Last update: April 2, 2012 01:51:30 PM E-mail Print

 

Wool research in South Africa conducted under the auspices of the Department of Agriculture

Part 1 - 1920-1950

 

Dr C.M. van Wyk

Former Chief Director,

Animal Husbandry,

Department Agricultural

Technical Services

 

 

1. The pioneer of wool research in South Africa was Professor J.E. Duerden, professor of zoology at the (then) Rhodes University College in Grahamstown. During the 1920's he and his post-graduate students commenced a study of the Merino fleece. From 1924 to 1933 he was author or co-author of no fewer than 33 papers on this subject in addition to those of his co-workers who were guided by him. Official recognition of his work resulted in his being appointed Director of Wool Research for the Union of South Africa. This appointment was in addition to his professorship and is believed to have carried a small emolument and an allowance for equipment and materials provided by the Department of Agriculture.

1.1 The work of Duerden and his co-workers included studies of fibre growth and the distribution of fibre attributes within the staple and within the fleece. Some interesting results which may be mentioned are: the discovery of the heterotype fibre, the establishment of the high correlation between fibre length and fibre diameter within a Merino wool staple and the postulate that the wavy form of the crimps in wool is caused by spiral growth of the fibres and the flattening of the spiral form by lateral pressure.

1.2 Duerden will, however, probably be best remembered for two reasons. The first was that he devised the technique of cutting wool fibres into short fragments for diameter measurement. This method allowed for thorough mixing of the fragments by shaking in a liquid, thereby simplifying the sampling problem caused by the variation between fibres and along the length of a fibre, which had been the cause of considerable inaccuracy in existing methods of measuring fibre fineness.

At the suggestion of the Wool Industries Research Association, this method was later adopted by the International Wool Textile Organisation as a standard method for the measurement of fibre diameter. Although it became known in the U.S.A. as the Torridon method, the Wool Industries Research Association gave Prof. Duerden full recognition when proposing its adoption.

The second achievement was his compilation of standards of fibre thickness and crimps in Merino grease wools. At the time a quality number was assigned to a sample of wool, ostensibly to indicate the count to which the wool could be spun. This quality number was however arrived at by subjective assessment and probably thereby lost its intended relationship to true spinning count. It did however serve in the trade and industry as a classification of wool according to the main fibre attributes which might be expected to influence spinning performance. By subjecting a large number of samples to appraisal by wool men and measuring the fibre diameter and number of crimps per inch, Duerden compiled a table relating the quality number to the diameter and crimping respectively.

 

 

Although this was not the first attempt to relate fibre diameter or crimping to spinning count, it was probably the first to involve the Bradford nomenclature and to include both diameter and number of crimps per unit length.

These standards have been in use in South Africa since their publication in 1929, in spite of criticism which has been based on a misconception of the object and meaning of the standards. Duerden also emphasised at the time that the standards were not applicable to droughty wool or wool grown on a skin fold.

1.3 What gave the work of Duerden and co-workers particular significance was that both woolgrowers and the Department of Agriculture were at the time engaged on standardising the classing of wool for marketing purposes. The wool classing standards of the newly established National Wool Growers' Association were compiled jointly by that body and sheep and wool officers of the Department of Agriculture. To the latter fell the task of training wool producers in the application of the standards. This was done by means of courses at the agricultural schools and colleges, wool schools on farms, farmers' days and demonstrations on farms. The work of the Duerden group on the distribution over the fleece and the standardisation of quality numbers exercised a profound influence in the campaign. Mention may for example be made of the crimp scale of Duerden and Bosman and the provision of samples standardised by measurement in the laboratory.

 

 

This campaign not only resulted in the standardised marketing of wool in South Africa but also trained producers to evaluate their product in more detail and in this way greatly contributed to the improvement of the South African wool clip.

1.4 On Duerden's retirement the post of Director of Wool Research was abolished and the work was continued at the Grootfontein School of Agriculture by a former student and co-worker, Dr. V. Bosman.

His work comprised a continuation of former studies, but with the emphasis on wool in relation to the sheep, since material was plentiful at Grootfontein. He studied, among others, the wool production of stud Merino sheep, the effect of skin folds, the influence of nutrition and the variation and interdependence of fleece and fibre attributes. In a study of the diameter and crimping of a series of representative wool samples, he found that the relationship between diameter and crimp frequency as suggested by Duerden's table held in only 28% of cases. In other words, an estimate of fibre fineness based on the crimping could be expected to be correct in only 28% of cases.

The main theme of his work and writings was an emphasis on the necessity of employing precise methods in judging the Merino fleece for breeding purposes. He was the first to tabulate the factors which contribute to fleece weight and designed a slide rule with which clean wool production could be readily estimated from quality number (fineness), staple length and number of fibres per square inch of skin. This work formed the basis of modern developments in Merino breeding involving the use of objective assessment of wool attributes.

 

 

2. On the recommendation of Dr. S.G. Barker, Director of Research of the Wool Industries Research Association who visited South Africa in 1929/1930 for a meeting of the British Association for the Advancement of Science, it was decided to establish a new wool research unit. The Veterinary Research Institute at Onderstepoort was chosen as the location of the unit because the Director of Veterinary Services was at the time also Director of Animal Husbandry and there was no separate central institute for research on animal husbandry.

The South African Wool Council defrayed the expense of sending four officers overseas for a year to study wool research. This team consisted of a chemist, a physicist, a biologist and a statistician. The Wool Council erected a building at Onderstepoort for the research unit and also maintained the unit financially for a number of years. In 1934 Dr. Bosman was transferred to Onderstepoort to take charge of the research work. The permanent staff was increased, while additional temporary technical assistance was financed with an annual grant from the Wool Council.

In this way the Duerden tradition, augmented by the research experience at Grootfontein, was linked up with the newly commenced research work at Onderstepoort.

During the ensuing years the scope of the work was extended to include a number of physical properties, such as tensile strength, specific gravity, water absorption and scaliness. A detailed study of the compressibility (or bulk elasticity) of wool was carried out, firstly, because at least as much emphasis was placed on tactual as on visual assessment of wool quality and, secondly, because breeders attached great importance to breeding a fleece closed to atmospheric and other extraneous factors which jointly cause the damage known as weathering.

In this study the compressibility was studied in relation to the following properties and factors: length, diameter, number of crimps per inch, surface friction, tensile strength, specific gravity, harshness, humidity, dipping, skin area, percentage yield, sex of sheep, age of sheep and nutrition. Probably the most significant result to be established was the profound influence of the crimp/fineness relationship on the compressibility of wool in bulk. The expected effect of this influence on breeding and selection over the years has been substantiated by experience. It may be accepted that the undercrimping, high felting propensity and low resistance to compression characteristic of the South African wool clip has to a large extent been the result of the emphasis, in breeding practice, on softness of handle which is regarded as a major constituent of quality.

Among the problems also studied during this period were the effect of sunlight, the effect of feeding level and the effect of season, age, pregnancy and lactation on the wool of the Merino. Studies on the production of the plain type of Merino possibly aided in carrying the pendulum too far in this direction for a while, but they did indicate that breeding for skin folds was not the only method of increasing production. While a certain degree of skin fold development is today regarded as essential for renumerative Merino wool production, it is also realised that a sufficiently high level of production can be maintained without excessive skin fold development with its attendant evils of low fertility and poor constitution.

A study of a technique for determining cystine in wool and of the relationship between cystine and physical attributes was also carried out.

In accordance with Bosman's plea for greater precision in fleece evaluation, a wool testing service was inaugurated. Breeders and woolgrowers were encouraged to send fleeces or samples for the determination of certain physical properties and there is no doubt that during the 30 years in which this service was in operation it not only had a profound educational effect but also had some influence on breeding practice.

3. In 1950 the wool research unit was transferred from Onderstepoort to the Grootfontein College of Agriculture. This provided a closer link between wool research and nutritional and breeding work on the sheep itself. This combined work naturally had a marked influence on the educational and extension programmes.

From this stage on it becomes almost impossible to draw a line of demarcation between research on wool and research on the woolled sheep. It may be mentioned here in passing that in almost every research project on woolled sheep, whether involving breeding or nutrition, a greater or lesser number of physical properties of wool are determined.

4. A short review may also be given of the work done at the faculties of agriculture which are financed by the Department of Agriculture.

At the University of Stellenbosch, Reimers, Swart and co-workers, including postgraduate students, during the 1930's studied the distribution of and correlations between such properties of wool as fineness, crimp frequency and tensile strength and also some aspects of fleece structure. The effect of various elements in sheep rations on the growth and properties of wool were also studied. Changes with age in the fineness of the wool of sheep in parts of the South Western districts of the Cape were also investigated. Lately the emphasis has again been laid on wool in postgraduate studies, for example, in comparative studies of German Merino and South African Merino wool. The establishment of a Department of Sheep and Wool stimulated interest in the study of wool.

During the 1930's, Bonsma of the Agricultural Research Institute of the University of Pretoria and his students studied various aspects of wool, such as the influence of nutrition on wool growth, the sulphur content of Merino wool, the wax and suint in wool and the influence of sunlight and season on wool production. Here too the establishment of a Department of Sheep and Wool has stimulated the postgraduate study of wool. Aspects such as the properties of wool from the Transvaal Highveld, the plasticity of wool, relationship between quality and staple and the influence of nutritional level on follicle development have received attention.

The Faculty of Agriculture of the University of the O.F.S. has had a Department of Sheep and Wool since its inception almost a decade ago. Research work here has been confined mainly to the sheep itself with wool attributes as parameters for evaluating the effect of various treatments.

5. Recently the Research Institute for Animal and Dairy Science inaugurated a fleece testing scheme in addition to the fleece testing service which had till then been provided at Onderstepoort and Grootfontein over a period of 30 years. A building for this purpose was donated by the South African Wool Board. The fleece testing scheme is one of several national performance testing schemes which have been put into operation in accordance with modern trends in animal breeding.

6. The Department has always been aware of the necessity of research on the processing of wool and for a number of years gave an annual grant to the Wool Industries Research Association at Leeds. The Department therefore welcomed the establishment of the S.A. Wool Textile Research Institute and was in fact represented on the Action Committee which was responsible for its establishment. The invitation to officials of the Department to serve on technical committees of SAWTRI is appreciated very highly, as is also the spirit of goodwill and co-operation which exists between SAWTRI and Departmental institutes.

 

Published

Karoo Agric 1 (5), 17-20