Blyth, Janet S. S.

2018-01-31T11:46:37Z

2018-01-31T11:46:37Z

1925

In connection with a sheep hybridising experiment which is being carried cut by the Animal Breeding Research Department, a microscopical analysis of the fleece of the parental breeds involved (viz. Scuthdown and Blackface Mountain) was undertaken. It was hoped in this way to make a complete survey of all British breeds, describing in the first place those which are most frequently used for crossing on account of their greater value in the study of the inheritance of fleece characters. However, this study had not long been commenced, when it became evident that if the original method of examining each breed separately and thoroughly in sequence were adhered to, while useful data would be collected in large numbers, much of the significance of such infcrmat ion would only be exposed at the end of the investigation, or indeed some points would be entirely lost sigh of if they were not accentuated until some breed towards the middle of the series was reached. Moreover, the time required to carry cut the work on such a scale would stretch over many years.

Accordingly, the position was reconsidered and it was decided that the quickest way to optimum results lay in first carrying out a breed survey on the smallest scale compatible with reasonable accuracy in general and basic results. Such a study would at least present a bird's eye view of the situation and would, in all probability, show or suggest more specific lines of research which might be followed with advantage.

The work was carried out at the Animal Breeding Research Department, the University, Edinburgh, and my best thanks are due to Dr F. A. E. Crew, Director, for the facilities and opportunities afforded to me during the course of this investigation. I am very deeply indebted to Professor Barker, University of Leeds, for his kindness in supplying me with most of the wool necessary for this study.

1. Two main types of fibres occur in British breeds of sheep. Type I is proportionally the longer and coarser and exhibits c iaracteristic scale markings. It appears to occur only in the Lustre and the Mountain Longwool groups of breeds. Type II ir shorter and finer and possesses a coronal type of scale marking; it occurs in all breed groups. It constitutes the main type in the Short Wools, is present in varying proportion in the Mountain Longwools and the Lustres. In some samples of the latter group, however, its component fibres are very few in number.

2. Two small subsidiary classes of fibres are also found. Kemp, the coarsest type, is present in all breeds. It is shorter than the main types and is shed periodically, being usually found l ir.g loosely in the fleece with a complete tip &nc root. The other small group consists of very fine short fibres similar in structure to the finest members of type II. They were only identified in a few of the samples, but it is possible that they were present in all breeds but were not separable from type II.

3. Type I and kemp are considered to be homologous with the hair of the primitive breeds of sheep, while the primitive wool is represented in modern breeds-by type II and the small group of fine fibres.

4. Medulla. varies greatly even within individual breeds. It has a greater tendency to appear in the homologues of primitive hair than those of wool, and occurs more frequently in the Mountain than in the Non-mountain wools. It is suggested that this variability is not wholly due to hereditary influences but is in some measure caused by environment.

http://hdl.handle.net/1842/28377

The University of Edinburgh

Annexe Thesis Digitisation Project 2017 Block 16

Studies on the fleece fibres of British breeds of sheep

Thesis or Dissertation

PhD Doctor of Philosophy