By: Angus McColl
Integrity of Sampling and Use of Micron Results
The integrity of sampling, the careful and proper selection of a sample, is the most critical factor involved in measurement of fiber diameter in individual animals. The samples must be taken at the middle of the side in the blanket location. The sample should be uniformly cut at the skin level, which is the base of the staple, and should be no smaller than a two-inch square in size. The sample should be kept in the staple configuration, which is its natural growth state. It should not be brushed out, cleaned up, or folded. Flat bladed shears or clippers are recommended as the safest tools to use in the taking of samples.
Length of Fiber Sample
Maintaining the staple formation of the sample submitted to the laboratory is important for a practical reason: The two-millimeter sample used for measurement in the Laserscan is cut close to the base of the staple to measure fiber that has grown side by side under the same environmental conditions.
These conditions include level of nutrition, pregnancy, lactation, and stress caused by sickness or trauma. Recently shorn animals with shorter staple lengths generally have not been exposed to highly variable environmental conditions, so the variability of their fiber diameter may be limited. Working with staple lengths shorter than one and a half inches is problematic because the staple configuration breaks down and we are unable to take an even cut across the base during sample preparation.
Once the two-inch square sample is taken, it should be placed in a plastic sandwich-sized bag, and clearly labeled with the following identification:
I.D. Numbers (Eartag, Microchip, and/or Registration)
Age (Date of Birth Preferable to “2 Years”)
Sex (Male, Female, Gelding/Ram, Ewe, Wether/Buck, Doe)
Breed or Phenotype
Date of Sampling (Identifies age of animal’s fiber sample)
Major Factors Influencing Fiber Diameter
Three factors have a primary impact on fiber diameter: age, sex, and level of nutrition. As the animal matures, the fiber tends to have a higher or coarser micron value. Males frequently possess a higher micron value than females. The level of nutrition affects fiber diameter results as overfed animals produce higher micron values than those on a maintenance diet. This does not mean that animals should be underfed to produce finer fiber. Underfeeding causes significant negative side effects, such as lowered fertility, smaller birth weights, and higher infant mortality rates.
Fiber animals should be maintained on a thrifty diet to produce animals that live up to their genetic fiber potential. The safest guidelines to follow are those which follow animal husbandry practices suitable for your farm’s location and the advice of a veterinarian familiar with your stock. An unsound or unhealthy animal is a poor risk in a breeding program regardless of its fiber diameter results.
Genetics and selection are fundamental to producing sound animals with fine fiber. The fiber samples for individual animals included in our Laserscan database since June of 1994 appear to represent a broad genetic base in the U.S. A diverse genetic base creates opportunities for selection of desirable traits, including fiber fineness. A word of caution in animal selection, focusing on one trait increases the risk of negative traits which might be linked to the one being selected. Selecting for fiber fineness decreases the body size and fleece weights.
Understanding Laserscan Micron Test Results
The micron test report includes administrative information provided by the identification sent in with the individual sample. Depending on the height of the results, the histogram will be printed on a 12%, 24%, or 36% scale to fit our letter size report format. The bottom line (or horizontal scale) is measured either in one or two micron increments, with one micron equivalent to one thousandth of a millimeter or 1/25,400 of an inch.
To analyze the micron test report histogram, find the Average Fiber Diameter (AFD) on the horizontal scale showing fiber diameter in microns. Standard Deviation is a term representing an average of individual deviations (plus or minus micron values) from the mean or AFD. The smaller the Standard Deviation, the more uniform the population of fibers measured. It is the most stable of variability measures and is used in the computation of other fiber statistics such as the Coefficient of Variation (CV).
The Coefficient of Variation is the Standard Deviation divided by the Average Fiber Diameter multipled by 100 and reported as a percentage. The CV is used in the statistical analysis of different populations of fiber (different animals).
The percentage of fiber greater than 30 microns is also included in the report. In commercial application and breed selection, this data is of interest because it shows the coarse edge that determines the final use of the fiber. It has a relationship to the strength of the yarn processed from the raw fiber and influences “prickle” factor, the scratchy quality associated with coarser fibers.
The sample date is added to the report to identify the age of the animal at the time the sample was taken. A test report without a sample date is not as helpful as one confirming that the test results represent fiber taken when the animal was a specific age. The date of birth alone is insufficient to state that fact.
Equipment Used for Fiber Diameter Measurement
Yocom-McColl Testing Laboratory is equipped with the latest instrumentation technology for measuring average fiber diameter of animal fibers: Sirolan Laserscan, developed by CSIRO, and Optical Fibre Diameter Analyser, developed by BSC Electronics. Both companies are located in Australia. These instruments are calibrated using Interwoollabs tops, the only recognized supplier of calibration tops to the worldwide textile industry. A diagnostic and calibration check is performed each day on both instruments. The accuracy of measurement is plus or minus 0.3 microns and the tests are performed under standard conditions of 65% plus or minus 2% relative humidity (RH) and a temperature of 70 degrees plus or minus 2 degrees F.
A Marketing and Genetic Selection Tool
When utilized properly, objective fiber testing can be a powerful marketing and genetic selection tool. Objective measurement is an assessment made without the influence of personal feelings or prejudice. Visual appraisal and fiber handling are fundamental aspects of fiber judging, but very weak appraisal methods of accurately identifying fiber diameter.
Instrumentation can accomplish the measurement of fibers within a micron. Because the measurements are so tiny, the difference between a sample at 20.5 microns and one at 22.5 microns is small mathematically, but critical in commercial use and pricing structure.
Based on this factor alone, fiber-testing technology gives breeders a useful tool to analyze fiber and track the progress of their selection programs. The determination of average fiber diameter helps identify the best end use for fiber and is information that mills require before making their purchasing decisions.
The ability to provide information on fiber quality places natural animal fiber producers in a stronger position to receive what their fiber is worth. Very few people buy and sell commodities without knowing everything they can about them. Information is power in the marketing world, and objective fiber assessment provides it.
The micron test is as good as the sample and the information submitted for testing. The laboratory cannot jeopardize its integrity by providing results from improperly taken samples, either by location or size. Breeders have the same interest in maintaining their reputations with high quality animals and by keeping accurate records of their overall performance.
Yocom-McColl Testing Laboratories, Inc. was formed in 1963 by Angus McColl and Ira Yocom (retired). The company started operations as an independent wool and animal fiber testing laboratory in January, 1964. The lab utilizes ASTM (American Society for Testing and Materials) and IWTO (International Wool Textile Organization) procedures and methods when testing fibers.
Angus McColl graduated from the University of Wyoming with a Bachelor’s degree in Animal Science and a minor in Agricultural Economics. He was a graduate assistant in Wool Technology when he took a post as Wool Specialist for United States Testing Company, located in Denver, Colorado. He left US Testing to form his own company and since has been actively involved in developing equipment for sampling, subsampling and scouring wool in a commercial testing laboratory environment. McColl is a native of Scotland.
McColl has promoted correlation testing in the textile industry and runs ongoing correlations with most quality control labs in domestic commercial mills and university wool science departments. He is currently a member of the ASTM D13.13 wool committee and is a representative for objective measurement in the American Sheep Industry Wool Council’s Fiber Group. He actively supports activities within state wool grower associations in Colorado, Montana, South Dakota and Wyoming. McColl is the U.S. representative at the annual technical meeting of the International Wool Testing Organization in Nice, France. In 1995, McColl was added as a technical advisor to the Alpaca Registry Screening Committee (ARSC) in the fiber standards area.