The Biology Topics of biotechnology involves using living organisms to develop new products or solve problems.
Explain the steps involved in the production of wool
Natural fibres are threads obtained from plants and animals. In Class VI we have learnt about some fibres obtained from plants which are used to make fabric (or cloth). For example, cotton plants give us cotton fibres which are used for making cotton fabrics (or cotton cloth). Cotton, flax and jute are all plant fibres. In this chapter we will study about the fibres which are obtained from animals and hence called animal fibres. The two important animal fibres are :
- Wool, and
Wool comes from animals such as sheep, goat and yak, etc., whereas silk comes from silkworms. So, wool and silk are animal fibres. Wool is used for knitting sweaters and weaving shawls and other woollen cloth. Silk is used for making saris and other dresses. We will now discuss the production of wool and silk in detail, one by one. Let us start with wool.
Wool is the most commonly used animal fibre. Wool is the soft, wavy (or curly) hair which covers the body of a sheep. Actually, wool is a modified form of hair that grows with a waviness. Because of the waviness of wool, the woollen fabrics have a greater bulk (than cotton fabrics) and hence trap more air. Due to this, woollen fabrics keep us more warm during cold, winter days. Wool comes from sheep. Actually, wool is obtained from the fleece (or hair) of sheep. Sheep grow wool on their body and once
a year, this wool is sheared (cut off’). Though wool comes mainly from sheep, some other animals also give us wool. This is discussed below.
Animals That Yield Wool
Wool comes from the animals like sheep, goat, yak, camel, llama and alpaca. In other words, the wool- yielding animals are sheep, goat, yak, camel, llama and alpaca (see Figure). The wool-yielding animals bear a thick coat of hair on their body. It is this hair which gives us wool. Actually, the wool-yielding
animals have a thick coat of hair on their body to keep them warm during cold winter season. The hair (or wool) trap a lot of air. Air is a poor conductor of heat. So, the air trapped in hair (or wool) of these animals prevents their body heat from being lost to cold surroundings and keeps them warm in winter. This is why the hair (or wool) of these animals is removed only once in a year at the beginning of summer season. They can survive in hot weather without hair. And by the “time winter comes, the thick hair (or wool) grows again on the body of these animals.
Wool is most commonly obtained from sheep. Sheep are reared in many parts of India for getting wool. The names of some of the breeds of sheep reared in our country for obtaining wool, the quality of wool obtained and the names of states where these sheep are found, are given in the table below.
Some Indian Breeds of Sheep
|Name of breed of sheep||Quality of wool||Name of the state where found|
|1. Lohi||Good quality wool||Rajasthan, Punjab|
|2. Rampur bushair||Brown fleece||Uttar Pradesh, Himachal Pradesh|
|3. Nali||Carpet wool||Rajasthan, Haryana, Punjab|
|4. Bakharwal||For woollen shawls||Jammu and Kashmir|
|5. Marwari||Coarse wool||Gujarat|
|6. Patanwadi||For hosiery||Gujarat|
The hairy skin of sheep has two types of fibres that form its fleece (or wool coat):
(i) the coarse beard hair, and
(ii) the fine, soft under-hair, close to the skin. The fine hair provide the fibres for making wool. Some breeds of sheep possess only fine under-hair. Their parent sheep are specially chosen so as to give birth to sheep which have only soft under-hair. The process of selecting parent sheep for obtaining special characteristics in their offspring (such as soft under-hair) is called ‘selective breeding’. The natural colour of wool is generally creamy white though some breeds of sheep produce wool having brown and black colours.
Wool is also obtained from ‘goat hair’. The under-fur of Kashmiri goat is soft. It is woven into fine shawls called ‘Pashmina shawls’. Angora wool is obtained from Angora goats which are found in the hilly regions such as Jammu and Kashmir. Yaks have thick and long hair on their body which yield wool. Yak wool is common in the hilly regions of Tibet and Ladakh. The hair (or fur) on the body of camels are also used as wool. The animals called llama and alpaca (which are found in South America) have hair on their body which are processed to yield wool. Please note that though the hair on the body of animals such as sheep, goat and yak, etc., constitute wool, but in everyday language wool means the ‘processed wool’ which is the ‘wool yarn used for knitting sweaters or making shawls, etc.
Production Of Wool
Wool comes mainly from sheep. In order to obtain wool, sheep are reared and bred; their hair is cut and processed into wool. We will first discuss the rearing and breeding of sheep, and then describe how the sheep’s hair (called fleece) are cut and processed to make wool (or wool yarn).
Rearing and Breeding of Sheep
Rearing of sheep means to look after the sheep by providing them feed (food), shelter and health care. The persons who look after the sheep (or rearers) are called shepherds. Sheep are herbivores and prefer to eat grass and leaves. So, shepherds take the herds of sheep to countryside for grazing. Apart from grazing grass, the sheep are also fed mixture of pulses, corn, jowar, oil cakes (oil cake is the material left after the extraction of oil from oil-seeds), and minerals. In winter, sheep are kept indoors and fed on leaves, grains and dry fodder.
Certain breeds of sheep have a thick coat of hair on their body which yields good quality wool in large quantities. These are called sheep of good breeds. Such sheep are ‘selectively bred’ by choosing at least one parent sheep of good breed. So, the breeding of sheep is done to obtain such breeds of sheep which yield good quality wool in large quantities. This raises the quality and quantity of wool produced.
Once the reared sheep have developed a thick coat of hair, the hair is cut off for getting wool. The cut off ‘wool coat’ of a sheep (alongwith a thin layer of skin) is called fleece. The fleece consists of soft woollen fibres. The fleece of sheep is usually kept in ‘one piece’.
How Wool is Obtained From Sheep
The ‘yarn’ which we use for knitting sweaters or weaving shawls, etc., is called wool. Wool is obtained from the sheep by a long process which involves the following steps : Shearing, Scouring, Sorting, Dyeing, Combing and Spinning. We will now describe all these steps for obtaining wool, one by one.
(i) Shearing. The hair of sheep alongwith a thin layer of skin (called fleece) are removed from the body of sheep. The process of removing hair (or cutting off hair) from the body of a sheep in the form of fleece is called shearing (see. Figure). The hair of sheep are cut off by using a cutting machine similar to that used by barbers. The hairy skin of sheep is removed in ‘one piece’ (and it is called fleece). Shearing does not hurt the sheep because the uppernwsf layer of the skin of sheep is ‘dead The shearing (cutting the hair) of sheep is done in the hot weather of summer so that sheep may survive without their protective coat of hair. The hair of sheep grow again before the onset of winter and protect them in cold weather. The fleece (or hair) of sheep provide woollen fibres. Woollen fibres are then processed to obtain woollen yarn.
(ii) Scouring. The fleece of sheep (or cut hair of sheep) contain dust, dirt, dried sweat and grease, etc. So, the fleece must be cleaned before it can be processed into wool yarn. The fleece (or sheared hair) of sheep is thoroughly cleaned by washing with soap (or detergent) and a lot of water in tanks. The process of washing the fleece (cut hair of sheep) that removes dust, dirt, dried sweat and grease is called scouring (see Figure). Scouring makes the fleece of sheep clean. The scoured fleece (or washed fleece) is then dried.
(iii) Sorting. The wool is not uniform in all the parts of fleece of a sheep. Some parts of fleece have fine Figure. Scourinq (washing cut hair of sheep or wool fibres whereas others have coarse wool fibres. ‘fleece’ with soap in a tank). Some parts of fleece have long wool fibres whereas others have short wool fibres. So, the fleece of even same sheep has wool of different qualities. In sorting, the fleece is sent to a factory where it is broken and separated into sections of different quality fibres. The process of separating the fleece of a sheep into sections according to the quality of woollen fibres (such as fine, coarse, long, short, etc.) is called sorting. Every section of wool obtained after sorting contains the same quality wool (or uniform wool). The same quality wool obtained from the fleece of large number of sheep are then mixed together.
(iv) Dyeing. The natural fleece or hair of sheep (or goats) is white, brown or black in colour. The white
woollen fibres obtained by sorting can be dyed in different colours.
(v) Combing. Combing is a method to prepare woollen fibres for spinning the yarn. This is done by using combs having metal teeth. The process of combing straightens the entangled woollen fibres and also removes the small fluffy fibres (called ‘burrs’) which may be caught in them.
(vi) Spinning. The long woollen fibres are spun (dr twisted) into thick yarn called ‘wool’ (which is used for knitting sweaters, etc.). The short woollen fibres are spun into line yarn and then woven on a loom to
make woollen cloth (like shawls, etc.).
From the above discussion we conclude that the sheeps hair is sheared off from the body, scoured, sorted, dyed, combed and spun to obtain wool (for knitting sweaters) and woollen yarn (for weaving woollen cloth). The quality of woollen cloth depends on the breed of sheep from which wool is obtained.
Wool industry is an important source of livelihood for many people in our country. The people who do the job of sorting (separating) the fleece of sheep into fibres of different qualities are called ‘sorters’ The sorter’s job is very risky because sometimes they get infected by the bacteria called ‘anthrax’ which cause a deadly blood disease called ‘sorter’s disease’ The risks faced by people working in any industry due to the ‘nature of their work’ are called occupational hazards. Sorter’s disease is an occupational hazard.