by Margaret Flowers

Icelandic sheep. What are the selling points? Although, of course, we know that they are useful for much more, like property services, we talk about these sheep as “triple purpose”: lean, delicately-flavored meat, rich milk, and a versatile, luxurious fleece. As an almost life-long knitter (my mother had me knitting before I went to Kindergarten!), and later a weaver and spinner, the possibilities of uses for these fleece (to separate or not to separate the coats; to ply or not to ply; to spin worsted or woolen...) was something that I found fascinating.

What started as idle curiosity...

I was curious about what exactly the fleece looked like, in a mathematical sense. In the world of Shetland sheep breeders, it is customary to have animals micron-tested, as “fine” fleece is a part of that breed standard. So several years ago, when I was packaging my Shetland samples for testing at Yocom-McColl Testing Laboratories Inc., I found myself wondering: How did the Icelandic fleece compare? So along with my Shetland samples, I sent samples from four unrelated/ distantly related Icelandic sheep ranging from 3 to 5 years old. (Samples are 2” x 2”, taken from the side. Tests are done across the provided sample from a cut taken near the base; http://ymccoll.com/ micron_reports.html.)

While the Shetlands had a wide range of micron profiles, there was a remarkable similarity in the Icelandics. These results were a bit stunning until I thought it through. It was understandable that there would be variation in the Shetlands because there had been some cross-breeding with Merinos, etc. in the 18th and 19th centuries, and there are different “fleece types” within the breed that reflect this history. The Icelandics, however, remaining pure for over a millennium, showed little variation. Mean fiber diameter (MFD) was between 27.7 and 29.2μm; with standard deviations ~10 μm, and the percent of the fibers over 30 μm ranging from 27.3–33.2%. Illustrated are micron data produced for Dancing Lamb Hani and Trinity Askja.

In addition to the histograms illustrating the percent of fibers at each micron, the information on MFD and the percent of fibers greater than 30 μm are important in comparing one animal to another. For a dual-coated fleece like the Icelandic, the standard deviation and coefficient of variation measures would be expected to be high.

Knowing that the Icelandic fleece is composed of a layer of fine thel and several layers of tog (Abbott, 2001), it is possible to estimate the “peaks” of several layers (assuming a bell-shaped curve for each layer). The tog peaks that overlap the thel and each other can be visualized as “shoulders” on the curve. The outer-most tog averaged 45–48 μm; intermediate tog, 35 μm; the innermost (and finest) tog layer, 29 μm, and the thel averaged 22–23 μm.

...that led to getting myself in pretty deep!

I had more questions. We know that the fleeces of Icelandic sheep are not created equal! We can feel that the “hand” of the lamb fleece is softer than that of an adult. How is this reflected in the micron test histograms?

But beyond that, there are lines/sub-breeds of Icelandics that are available to breeders in North America: the typical “commercial” meat sheep, the leader sheep, and the “pelt” sheep. In Iceland, the typical sheep have been selected primarily for meat characteristics recorded in the BLUP scores, and only secondarily for wool. The leadersheep represent a primitive type, selected primarily for behavioral characteristics of alertness, leading ability, etc. and the accompanying physical characteristics. They have been characterized as having a “shaggy” coat (Eythorsdottir, 2015). Selection for the wool quality found in the pelt sheep began in 1980, and sheep of this type are quite scarce in Iceland. Again, they have not been bred with meat in mind; in fact, there is a cautionary statement in the Southram catalogs, just as for leadersheep, that the pelt sheep will not improve growth rates. These sheep, bred with fleeces as the primary “purpose,” have only recently become available to breeders in the US. So with three distinct goals of breeding, what might be the variation in the fleece among these?

At fall shearing time in 2017, I took mid-side samples of sheep to answer these questions. I controlled as many variables as I could: all the sheep were female; for the sub- breed study, all were of approximately the same age (born within an 11-day period) – approximately 18 months of age; and all had been housed and pastured in the same group, so had access to identical food. For the age comparison, I also took samples of a lamb and an adult, as well as a yearling, all of the “commercial” type. All sheep were F1 daughters of AI sires from Iceland.

Age Differences

For age comparison, I selected Myra, 6-month old horned moorit-mouflon daughter of Grámann, as the lamb representative; Grimsey, yearling (18-month-old) polled gray, daughter of Höttur; and Hamra, a 30-month-old black-gray daughter of Salamon as the adult.

As the results provided are scaled to fit the paper, the scale of the y-axis (Percent of Observations) and the x-axis (Fiber Diameter – microns) may be different for different samples (see Hani and Askja, above). I adjusted these dimensions so that the scale is identical for each.

It was not a surprise that Myra’s lamb fleece is demonstrably softer than that of older animals. This is shown not only in the mean fiber diameter (MFD), but also in the percentage of fibers that are over 30mm in diameter (~11% for Myra and ~18% for Grimsey and Hamra), a measure important in selection of the use of the fiber (e.g., next-to skin vs. outerwear). From the graphs, we can see that about 70% of Myra’s fibers are less than 20 μm, while only about 40% are less than 20 μm in both Grimsey’s and Hamra’s. Similarly, the fiber diameter of the tog layers is lower in Myra’s fleece (~22, 30, and 38 μm) as compared with Grimsey’s and Hamra’s (~26, 32, and 45 μm). In addition,
the number of fibers in the inner tog layers of Myra’s fleece seem to be fewer than in the older sheep. One surprise for me was the similarity between the yearling (Grimsey) and adult (Hamra) samples. The inner tog layers (24-26 μm range) seem to have fewer fibers in the Grimsey’s fleece, but they are in the same diameter range in both. From the the initial tests of the older sheep (e.g. Hani and Askja), it can be expected that the coats of these sheep becomes coarser with age.

Different “sub-breeds”

Now what about the yearlings that were bred with different “purposes” in mind? I chose Grimsey to representing the “commercial” sheep of the breed, a polled gray, daughter of Höttur (see the earlier picture); Katla, a leader ewe (94% leader genetics) with the classic markings of black with white blaze and socks, ( and daughter of Geri; and Sota, a black-gray badger, daughter of Grafeldur, the “pelt-sheep” AI sire. As with the age comparison, I adjusted the graphs to make the scales identical. [NOTE: SInce the publication of this article, Icelandic Leadersheep have been determined to be a breed separate and distinct from the “usual” Icelandic sheep. (Newsletter of the Icelandic Sheep Breeders of North America - Summer 2019 Volume 24, Issue 3, Pages 19-29).]

Here was a big surprise! The MFD for all three “types” was extremely close: 24.2–24.6 μm, and the percent of fibers over 30mm ranged from 16.1–18.2%, again quite close. This is reflected in the appearance of the graphs of the distribution of fiber diameters. What I would have predicted was a coarser fleece in the leader Katla, especially in the tog, and a much finer than average fleece in Sota, the “pelt” sheep. Yet, the thel was remarkably similar, with peaks at 17–18 μm, but with Sota having more thel fibers. The outer tog (44–46 μm peaks) was also similar, although Katla did not have any extremely large tog fibers, probably accounting for the lower percentage of fibers over 30 μm. The biggest difference can be seen in the inner tog layers; more numerous and a bit coarser in Katla’s fleece. Perhaps this is what gives the leader fleece the “shaggy” appearance.

What the results tell us...and what they do not.

The laser scans of fiber diameter performed by Yocom-McColl are a powerful tool to analyze the fineness and overall structure of a fleece – information useful in comparing one animal with another, and ultimately determining the best use of the fleece. Is it uniform or with several coats? Is it very fine and perfect for next- to-the skin wear, or is it better suited to outerwear, or even rugs? What this doesn’t tell us is (for example) the density of the fleece, or its length. It doesn’t tell us that Katla’s yearling fleece was the identical weight of Grimsey’s, and that Sota’s fleece was 20% heavier than either... or that Sota’s was both denser and longer.

Now, granted, except for my initial burst of curiosity, I did not have samples analyzed for more than the smallest possible sample size. So there is no doubt that with a sample of one, it is impossible to see the entire range of variation in the group that each represents. However, the overall similarities shown by graph and by statistical analysis of the fiber sample of each animal point to a unifying pattern: these are Icelandic fleece. Over a thousand years of breeding divergence in the case of the leadersheep, or almost 40 years of intensive breeding in the case of the “pelt” sheep has served to slightly modify, but no way obscure, the many coats of the Icelandic sheep.

Literature Cited:
Abbott, Elizabeth, 2001. The Icelandic Fleece: A Fibre for All Reasons.

Eythorsdottir, 2015. <https://www.youtube.com/watch?v=YmP_f9-0Y7E>.

Originally published in the Newsletter of the Icelandic Sheep Breeders of North America - Winter 2019 Volume 24, Issue 1 , Pages 11-16