Kemp Fibres Research Articles

A Comparison of the Tensile Properties of Kemp, Mohair, and Wool Fibers

A comparative study has been made of the breaking strength and extension-at-break of mohair, kemp, and wool fibers. The results point towards the presence of material in the medulla of kemp fibers, which does not contribute significantly towards the breaking strength of the fibers but which has a dielectric constant comparable to that of the rest of the fiber. Breaking strengths of kemp and mohair fibers are significantly higher than those of merino and German merino fibers.

Coat structure and seasonal shedding in goats

Monthly coat and skin samples were taken from three goats for one year in Australia, and from six others for two years in Scotland. The coat appeared to have a simple cycle of active growth in summer followed by inactivity in winter.The kemp fibres of the outer coat formed brush ends at about the time of the autumn equinox and remained dormant until late spring. Follicles developed first in the foetus formed a brush first. No moult was obvious because new kemps grew before all the old ones had shed, the only manifestation of shedding being a shortening of the coat. The old wool tended to be lost before growth of the new, so that wool was completely lacking in the coat during summer.Observations on skin sections showed that the majority of both kemp (primary) and under-wool (secondary) follicles become active immediately after the longest day, although there was a tendency for re-growth of wool fibres to be delayed, particularly in females.Whereas the proportion of kemps with brush ends during winter reached 100%, the proportion among wool fibres was as low as 50%. A complete explanation for this is not yet evident. The bad winter of 1963 apparently caused a greater proportion of secondaries to form brush-ends earlier and to remain inactive longer.Details are given of some of the histological features of brush formation.

Carding and Combing of Mohair

The removal of kemp fibers during the carding of mohair has been studied. Selective kemp collection by the card clothing takes place mainly because of the greater centrifugal force acting on the mohalr fibers of higher density, which move to the outer layers on the card rollers, causing a relative migration of kemp towards the card clothing; also, higher roller surface speed increases the kemp collecting power. The strippers show the highest selective kemp collecting power and the workers the lowest. The material collected by the card clothing consists mainly of short fibers. Fiber breakage in carding is less for kemp than for mohair.

Fibre shedding and fibre-follicle relationships in the fleeces of Wiltshire Horn × Scottish Blackface sheep crosses

1. Changes in fleece structure produced by crossing the Wiltshire Horn and Scottish Blackface breeds of sheep have been analysed. Skin and fleece samples were available from lambs and adults of both parental breeds, and from the F1 F2 and back-cross genotypes. For the analysis, three types of fibre: kemps, hairs (both primaries) and secondary fibres were distinguished.2. The frequency of kemp fibres was high in the Wiltshire and relatively low in the Blackface. The frequency of hair fibres was nil in the Wiltshire and fairly high in the Blackface. The crosses were intermediate between the parents. Despite these fibre type changes among the primary fibres there was no difference between the breeds or crosses in follicle population densities or in the relative proportions of primary and secondary follicles.3. Kemp fibres were shorter and finer in the Wiltshire than in the Blackface. In the crosses they were intermediate. Hairs, when present in the crosses, were shorter and finer than in the Blackface. Secondary fibres were shorter in the Wiltshire than in the Blackface but in some of the crosses they were at least as long as in the Blackface. Wiltshire secondary fibres were remarkably coarse and strongly medullated and this notable characteristic was carried over to some extent in the crosses. Throughout the study comparison in these terms was always complicated by fibre shedding.4. Fibre shedding was universal for all types of follicle in the Wiltshire. In the Blackface, primary central follicles appeared to shed their kemp fibres two or three times yearly. For hairs and secondary fibres shedding did not occur more than once per year and the frequency of shedding amongst these fibres was low. In the crosses the frequency of shedding in kemps and the incidence of shedding in hairs and secondaries were higher than in the Blackface. Increases in the incidence and frequency of shedding probably had some effect in decreasing the measurable fibre length in the crosses.5. The mean length and diameters of the different fibre types were usually positively correlated within sheep. In this and other ways there was not much evidence of competition for fibre substrate between the different types of mature follicles, in this material.6. Birth-coat classifications distinguished between the typically smooth Wiltshire and the hairy Blackface birth-coats. Birth-coats in the crosses were intermediate but showed partial dominance of the hairy type.7. The most important of the observed changes in fibre and follicle morphology can be briefly summed up by considering how the Blackface phenotype was modified in the crosses by the introduction of the Wiltshire genotype, viz.(a) The proportion of kemps was increased at the expense of hair fibres. This was brought about by kemp fibres tending to replace hairs in all primary central and in some primary lateral follicles.(b) All primary fibres were diminished in length and thickness; secondary fibres increased in thickness. The general fibre population therefore became more uniform.(c) The shedding frequency of kemps and the shedding incidence among hairs and secondaries were both increased.(d) Follicle population density, follicle group structure and the S/P follicle ratio were unaltered.(e) The degree to which changes occurred in the different crosses was generally proportional to the percentage of Wiltshire-derived genes present.8. The fact that the relative frequencies of kemp and hair fibres could be altered without any concomitant changes in the follicle group pattern showed that a particular follicle type was not a priori bound to produce a particular fibre type. It seems clear therefore that the physiological activity of follicles can be altered genetically whilst their organization within the follicle group pattern remains invariant.

The development of the fleece and follicle population in Herdwick sheep

1. The development of the fleece and follicle population was studied in six Herdwick and two Herdwick × Swaledale sheep on their native farm in Cumberland. Six of these sheep survived the first 14 months of the experiment, and four were kept under observation for a further 12 months. Growth in body weight, body surface area, and area of tattooed squares was recorded and discussed.2. Fibre type arrays (at the mid-side positions) were ‘Plateau’ in all but one of the pure Herdwick lambs, and ‘Saddle’ in the remaining three animals.3. The earliest fibres of the array (halos and coarse super-sickles) were mostly ribbon-shaped in their pre-natal and early post-natal portions, below which they became cylindrical. These fibres were ‘birth coat kemps’ and were shed about 10 weeks after birth. At this time later-developed fibres (sickles and curly-tips) showed ‘crisis thinning’ but did not shed, whilst late curly tips and histerotrichs were not affected. These three groups gave rise to three corresponding groups of fibres in the adult fleece, namely kemps, hairs and fine fibres.4. Two generations of kemp fibres were grown each year, ‘spring kemps’ commencing growth about April and shedding by July; and ‘autumn kemps’ commencing growth in July and forming ‘brush-roots’ in the autumn and early winter, although the majority remain in their follicles until the following spring.5. The majority of the curly tip fibres of the birth coat grow into long hair fibres, which are of hetero-typical shape. In summer they are more or less coarse, and medullated, whilst in winter they become fine and lose their medulla; many cease growth during the middle of the winter period after producing a short length of fine fibre, and commence growth again in the spring. The late curly tip and histerotrichs fibres continue to grow as the fine undercoat fibres of the fleece, without any medullation.6. A large proportion of both primary and secondary follicles shed their fibres during the winter months. When this proportion is sufficiently high this leads to a severe ‘winter break’ in the wool staple. The visible ‘break’ is the result of the combined effect of the winter fining of heterotype hairs and the shedding of some of all types. Fibres traversing the break were found to be either long heterotypes or long fine fibres.7. The adult colour of any individual Herdwick sheep is the result of the interaction of several factors of which the main ones are: (1) later fibre types tend to be less pigmented than early types; (2) less vigorous growth of an individual fibre tends to reduce its pigmentation; (3) a more or less extensive acromelanic pigmentation; (4) the white areas may be affected by various degrees of speckling or roaning; (5) the kemp-like hairs of the face and legs are black at birth, and these are eventually shed and replaced by similar but unpigmented fibres.8. Numerical data on the fibre and follicle population are presented. The mean proportion of the three main fibre types (all sheep, all seasons) was: coarse 18%, medium 25%, fine 59%. The mean adult follicle density was 1012 per sq.cm. and the mean adult S/P ratio was 3·37:1.

Bikaner Wool, A Leading Carpet Wool, and Its Improvement

Eight samples illustrating average and extreme types of Bikaner wool were selected from 28 samples received from the Government Livestock Farm at Hissar, India. These 8 samples were analyzed for fiber types, dividing them into true wool, hair, heterotype, and kemp fibers. Both the benzol test and microscopic cross-sectional images were used in the classification. Fiber thickness, stretched fiber length, and contour ratio were determined for the 8 samples along with the surface scale measurements for the different fiber types.

A Preliminary Report on the Post-Natal Development of the Fiber Characteristics of the Fleeces of Navajo Sheep

Fleece samples obtained from side, thigh, and back of 15 Navajo ewe lambs at periodic intervals of growth ranging from 28 to 364 days were analyzed for percentages of wool, hair, and kemp fibers, and the diameter-distribution of each type of fiber was measured. Samples at 28 days of growth contained an average of approximately 60 per cent wool, 24 per cent hair, and 15 per cent kemp fibers by count. During the next 56 days wool fibers increased 21 per cent, while hair and kemp fibers decreased 9.5 and 10.5 per cent, respectively. From 84 to 364 days proportions of the three types of fibers remained relatively constant. Side, thigh, and back samples followed the same trend in fiber development. Differences between lambs were greatest at 28 days of age, but decreased rapidly during the next 56 days and to a limited extent thereafter, which suggests the influence of genetic factors. Highly significant differences were found between sheep, positions, and ages in percentages of wool, hair, and kemp fibers. Age differences were due to sharp changes in fiber content of the fleeces during early months of growth. The diameter-distributions of wool and hair fibers did not change significantly during the year, but kemp showed a significant change in this respect between the 28 and 56 day samples. The significance of these facts is not clear at this time. The study should be continued in conjunction with carefully planned breeding tests.