SCIENCE Surface Scanning Electron Microscopy of Suri Alpaca Fiber and Other Members of the Camel Family By Andy and Dr. Cheryl Tillman SEM scanning demonstrates that the To provide a baseline to other members cuticular cell length, height, and scale of the Camel Family, 19 llama, eight edge angle of suri alpaca fiber is huacaya, six vicuña, five guanaco, and measurably different from huacaya two de-haired Bactrian camel samples alpaca, cashmere, wool, and other were also analyzed. Other specialty members of the Camel Family. fibers analyzed included one sample The Washington State Disease Diag- each of white angora rabbit, washed nostic Lab (WADDL) in Pullman, WA fawn mohair, and Bombay silk. Two analyzed 35 suri alpaca fiber samples samples each of Soft Rolling Skin® with surface scanning electron micro- (SRS) merino wool, and both domestic scopy in February through November (in the grease) and very fine, washed 2005 for the authors. The WADDL white Chinese cashmere were tested. normally uses the Electron Microscopy SEM scanning demonstrates that the and Imaging Center (EMIC) to cuticular cell scale length, frequency, identify virus and bacteria species for height, and scale edge angle of suri the state of Washington. Samples were alpaca fiber is measurably different Suri fiber is characterized by an indistinct scale prepared by EM Supervisor Chris from these other specialty fibers and edge that is difficult to visualize even with Davitt, Ph.D., who took two micro- other members of the Camel Family. digital imaging tools. graphs of each fiber sample. Cuticular scale length is expressed as the Mean Scale Frequency (MSF) per Terminology 100 micron (µ) field of view as meas- ured by the SEM. High-luster suri appears to be most similar to cashmere, Angstrom (Å): A unit of length, equal to one ten-millionth of a millimeter, primarily used to express electromagnetic wavelengths. though it has an even longer and lower Compound Microscope: An optical microscope with two ocular lenses. scale height. This study has important Cuticular Cell Scale: The external-most structure of hair. implications for the alpaca industry, Highly Evolved: a merino or huacaya that has a high frequency of crimp, or including AOBA and the AFCNA. Suri a suri with unusually high luster or tightly-penciled locks. alpaca breeders can now claim to pro- Mean Scale Frequency (MSF): The number of cuticle scales per 100 micron duce a natural fiber which has luster that are the mean of the data set. that is equal to or greater than cashmere. Micrograph: A digital photograph of the SEM sample. Due to its very low cuticular scale Micron: 1/1,000,000 of a meter (1/10,000 of a millimeter, or about 1/25,000th of height, both suri and huacaya breeders an inch). can explain why their products have Scanning Electron Microscopy (SEM): Use of the electron microscope to view the surface characteristics of an object. superior handle, compared to wool of South American Camelid (SAC): A literal translation of Camelidos Sud Amer- similar average fiber diameter (AFD). icanos, incorporating all the members of the Lama genus, including the alpaca, llama, guanaco, and vicuña. Sample Demographics Transmission Electron Microscopy (TEM): Use of the electron microscope Samples were collected from 35 suri to view an object on-end, rather than on the surface of the subject. alpacas, comprised of 20 male and 15 females. Thirty of the suris were 158 ■ Alpacas Magazine Most of the straighter fiber samples had excep- tional luster and a low MSF. The narrow flat lock was highly correlated to luster in this study. offspring from the 1991, 1996, and “Yocum-McColl” sample site used for 1998 Bolivian importations to the laser scanning. The second phase of USA. These animals were randomly fiber samples had a slightly lower MSF selected from our own herd based on than the first. Twenty of the suri whether we had fiber samples or fleeces alpacas had a uniform age range of 11 saved from the previous year’s clip. to 13 months at the time of sampling. Three Australian suris were also tested. Eight samples from Phase 2 were sec- These were first-generation suris from a ond or third fleeces, rather than virgin suri x huacaya cross that were pheno- fleeces (and these animals were three to typically suri. Two more of our suris five years old). Three of these could be were from Peruvian origins. Fiber sam- compared to the same animal’s virgin ples were collected in two phases. The fleece. MSF was within +/- 10% of the first phase of 14 samples was collected virgin fleece. No significant difference from shorn virgin fleeces. The remain- was noted between the first and subse- ing (majority) of samples were taken quent fleeces. The remaining seven A well-locked suri in his second fleece, like from unshorn suris using a uniform animals were 21 to 25 months old. this animal, typically had an MSF of 7-7.5. Spring 2006 ■ 159 According to ARI statistics, over half of measure the length of each scale on a all suri alpacas in the United States are fiber, the height of scale, frequency of colors other than white. About two-thirds scale, angle of scale, and fiber diameter. of this study were colored: eleven subjects For the purposes of this article, the rel- were white, eight brown, seven black, atively simple International Wool Tex- five fawns, three greys, and one beige. tile Organization (IWTO) DTM-XX-97 The majority of samples (21) had a methodology was used with the excep- twisted style of lock, including several tion of viewing the samples at 1,000 X with a highly-evolved “pearl” lock of magnification rather than 600 X. The 3-4 very small inter-twined locks. The higher magnification was necessary for style of lock ranged from cotted to accurately measuring suri scale height, “independent.” The remaining samples which is almost impossible to measure had either a narrow flat lock (3), a rela- even with digital imaging tools. Wool tively straight fleece that clung closely has a scale height of <8 micron and can to the body (6), a fan-shaped lock (3), easily be measured at 600 X. or a coiled (corkscrew) lock (2). Four Measuring scale height is important, Dr. Chris Davitt, PhD, with sample dishes in of the donors were overweight, and since scale height is one reason suri front of her Scanning Electron Microscope in these had the strongest Average Fiber alpaca fiber has a low coefficient of Pullman, Washington. Diameter (AFD). The samples were friction and feels finer than it is. laser scanned and had an AFD of Following IWTO DTM-XX-97 16.7-32.8µ with a mean of 22.8µ and methodology, the authors counted the 10.3% coarse fibers. All of the subject number of cuticular scales in a 100 animals were healthy, de-wormed, body micron field of view. Scale frequency is score condition 7-9, and compared to expressed as a Mean Scale Frequency A 13mm long fiber sample is attached to the the population at large, free of heat (MSF). A lower MSF indicates a longer SEM stub with electrically conductive tape. stress (we shear). None of the donors cuticular scale. A higher MSF indicates had ever been washed with shampoo a series of shorter scales. A literature or conditioners. search revealed that an MSF for wool ranges from 10-12, depending on Why SEM? breed, 6-8 for de-haired cashmere, and The SEM micrographs provide detail 6-7 for de-haired mohair.3 Some care is not obtainable with a conventional required to achieve consistent results compound microscope. An optical using IWTO-97 methodology. A varia- The golden fleece! Fiber samples have been microscope uses visible light of a wave- tion of 10-30% was possible. depending coated with 20-30 Å of pure gold prior to being length of several thousand angstroms on where you counted the scales. Wool viewed by the Electron Microscope. (Å). Such an instrument is actually a and huacaya alpaca could easily be photon microscope, since a ray of light counted on the edge of the fiber sam- is a beam of photons. An electron ple, but suri – which has virtually no microscope uses a beam of electrons scale height – was most easily counted instead of a beam of light. down the center of the fiber. Using The main advantage of the EM micro- Adobe Photoshop to open the micro- scope is its potential for very high graphs, huacaya scales could be count- resolving power. This is based on the ed viewing the micrograph at 50% possibility of using electrons whose de actual size, while suri required viewing Broglie wavelengths are less than 1Å. at 66-200%. We standardized on Objects as small as 2.3Å have been counting scales on the left edge of the resolved, a feat forever beyond the capa- sample viewing it at 100% actual size. bility of a microscope using visible light.1 Very precise measurement of fiber diameter, scale length, height, and scale Research Methodology edge angle, can be accomplished using Micrographs were taken at an accelerat- digital imaging software. We tried ing voltage of 15 Kilo Volt (KV) and Scion Corporation’s Image for Windows, The Long Smooth Scale™ of suri fiber can 1,000 X. The quality of the micrographs and Image-J software, which is available clearly be seen in this micrograph. Average scale length was 16.25µ. The debris in back- taken by a skilled EM instructor like Dr. as a free download by the National ground is dandruff. Davitt made it possible to accurately Institutes for Health (NIH).