History and Science Of Mereno Sheep

Along with the formation of Western Civilization in the eastern Mediterranean, came the early domestication of meat animals, primarily goats and sheep. Domestic sheep (Ovis aries) were domesticated (perhaps as early as 12,000 years ago) from the European wild sheep (mouflon).

These earliest sheep were a hair type sheep that had a sub-coat of finer denser wool close to the skin. These sheep may have resembled the Barbados Sheep (from North Africa) in appearance and like them, may have shed their inner wool seasonally. Also believed to very closely related to the Mouflon are the Soay sheep which were brought to Soay Island (northwest of the northern tip of Scotland) thousands of years ago by Neolithic seafarers. There they have adapted to the local environment without the intervention by humans. They also shed their inner wool (sub-coat) and tend to scatter when alarmed rather than cluster as other more modern sheep do (http://www.soayfarms.com/history.html).

It was this sub-coat of the first domesticated sheep that interested the early farmers due to its soft and finer characteristics (in addition to supplying meat). Over thousands of years of selection, this sub-coat came to dominate the type of wool in the finer wool breeds.

The original hair was later termed primary follicles and the inner wool was termed secondary follicles. The secondary to primary follicle ratio for today's Merino is approximately 18:1 up to 60:1. Domestic sheep now encompass over 200 distinct breeds distributed throughout the world.

Another breed of sheep that has strong similarities to its early Mediterranean ancestors is the Orkney sheep named after the Orkney Islands from which they are found. Their origins are mostly unknown and at best speculative. These islands are situated off of the northern tip of Scotland. Here, these long wooled sheep graze primarily along the coast where their major diet consists of seaweed. As the first domesticated sheep developed a high tolerance to salt and an efficient system to function on a limited water supply, the Orkney sheep find it easy to adapt to their seaweed diet. For more information concerning the Orkney sheep, see http://www.caithness.org/history/articles/northronaldsaysheep2/.

The long course wool is most often woven into products and the finer wool is spun into garments that can be worn next to the skin. The merino breed (focus of this website) of sheep first developed in Spain and spread into Europe (later to Russia & China), down to South Africa and around the horn to Australia and New Zealand.

Strains of Merino were developed as a result of the spread into Europe. In 1786 a flock of 386 Merino ewes was imported by Louis XVI to France (www.sheepusa.org). This flock adapted to the local conditions and cultural needs and was soon renamed Rambouillet. A Rambouillet ram was a founding sire in the Peppin strain (the major strain) of Merino in Australia. In Saxony (NE Germany) a strain of Merino was developed that concentrated more on wool fiber fineness than on body size.

The Rambouillet became the dominant breed introduced in the U.S. in the early half of the 19th century. It became and remains the dominant sheep breed in the western half of the U.S. and has been bred as a dual-purpose animal (wool and meat). These sheep became very hardy and maintained their flocking characteristics that allowed them to be easily managed in large numbers. Today this strain of Merino may attain sizes 1/3 more massive than its Australian/New Zealand cousins.

Characteristics of Wool

The Autumn Hills Woolens breeding strategy is to produce wool that results in a superior spinning product. The emphasis of this narrative will therefore be directed towards the understanding of the traits that affect the breeding of fine to superfine wool sheep.

There is a limit on how much the physical traits can vary within a species. When traits stray too far from the norm as caused by new environmental adaptations, a new species is created. The genetic latitude within a species is limited and changing those parameters can be difficult. When breeding for certain traits in wool sheep beneficial results are often achieved through trade-offs, some desirable traits gained and some sacrificed. Breeders since the beginning of time have been trying to push against these trade-offs and try to create a new strain that has the best characteristics of both strains.

Traits that are important to the many of the producers of fine wool sheep are

Before delving into these topics, I would strongly recommend an article that is a free .pdf download from the CSIRO website in Australia, "A review of the biology linking fibre diameter with fleece weight, liveweight, and reproduction in Merino sheep" by N.R. Adams and P.B. Cronje (http://www.publish.csiro.au/paper/AR02059.htm). This is one of the best articles I have found on the web that discusses nearly all of the problems associated with the breeding of fine wool sheep.

When most people think of wearing a wool garment most react with an itching reflex, me included.

The fiber diameter in the Rambouillet and Merino breeds vary between 11-26 microns.

Most of the wool lies between the 17 and 24 micron range. A micron is one-millionth of a meter (39.37 inches).

This may seem so small as to be invisible to the human eye, but an untrained eye can easily see the difference between a 20 micron fleece and a 30 micron fleece.

A very important benchmark, which defines the quality of fine wool, is "Prickle Factor". Simply put, fibers that are 30 microns or greater in diameter can be felt by the skin as prickly or itchy.

One of the traits measured when you send a sample of wool in to get tested is the percentage of fibers greater than 30 microns. This percentage subtracted from 100% gives you the Comfort Factor. The best Comfort Factor is 95% or greater, the closer to 100% the better. The smaller the average diameter (FD) is, the easier it is for the overall fleece to achieve a higher Comfort Factor (i.e. the further away the average is below 30 microns, fewer fibers will remain that exceed 30 microns).

Factors Affecting the Fiber Diameter (FD)

The greatest factor influencing the fiber diameter is diet.

Wool fiber is greatly influenced by the amount of protein ingested by the sheep. Scrubby desert brush and grasses have a very low protein content. Alfalfa and fattening up grains (corn, c.o.b. etc.) have a high protein content and can increase the fiber diameter by as much as 4 microns.

Fiber diameter is a highly heritable trait. It can still take several years of selection for the average FD of a good size flock to be lowered by 1 micron but only one season for diet to lower the FD considerably more.

A major problem that most commercial wool ranchers face is that in order to make the operation a financial success, you need to graze the sheep on what is available. This means that the early spring grass is rich in protein and the fall grass is low in protein resulting in a fiber that varies in diameter over its length. If the feed supply varies greatly in protein content then the fiber can loose strength or break easily in the thinner areas. This is where the next two fiber traits become important.

Standard Deviation of the Mean (SD) and Coefficient of Variation (CV)

These are terms that can make many non-mathematically people skip to the next section.

The Standard Deviation figure basically shows uniformity, the lower the number the better.

A low number SD (3.2 or less) will mean that most of the fibers will be very close to the same diameter. Since diet can so greatly affect fiber diameter, the SD will most likely stay the same for the productive life of the animal as long as the type of feed remains the same.

A sheep fed on the same protein content feed throughout the year should have a lower SD number. At first I couldn't figure out why our sheep had so much lower SD numbers that many of the flocks in Australia, which obviously had superior breeding. I finally learned that because we feed alfalfa all year around, the fibers were being nourished by a very consistent feed throughout the year. For the Merino breed, it is recommended that the Standard Deviation not exceed 5 microns.

Crimp

A recent touch test using 800 experienced spinners found that less crimp made 23 micron wool feel softer. Conversely, an 18 micron wool felt softer with more crimp. Also of note, women’s sense of touch was more acute than men’s and sensitivity increased with age (FEMININE TOUCH WINS SOFTNESS STAKES in Department of Agriculture, Western Australia - Winter edition No 5 1999).

The term crimp may be summarized as a trait that gives body to fine animal fiber so that it can be handled and managed by human fingers more easily.

The finer or narrower a group of fibers becomes the harder it is for them to adhere to one another in a non-greasy way, the straight fibers tend to slip by their adjacent fellow fibers. The curl in a fine fiber (not too dissimilar looking from curly human hair) allows each fiber to lock horns with adjacent fibers and therefore through a series of steps be fashioned into a type of fabric or garment.

Fiber curvature and crimp are closely related terms. Their detailed relatedness is a bit too technical (and harder to grasp, myself included) to be discussed here. I believe that crimp can be counted (per inch) and curvature is measured by hi-tech machines looking at angles and rotation. For more detailed information see OBJECTIVE MEASUREMENTS – MORE THAN PRETTY NUMBERS by Peter Sommerville (1998)

http://www.awta.com.au/Publications/Research_Papers/Research_Index.htm.

Crimp is an important fiber trait to Merino breeders in addition to fiber fineness since the number of crimps per inch or centimeter affects the fiber’s utility. Some of the folks that spin ultra-fine Alpaca (Suri) and Angora Rabbit fiber, choose to blend it with crimpy Merino Wool to increase its spinning performance.

Gross Fleece Weight (GFW), Yield and Fleece Rot

The commercial wool producer can't experience much of a profit from his wool if the fleece has little weight. This is why the Merino breed has been bred for a heavy fleece.

The GFW for our pure merino and cross ewes is 14 pounds (6.4 kgs.) and for our rams, 16 pounds (7.3 kgs.). The GFW is the total sheared mass as it falls to the ground from the shearers. From what I have been told by some very kind and knowledgeable folks from Australia, this favorably compares to commercial Merino flocks averages.

A heavy GFW is great but this is not the whole story.

What is important in most cases is how much the fleece will weigh after going through the cleaning process. The great Sire rams can have yield up to 82% (weight of clean/weight of in-the-grease).

What makes up the difference? Vegetable matter, dirt, and skin produced grease, mainly the latter. At first one would think that the higher the number the better, eh? Not necessarily. When I first received many Drop Sire Reports (fiber statistics from top rams) from a mentor in Australia I entered a lot of statistics into my computer spreadsheet. We intend to move in five years from an area which receives 6 inches (152mm) to an area in western Washington State that receives up to 60 inches (1524mm) a year.

I was trying to find out what fiber characteristics are associated with low fleece rot occurrence.

I noticed that the rams that had a low yield (but high in vegetable matter, dirt, and body grease) did indeed have a lower incidence of fleece rot. I mentioned this to my Australian mentor and she replied that yes, this is true. The high level of body grease is referred to as "nourishment" and that it does retard the onset of fleece rot in high rainfall areas.

This "nourishment" is heritable but moderately so. This is how I understand the problem: fleece rot is similar to diaper rash, a bacterial infection affecting the surface of the skin usually in a rain-soaked sheep. The rash oozes fluids that stain the wool in irregular patterns of yellow making it undesirable for marketing. What makes the situation worse are skin wrinkles which retard the skin's ability to dry out. Nourishment either coats and protects from the moisture, or perhaps there are antibiotic agents present in the grease. There does however to be seem to be a strong link between fine wool and fiber nourishment (low yield).

Type of Skin

Before we had our latest crop of lambs I read an article by David Scobie of the AgResearch, Lincoln, New Zealand (see link below) entitled, "Wrinkles lower productivity". It discusses the pros and cons of wrinkly skin.

When our lambs arrived, I nearly panicked, 70% had a lot of wrinkles. I immediately contacted some internet mentors, visited new born lambs of the same breeding, and talked with the local University's expert. On shearing day in mid-March locally, many sheep were sheared that were Rambouillet as well as our Merinos. Many (perhaps 33%) of the Rambouillet lambs had a fair amount of wrinkles and these lamb's dams and sire did not have long staple or heavy fleeces.

For the last couple of hundred years, people have been selecting for a heavier fleece. This pretty much means more wool per square inch. The way that this was achieved was by the development of skin wrinkles, effectively increasing the surface area of the skin while keeping the same animal underneath.

Whether these breeders looked and planned for wrinkles to appear or it just happened that the heavier fleeced animals slowly developed wrinkles as their fleece weights increased is beyond my area of understanding. From the article by Adams and Cronje mentioned above, of the total protein that the sheep body uses for development and maintenance, approximately 15% is allocated to skin development and maintenance. Of this percentage, 20% is allocated for the production of wool. In humans, a higher proportion of protein or muscle tissue is usually accompanied by a lower fat content. In sheep, a similar thing happens. The finer and heavier the fleece (also more follicles per square inch) the less the fat content is in the skin. With less fat, the skin can wrinkle easier. If more protein is allocated to the skin, less goes for meat production. It is all linked to one another in a give and take set of loosely defined genetic rules.

In the early 1970s, Dr. Jim Watts developed a breeding strategy known as SRS or Soft Rolling Skin (http://www.severnparkmerinos.com.au/system/index.html). He found that breeding sheep with soft rolling skin (also thin and pliable) greatly increases the potential for increasing the quality of wool, that is, heavier finer fleeces with a very long white lustrous fibers. The fleece naturally groups into bundles rather than staples. The skin is very pliable. A problem with heavily wrinkled skin that is not soft and pliable is that the animal is not healthy; often smaller in body size with a decrease in fleece quality (see David Scobie, "Wrinkles lower productivity"). There is controversy in the Merino countries down under over wrinkles. In our small flock, after shearing, our new Merino ram (2 year old) did indeed have that SRS type skin. Half of our wrinkly lambs grew out of their wrinkles. Our most wrinkled one (harder wrinkles) is the smallest and tended to be somewhat sickly as a very young lamb (the only one that received antibiotics). We will understand a great deal more about this topic when we get this new lamb crop's fleece tested at the end of the year. For more information on this type of breeding system visit http://srswool.com/breedsys.htm.

Spinning Quality

For the best spinning quality wool, the fiber staple should be at least 4 inches long and a courser fiber diameter is easier to handle (24 to 30 microns). However, with some practice the finest of wools can be successfully spun producing superior garments (personal communication, Dianne Seldomridge). This finer wool commands a far higher price in the wool market.

Body Weight and the Trade-Offs

To start this last section, I would like to quote a section in the Adams and Cronje article, page 2, "for fine-to-medium wool bloodlines, genotypes with 1 micron lower fibre diameter had on average 8-9% less fleece weight and 4% less body weight".

It was very apparent at the last few University of Reno's ram sales that the pure Merinos were noticeably smaller than the Rambouillet/Merino crosses. Even in our small flock, our smallest hogget (yearling) has the finest fleece. The two year old that had the coarsest fleece (24.8) also had the heaviest fleece of our entire flock (18 lbs./8.2 kgs.) even surpassing our two rams (16 lbs./7.3 kgs.). We have a huge hogget black ram that was 150 pounds at 8 months of age. His fleece was 22.4 microns.

Like many people trying to breed for a superior fleece, we don't want to sacrifice our large bodied sheep. The SRS breeding strategy mentioned above may hold out promise, time and fleece testing will tell.

Some of the very superfine wool breeders in Australia are not concerned with lengthening the staple. They are marketing their wool to Italian wool mills that prefer a limit of 85 mm (3.3 in.). In the future, we will select for narrow fiber diameter, staple length, fleece weight, body size and, a minimum of skin wrinkles. An American expert in the wool field recommended that I should to a large extent ignore the fiber diameter as diet can account for a 5 micron difference and concentrate on lowering the Standard Deviation and Coefficient of Variation numbers. He also warned against getting too much nourishment as it would yellow the fleece unnecessarily. Bright white fleece has a definite market advantage.

I added this narrative to our website to perhaps make it easier for fine wool enthusiasts to understand the statistics used in more technical reports. It took me quite a while pouring through Drop Sire Reports and bugging patient Merino experts before I achieved a moderate understanding of the subject. If any reader finds an error in this essay, please notify me at the email address listed below.