone. Saturate the skin with a light oil (such as
cooking oil) or water.
Important:
Small irregularities in the fat may block the beam of sound,. Moving the probe
slightly will allow the beam to bypass, and the correct reading to appear. Fat layers are not
uniformly thick. Averaging two or three readings at adjacent sites insures greatest accuracy.
Measurement occurs only when the Read lights are on. Older animals with tough dead skin will
require extra effort to obtain a good clean probe contact with the underlying live tissue. If
necessary, remove the hair at the site (true for all mammals). Then wet the skin with hot water.
Next, apply light oil and allow it to wet the skin a minute or two before measuring.
Charging the Battery and Low Power Indication
Plug the RENCO charger into a wall outlet that supplies the rated charger voltage and plug the
charger cable into the instrument.
NOTE: Charger light stays lit until charger is
disconnected.
Charge the battery for about 15 hours before the first use. (Charging the battery
after each period of use for three times longer than the time it was used insures long battery life.
Do not make a practice of charging the