Understanding Ultrasound
The first thing producers want to know about ultrasound is, How
accurate is it? The answer to this question depends on who does the actual scanning
of the animals and who interprets the images. Ultrasound data should be collected
and analyzed by a technician that is certified by many breed associations. Every
year technicians are re-tested to see if the data they submit will be accepted
by the breed associations for EPD calculations. Each year, all technicians go
to a centralized location to scan the same 20 head of cattle twice, in random
order. The next day the cattle are harvested and the actual carcass results
are collected. These actual results are compared with each technician's ultrasound
results. The technicians are tested to see how close their data compares to
the actual results and how close the repeatability is for each animal. The results
are sent to a committee made up of statistical scientists to analyze each technician's
results to see if the technician meets predetermined standards. The accuracy,
although not perfect, is high enough that bulls selected (based on ultrasound
data) results in positive genetic change in progeny carcass traits. Heritability
for carcass traits are moderate to high, which is slightly higher than heritability
for birth weights, weaning weights, and yearling weights.