AFD

Average Fiber Diameter (microns).  This number reports how wide in cross section, the individual fibers in a fiber sample are on an average.   To determine this number, a 2 inch square fiber sample is clipped from the side of the alpaca's blanket as close to the skin as possible.  The sample is then sent in to a testing lab such as Yocom-McColl Testing Laboratories where they take the fibers in the sample and cut a 2-millimeter sample from the base of the sample (the part which was closest to the skin).  A laser then scans through the fiber sub-sample and measures the diameter of several thousand individual fibers.  The individual fiber diameters are then averaged to obtain the AFD.

A typical alpaca at about 1 year of age has an AFD of about 25 microns.  A micron is a unit of length equal to 1/1,000th of a millimeter or 1/25,400th’s of an inch.  As an example of how small a micron is, consider the following ...

Take a piece of paper and a ruler. Mark and cut off a 1 inch wide strip of any length from the original piece of paper. Now cut the 1 inch wide strip in half to obtain a strip 1/2 inches wide. Cut the half in halves for a 1/4 inch wide strip. Now cut the half in halves again (1/8 inch). Now carefully cut the strip into 3,175 equal pieces. You've now got a strip (actually a whole bunch of strips) which are 1 micron wide.

SD

Standard Deviation (microns). The more variation within the fleece the higher this number will be. If a fleece has lots of thick fibers mixed in with the thin fibers then the standard deviation will be high. You want this number to be such that the CV (see below) is less than 24 to 25.  Many breeders and fiber experts do not talk much about the SD. They instead refer to the CV to express, in one way, how consistent the fleece is. (top)

CV

Coefficient of Variation (percent).  This is the SD (Standard deviation) divided by the AFD (Average Fiber Diameter).  Lets say we have an alpaca with a AFD of 20. If the SD for this alpaca is 4 then 4/20 = CV = 20%, a very good number.  CV is the one of the keys to use to evaluate the variation in the fleece.  The lower the CV, the more consistent (the more alike) the fibers are within the fleece sample.  An excellent number for CV is 20 or below.  The average is around 24 to 25.  A high number such as 30 would mean a pretty poor quality fleece, even if the AFD was low!

Lets say we had a 25 micron fleece (AFD), which is about normal for an alpaca, but the CV is unusually high at 30.  Although the average is acceptable, the deviation is way too high.  This would be like reporting a person's body temperature as being normal, but, the person's head is in the freezer and the feet are in a hot oven.  With the head at zero degrees and the feet at 200 degrees, the person's average temperature would indeed be about normal, but the deviation (the variation) would be ridiculous!

CV is also important in that it allows the consistency of one alpaca to be compared to another.  If we have one alpaca with an AFD of 20 and a CV of 21, and another alpaca with an AFD of 17 and a CV also of 21, then we can say although one alpaca is finer than the the other, both have equal consistency.  (top)

%>30

Fibers Greater than 30 Microns (percent), or the Prickle Factor.  Garments having contact against more sensitive skin (such as a scarf, sweater, skirt, or suit) must be made of finer fleece or the clothing will cause prickle or itch to the wearer.  Comfort tests have suggested that high quality garments of these types should be made of fleece which has a Prickle Factor of less than 5%.  When a fleece analysis is run, the report will show what percentage of the fiber is greater than 30 microns.  A high quality fleece will have this number at 5 percent or less. 

As the alpacas ages, the prickle factor will continue to become greater as the alpaca's fleece become more coarse.  It is truly a remarkable alpaca which maintains this number below 5% when it is more than 3 to 5 years of age. (top)

Histogram

A fiber analysis report (one is pictured to the right) showing both a numerical and a graphical representation of the AFD, SD, CV, and %>30 for a given fiber sample.  (top)

ARI Recognized Fiber Colors

The following table of colors is used by the Alpaca Registry Incorporated (ARI) to color classify an alpaca.  Since there are hundreds of variations of natural colors in the alpaca, the color spectrum must be simplified for ease of coding and entering alpacas into the national registration database.  The ARI recognized colors are represented by the following 16 color swatches.  If an alpaca is between shades (darker than one shade, say light fawn) but lighter than another (medium fawn) then the alpaca is to be coded to the darker shade (medium fawn). 

Alpacas are primarily shown in these color groups and are shown in the order of dark to light.  Blacks will enter the ring first to begin an alpaca show.  They will then be followed by the browns, fawns, and whites.  A show will finish with the fancy colors such as the greys and the multiple colors (the multi's).  If you like to go home early then stick with the blacks ;-)