We
answer your questions about the OFDA2000.
Question: How accurate is the OFDA2000?
Answer:
Accuracy is the ability to obtain a result that is similar
to a reference method. In the case of the OFDA 2000, one
may regard accuracy as the closeness to an equivalent
result obtained by core tests using a certified method.
On average the calculated lot mean, based on OFDA 2000
measurements obtained on mid-side samples, should be within
0.5 µm of a core test measurement taken on the same
wools. |
|
 |
--------------------------------------------------------------------------------
Question: How precise is the OFDA2000
when compared to other wool testing measurement technology?
Answer:
Precision is an indicator of how repeatable a measurement
is. The precision of measurement of the mean fibre diameter
of a single mid-side or hip-bone sample from a single
animal, when conducted by OFDA2000, is as repeatable as
a typical mid-side test carried out by a fleece testing
laboratory (based on measurements being conducted under
standard conditions of use). On a single fleece, the published
precision is approximately +/-1.0 to 1.2µm, which
is similar to the precision of conventional (laboratory)
fleece testing. |
|
 |
-------------------------------------------------------------------------------
Question: The OFDA2000 measurement is
based on sub-samples drawn from a mid-side or hip-bone sample
site. Are both sample methods adequate and accurate?
Answer:
IWG recommends users should choose the mid-side as a sample
site when wool preparation is their primary reason for using
OFDA2000 or if the test results will be used in more complex
decision systems, such as Estimated Breeding Values. This
is because the mid-side of the sheep has a very high correlation
to the whole fleece.
When using the OFDA2000 ranking animals,
the hip-bone site is readily identifiable and repeatable,
which makes it the preferred option for many users. The hip-bone
site on a sheep is generally the strongest part of the fleece
and the user must take this into consideration.
--------------------------------------------------------------------------------
Question: Using OFDA2000, how many sheep
can be tested per day under normal farm conditions?
Answer:
With good yards and shed facilities, a comfortable day
is 800 and experienced operators are regularly achieving
1100 or more tests per day. |
|
 |
--------------------------------------------------------------------------------
Question: How can we practically incorporate
OFDA2000 technology into our genetic selection and wool harvesting
process?
Answer:
Most OFDA2000 users choose to test close to shearing, using
the technology as a tool to enhance the power of subjective
selection (visual sheep classing). IWG recommend using on-farm
wool test results in conjunction with greasy fleece weight
data and other objective and subjective breeding traits. Careful
consideration should be given to style grades when using subjective
traits for selecting animals to be retained in the flock or
preparing lines of wool.
|
