The Case of the Missing Coarse Fibres

Explaining the ‘Trim High’ setting on OFDA2000 fibre testing equipment.
By Paul Vallely, AAFT Fibre Testing Laboratories, in consultation with Mr Mark Brims (BSC Electronics), inventor/manufacturer of OFDA technology

When I first became involved with fibre testing alpacas over 15 years ago, about the only figure on alpaca fibre test reports that received any interest was the average fibre diameter (microns). Thankfully, SD is now co-starring alongside micron, as breeders appreciate the need to reduce fibre variability when breeding towards quality fleeces.

Most alpaca fibre testing these days is carried out using OFDA2000 fibre testing equipment. OFDA2000 equipment measures the full length of the fibre sample. It can measure fibre samples after the samples are ‘scoured’ or cleaned of lanolin, seeds, grass etc, or it can be used to test raw fibre samples using capabilities to offset the presence of impurities on the fibres. Another form of OFDA testing technology used when testing alpacas is the OFDA100, although these devices are no longer manufactured. Lazerscan is another form of testing technology, but is not as widely used when testing alpacas.

This paper refers only to the use of OFDA2000 testing devices.

Accuracy and Precision

Paul Vallely testing fibre

When breeders use fibre test results, there are two elements that underpin their ability to rely on the data. Firstly, the results need to possess a high degree of accuracy, whereby the test results give a true account of what has just been measured.

Secondly, the test needs to possess a reasonable degree of precision, that is, the test result needs to be relatively repeatable. Put another way, if we test one midside sample from one alpaca, then test more midside samples from the same alpaca, yet the results continually have significant differences, then any of these test results would be useless. There would be no way of telling which result can be relied upon.

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