Well, I'm not going to try to fight a battle with those who prefer the OFDA 2000. However, that testing protocol is not recognized by the IWTO, and those results are not able to be included in the EPD database.
I had a fleece with tender breaks a couple of years ago. I can tell at what time of year it occurred, and I can guess as to the reason, just as easily as if I'm looking at a graph telling me my fleece is tender. If a fleece has tender breaks in many places along the length of the staple, again, you can guess at the reasons from your own observations as easily as looking at a graph. And if a fleece is tender, it is not useful at all in commercial processing, so a processor is not going to want it whether it's 17µ or 22.5µ, especially the sample in question which was only 2.5" to begin with.
That anomalous tender spot that is averaged in to give you a false low AFD is actually a disservice to those who may want to make use of a sire who tested 17µ at 2 years, rather than the truthful 22.5µ at 2 years.
Heather
On Oct 24, 2009, at 9:02 AM, Rebecca Wells wrote:
Heather Zeleny wrote:
For example:
I know of an animal with a first year AFD very similar to one of my
boy's first year AFD, 16.6 as tested by Yocom McColl.
The second year, the owner tested on the OFDA 2000. The staple length
was 75mm, just about 2.5" The AFD came back at 17.4µ. However,
according to the OFDA 2000, the beginning micron was a bit over 18 at
the weathered end. Between 5 and 15mm, the micron drops to about 16µ,
then steadily rises over the course of the growth period to 22.5 at
70mm.
This sample, tested at Yocom McColl would have been recorded as 22.5µ
This sample has a 6µ variance. In fact, this shows that the fiber is
tender at 15mm, perhaps there was stress of illness which made the
micron so low during that time. But surely this fleece isn't a
uniform 17.4µ
Finally, it seems that really, the accurate micron of this boy at two
years of age is 22.5µ. Because that was his micron at that age.
So what would happen if the fiber sample had been sent to Yocom McColl at the timeframe when the fleece was at 15mm? Or more realistically, whatever was affecting the animal at the 15mm point, happened to coincide with the 2yr shearing time? Do you see how that would also skew the results just as surely? However, by taking the true average of the fiber diameter over the course of a year, the AFD is a "more average average", if you get my point. If in fact this animals fleece is coarsening due to age, the subsequent tests will reflect that with increased AFD results. However, the breeder can look at that information and check to see if the increased micron count from 15mm to 70mm with some environmental changes, such as a change in diet. Then, if so, that can be factored in and perhaps changes can be made to correct whatever environmental factors might be contributing to the increased fiber strength. However, if no changes happened in the animals environment that might explain the changes, it might be genetic.
But one thing for sure, you don't get that kind of useful information from a Yocom McColl test.
Rebecca Wells
Alpacadero Alpacas
Seattle, WA
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