By-Products of Sheep


Sheep are among the most versatile of all domesticated animals. They are very efficient ruminants and a provider of a natural fiber, wool.         




   Wool is the most valuable by-product of meat animal production. It is by far the most used natural animal fiber for fabrics. It is a reliable and increasingly versatile fiber that, when woven into cloth, contributes to warmth and an attractive appearance.


   Wool has been used for clothing and other fabrics for over twelve thousand years. Today, essentially every wardrobe contains woolen garments, plus garments that contain wool along with some other natural and or synthetic fiber.


   The U.S. wool industry today is small compared to that of the leading countries of Australia and New Zealand. For example, Australia traditionally maintains a sheep population of more than 120 million sheep, with production of over a billion pounds of scoured wool annually. The small country of New Zealand ranks second, with an annual production that approaches almost 50 million sheep and 470 million pounds of scoured wool.


*Scoured wool- refers to wool that has undergone a cleaning process that removes the grease and foreign material.



   In contrast, the number of sheep shorn in the United States in 2000 totaled about 6.43 million head and raw wool production amounted to about 28 million pounds on a scoured wool basis. Today’s U.S. wool production is about one-third of the total produced in 1970. This is primarily due to the fact that American consumers favor a meat-type lamb and breeding animals have been selected primarily for meat rather than wool production.


   Currently, about 90% of the wool used by U.S. mills is used as apparel wool in the production of worsted and woolen fabrics. American sheep producers provide about 20% of the total, the balance being imported primarily from Australia and New Zealand.


   Now that you have had an overview on wool, you can click any of the following topics to view a bit more detail:



* Characteristics of Wool


* Wool Quality and Grades


* Wool Processing


* Global and U.S. Production of Wool


* Merchandising and Promotion




Characteristics of Wool


A single wool fiber may be from 18 to 41 microns thick and 1 and ½ to 5 or more inches long.


WOOL IS ELASTIC. It can be stretched 30% or crumpled tightly, and will recover its natural shape rapidly. This property becomes a built-in characteristic of fabric that has a high percentage of wool. It may be wrinkled, twisted, and stretched, but will regain its shape if allowed to hang overnight.


WOOL HAS CRIMP. This natural wavy appearance adds to its effective elasticity, but also provides other advantages. Crimp prevents the individual fibers from lying close to each other in cloth. This produces a bulky effect with tremendous insulation value. Depending on texture and fineness of the fiber, from 60%-80% of the volume of woolen fabric may be air.


Each wool fiver has an outer layer of flat, scale-like cells which overlap like shingles and which are covered with a thin membrane. This is known as the epidermis. This membrane repels rain, but water vapor can penetrate it. The protein cells in the center of the fiber absorb the moisture, which may penetrate the membrane. This is known as the cortex. This property allows water-soluble dye to react with the proteins so the color becomes an integral part of the fiber.


WOOL IS STRONG. It is often said that a single wool fiber is stronger than steel of the same diameter.






Wool Quality and Grades


   The attributes of wool include fineness, length, crimp, color, strength, uniformity, and in grease wool, percentage of foreign material. Fineness is considered the most important.


   The spinning count and blood systems are used for grading wool according to fineness. The spinning count system is the basis of percent USDA grades, even though the blood system is well known and used. The USDA does not provide a grading service, but the standards are used as guidelines in virtually all buying and selling. Originally, the blood system was an indicator of the fraction of Merino breeding in the animal from which the wool came. Since the development of other distinct breeds, the original blood system simply has been adapted to describe relative fineness.

Fineness is important because it allows the spinning of a finer yarn, tighter weaving of cloth, and production of lighter fabrics and garments, Fine wool often has more crimp, too, another attribute of wool quality. Crimp helps individual fibers cling together during spinning, so that a strong yarn can be woven with fewer fibers lying parallel, Crimp, then, also contributes to lighter-weight garments and more efficient wool use. Fine wool often has fifteen or more crimp per inch; coarser wool has less. Wool from the back usually has more crimp than wool from the thigh.


Length of fiber is a quality factor. Though fine fleeces usually have relatively short fibers, the longer the better. “Combing wool” is long enough that regular combing machines can sort and straighten the fibers to make worsted yarn, which is smooth and used for light, high quality cloth. “Clothing wool” is not long enough to be handled even by special combing machines. This wool, therefore, can only be carded and is destined for use in tweeds and other fuzzy fibers. Extremely short wool, from young lambs or extremely old ewes, is often called “scouring wool”. Since it cannot be effectively combed, it may be used for felt or similar materials.


Traditionally, experienced buyers and sellers, who rather accurately estimate fineness, length, shrinkage, and other quality characteristics, have appraised wool quality for sale purposes.





Wool Processing


At the mill, each fleece is pulled apart and sections of the fleece are sorted according to fineness, length, and other characteristics.


All wool is washed in several tanks of hot soapy water, rinsed and dried. Lanolin is recovered from the washings, purified, and sold as a base for face creams and similar items.


Next the dried wool passes to carding machines where revolving cylinders covered with fine wire teeth remover burrs, straw, and similar matter and straighten and comb the wool into a thin veil or web.


From this point on, processing depends on diameter and whether woolen or worsted yarn is to be made. About half of the apparel wool in the United States is used in worsted fabrics.


*Woolen yarn- generally made of shorter and thicker fibers that may lie in all directions, to produce thicker, fuzzier fabrics, such as tweeds.


*Worsted yarn- yarns of longer, finer fibers, so the fabrics will be lighter and have a harder, smoother finish.





Global and U.S. Production of Wool 


   Currently, world production of clean wool is about 3.14 billion pounds, which amounts to slightly more than three-fourths of a pound per person. The leading countries in wool production traditionally are: 1) Australia 2) New Zealand 3) China 4) Former Soviet Union and 5) Uraguay. These five countries represent about two-thirds of all world wool exports each year.


   About 80% of the world production is apparel wool, used for clothing and similar fabric; designated as combing, French combing, or clothing wool. The remainder is carpet wool, used for rugs, carpet padding, and similar materials.

   Wool production within the United States has steadily declined. Consequently, the needs of wool mills greatly exceed domestic supplies. However, the value of U.S. wool produced annually amounts to aver $29 million and wool sales are particularly significant in the leading states: 1) Texas 2) Wyoming 3) California 4) Montana 5) Colorado. These five states accounted for about 51% of all U.S. wool produced in 2000.



   Here is a look at the way things are handled in a couple other countries as far as how wool is marketed:    (Australia)    (United Kingdom)    





Merchandising and Promotion      


   In recent years there has been considerable use of wool in combination with other fibers. Because wool is a stable fiber of long-standing and good reputation, there is a natural tendency for apparel manufacturers to advertise garments containing any percentage of wool as “woolens”.

   Merits of wool as a fiber, alone in fabrics or in combination with other fibers, have caused garment manufacturers to promote wool and wool products aggressively. The Wool Bureau, Inc., of New York is an industry effort in wool and wool product promotion. It sponsors national advertising, helps individual companies with advertising of woolens, provides considerable educational material on wool, and contributes money to other wool promotion groups.



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