Fibre Shedding Research Articles

An Improved Testing Instrument for the Evaluation of the Shedding or Defuzzing of Fibres in Finished Garments

An Improved Testing Instrument for the Evaluation of the Shedding or Defuzzing of Fibres in Finished Garments

Cyclical fleece growth in cashmere goats

Seasonal changes in fleece parameters were studied in mature feral doe goats, known to produce commercial quantities of cashmere and housed in natural light (NL) or continuous light (CL).Circannual changes in volume growth rate (VGR) of cashmere in NL were asynchronous with those of hair, resulting in maxima in April and November respectively, indicating that follicle-specific mechanisms are controlling the rate of follicle activities.Cycles of cumulative length of cashmere and hair in NL were synchronous. Cashmere maxima of 64.0 and 62.3 mm occurred in June and July respectively for two consecutive years. Distinct circannual cycles of linear growth (period, 365 days) were evident. While exposure to CL initially reduced the cycle period, after 2 years an extended cycle period emerged; this may have been due to photodesensitization.In NL, cashmere fibre diameter minima occurred at June-July and February each year. Hair fibres underwent only one cycle of diameter change each year. The period of the cycles was reduced by CL.An annual cycle of cashmere brush end fibre formation was apparent in NL. This cycle was associated with the cessation of growth in June-July, and a subsidiary event occurred between December and March. Continuous light accelerated brush end formation.Cyclic fibre shedding produced a circannual rhythm in fleece composition with maximum cashmere: hair ratio (CHR) in April-May in non-breeding goats. The maximum CHR of 5.9: 1 in NL did not reach its potential, as illustrated by the follicle S:P ratio of 6.9:1 in the skin. This suggests an irreversible loss of cashmere fibres from the fleece following the cycle of brush end formation in February.The maximum mean length of cashmere and time of occurrence were similar in grazing and penned does, although grazing does were only sampled in 4 months of one year.

Epidermal growth factor: a critical factor in fetal maturation?

Epidermal growth factor (EGF) infused over 3-14 days into fetal sheep of 110-125 days gestation resulted in a number of morphological and endocrine changes. Striking hypertrophy of the skin, wool follicles and their accessory structures was seen, together with a reduction in the ratio of secondary to primary follicles and degenerative changes in wool fibres associated with shedding of fibres. Adrenal, thyroid, liver and kidney weights were increased while thymus weight was decreased. The increase in adrenal size resulted from cortical hypertrophy and was associated with increased cortisol secretion. Thyroid hypertrophy was accompanied by an increase in colloid stores, decreased plasma thyroxine and reverse triiodothyronine (T3) concentrations, unchanged plasma T3 and thyroid-binding globulin and raised thyrotropin (TSH) levels. Thyrotropin receptor affinity and content per gram of tissue were unchanged. Fetal and maternal plasma prolactin and growth hormone levels, and fetal plasma placental lactogen levels, were unchanged, although there was a significant rise in maternal plasma placental lactogen concentrations with high doses of EGF. Other maturational parameters such as switching from fetal to adult haemoglobin and liver glycogen content were unaffected.

Fibre shedding in relation to seasonal changes in day length and atmospheric temperature

Fibre shedding in relation to seasonal changes in day length and atmospheric temperature

The administration of flumethasone, by three different routes, its measurement in the plasma and some effects on wool growth in Merino wethers.

Flumethasone was given to Merino wethers weighing 30-50 kg at rates of 0.62-1.35 mg/kg(0.75) by intravenous (experiments 1 and 2), intraruminal (experiment 4) and subcutaneous (experiment 5) routes over 8 days. In experiment 3, 1.2 mg flumethasone/kg(0.75) was given intravenously over 4, 5 or 6 days. The plasma concentration profiles showed concentrations in the order: intravenous greater than subcutaneous greater than intraruminal. Plasma concentration patterns usually were highest during the first 48 h of infusion followed by relatively stable values. This last feature was not evident in experiments when the rate of hormone infusion was increased. Estimates of the metabolic clearance rates for flumethasone in experiments 1, 2 and 5 were 200-700 ml/min during the equilibrium concentration periods. The effects of flumethasone on some aspects of wool growth revealed interactions between the routes of administration, the period of dosage and the rate of wool growth in the recipients. In experiments 1 and 2 intravenous infusion of 1.20-1.33 mg flumethasone/kg(0.75) caused the shedding of all wool fibres about 30 days after treatment. Some effects of dosing sheep with flumethasone at a time when wool growth was decreasing were also observed in experiment 2. Flumethasone given at a rate of 1.2 mg/kg(0.75) over 4, 5 or 6 days caused the shedding of only some wool fibres which were firmly retained on the sheep by the continuous fibres. Intraruminal and subcutaneous infusions of 0.62-1.35 mg flumethasone/kg(0.75) had similar results to the last in the majority of animals although in a few cases no discontinuity of wool fibres was observed. Recovery in wool growth was observed after treatment. Animals regained their pretreatment wool growth in experiments 1, 4 and 5 by 60 days after treatment and probably equalled at that time wool growth in controls. Recovery was retarded in some individuals in experiment 2 and in some groups in experiment 3. In experiment 1, 21 days wool growth was estimated to have been lost. Some aspects of complete versus partial shedding of wool fibres are discussed particularly with reference to wool harvesting. Some similarities in the appearance of fleeces of steroid-treated sheep and naturally shedding animals are also discussed. In some experiments, particularly when the infusion rate of flumethasone was increased (experiment 3), the sheep showed temporary but significant feed refusals during, but more commonly after, treatment. Speculative discussion as to the metabolic causes of this response is included.

Development, structure and seasonal change in the fleeces of unimproved Scottish Blackface sheep from the Hebrides

SUMMARYDetails are given of the fleece and other characteristics of three rams and three ewes of a strain that has lived feral on the island of Boreray in the St Kilda group since 1930.The animals are horned and short-tailed, the rams are about 60 cm high at the withers and weigh about 45 kg at maturity, while the ewes weigh between 25 and 30 kg and are 55 cm high. The ewes reached their maximum weight after 1 year, but the rams increased in weight during the 3 years under observation.The fleeces were shorter and finer than those of the modern Blackface, tending to have kemps rather than hairy heterotype fibres. The fleece weight was 1·25 kg, staple length ranged from 75 to 150 mm and mean fibre diameters ranged from 23 to 32 μm.Variable fleece casting occurred although no more than about 80% of both the primary and secondary follicles became inactive during the winter. Unlike other primitive breeds studied there was a relatively narrow peak of follicle inactivity in midwinter, although in the ewes this tended to occur later in the winter, as observed in improved breeds.There was a subsidiary small peak of follicle inactivity in August corresponding to the primitive shedding of the summer coat. Maximum fibre medullation occurred in June, and there was a second smaller peak in September.As in other primitive breeds a relatively high proportion of follicles lacked fibres at birth, but this retardation of development was no longer evident by 14 days when the usual peak in medullation occurred. More fibre shedding was observed at 56 days than in the modern Blackface. The fibre type arrays were of Plateau P1 type.

Post-natal follicle development and fleece changes in two selection lines of Scottish Blackface sheep

SUMMARYFleece and skin samples were taken at intervals from birth to 86 days from Scottish Blackface lambs born into one line selected for hairiness, another for fineness and an unselected control line. The birthcoats in the Hairy line were longer than those in the Fine line, and had a predominance of Plateauo and Pi fibre type arrays, whereas P2 and P3 arrays predominated in the Fine line. The Hairy group had significantly more halo hairs and hairy-tip curly-tip fibres, but significantly fewer histerotrichs.Most secondary follicles had fibres by 56 days, and development appeared to be faster in the Control than in the other two groups. The Hairy and Control groups had consistently high percentages of primary medullation, whereas the Fine group had a peak at 14 days. The Fine group had consistently low secondary medullation, whereas it increased in the Hairy and Control lambs, apart from a set-back at 28 days.Up to 56 days the Fine group had no fibre shedding in the skin, and the Hairy group had most, although the incidence in any sample was less than 2%. There was more follicle inactivity at 86 days, and the Fine group then had most.

The effects of short-term undernutrition and adrenocortical stimulation on wool growth

SUMMARYSeven daily doses of 60 or 120 mg cortisol administered to mature sheep given a maintenance ration depressed wool fibre diameter by approximately 10%. Similar treatment with 120 mg cortisol for 14 days produced a more severe and prolonged effect, though fibre diameter was unaffected by a series of seven injections of 40 IU ACTH given every second day.Fourteen days at 10% of maintenance and 14 days' cortisol treatment were applied to mature sheep fed either continually at 150% maintenance, or at 75% followed by 150% maintenance. Cortisol treatment was associated with a significant reduction in fibre diameter only in the animals fed at 150% maintenance. Restriction to 10% maintenance for 14 days had no such effect. Approximately 20% of fibres were shed following cortisol treatment in both nutritional groups, but a marked ‘break’ in the fleece occurred only in the 75% maintenance group.A low plane of nutrition is confirmed as a major factor predisposing to ‘tenderness’ and ‘break’, and short-term adrenocortical stimulation is shown to be sufficient to produce the reduction in fibre diameter and increased fibre shedding associated with these faults. However, semi-starvation (represented by restriction to 10% of maintenance) appears to have played a relatively minor role in their development.

Casting of the fleece in sheep. Estimation of experimentally induced fibre shedding rate

SUMMARYA simple and rapid technique for estimating changes in fibre brush-end formation rate is described. The technique was used to give a quantitative estimate of the extent of brush-end formation induced by exogenous hormonal treatment of normal sheep and to establish the time relationship between treatment, fibre brush-end formation and the subsequent casting of the fleece.

Wool fibre shedding in some Merino sheep

Four sheep were investigated by monthly skin sampling for 3 years in Australia, and four sheep by quarterly sampling for 3 years in Scotland. Those in Australia had shedding in 30–50% of the samples while those in Scotland had shedding in only 15–30%, but in both the incidence of brush ends was less than 1%.

Effect of adverse nutrition on the skin and wool follicles in Merino sheep

The effect of adverse nutrition on the body weight, skin thickness, and wool follicles of five groups of five Merino wethers has been observed over a period of 64 months in an experiment on the utilization of low quality roughage. All animals on the poorest diet (roughage containing 2.6% crude protein, ad lib.) were transferred to a recovery ration of lucerne chaff, wheat, linseed meal, and meat meal (33 : 33 : 20 : 13) at 6–9 weeks after the commencement of the experiment. Only three animals on the better diets needed this recovery ration. In general, changes in skin thickness paralleled changes in body weight. A marked increase in skin thickness which followed shearing was probably due to cold stress. Fibre shedding was a major feature of the reaction of the follicle population to adverse nutrition, but all afflicted follicles regenerated their fibres when the recovery ration was given. Primary (P) and secondary (S) follicles responded differently to adverse nutrition. Approximately 20 000 P follicles and 155 000 S follicles were examined. 1.4% of the P follicles and 9.%% of the S follicles showed evidence of shedding.

Shedding of fibres in sheep

Shedding of fibres in sheep

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.

A comparative study of fleece growth in Tasmanian Fine Merino and Wiltshire Horn ewes

1. From repeated fibre samplings and several skin biopsies on six Tasmanian Fine Merinos and eight Wiltshire Horn adult ewes variations in fibre diameter, fibre growth rate, and fibre regeneration or shedding frequency were measured over a period of 15 months. Slight differences were present in the treatment of the two breeds, but from the combined evidence of the live weights and fibre diameters maintained, it was concluded that these were negligible, that both breeds were under closely comparable conditions, and that their performance was at a moderately high and typical level for each breed.2. In the Merinos fibre diameter (ca. 20 µ) fluctuated little during the period of observation, whereas in the Wiltshires it varied over a wide range from less than 40µ in winter to more than 80µ in summer. There were negligible differences between the three body regions, back, side, and belly, in the Merinos, but in the Wiltshires the belly grew markedly coarser fibres than the other two regions.3. The fibre growth rate in the Merinos did not vary greatly from 7 to 8 mm. per 28 days throughout the period of observation or between the body regions. In the Wiltshires, fibre growth rate showed extreme variations from a minimum of about 3 mm. during the winter to a maximum of about 12 mm. per 28 days at the end of summer, with significant differences between the three body regions. However, in spite of these differences in the mode of growth, the total length of fibre grown per annum at the midside was approximately the same (10 cm.). Thus, were it not for fibre shedding, the Wiltshire Horn breed would grow a short-wool fleece.

A STUDY OF THE COAT OF THE MOUFLON OVIS MUSIMON WITH SPECIAL REFERENCE TO SEASONAL CHANGE

Changes in the coat and skin of a mouflon sheep were followed from the age of three months to the age of twenty‐one months. The birth coat was shed between four and six months of age and there was a marked moult the following spring. During both these moults the coat was lost as a single mat. The wool of the under‐coat was shed only once during the spring moult, whereas the hairs of the outer coat were shed a second time in summer, but this was less obvious than the spring moult.Details of the histology of the skin and of fibre shedding are given in addition to incidental observations on growth and the horns.

Fibre medullation in Blackface lambs and hoggs

A method has been described of assessing the average degree of medullation in fleece samples. This method combines information about the various fibre types and the proportion of each present in the sample, by assigning 100 fibres to classes with scores 1–5 according to the degree of medullation. A weighted mean score was determined, ten times this mean being defined as the ‘medullation index’. The index has been used for 2 years on samples taken from 2-month-old lambs and 14-month-old hoggs of the Blackface breed. Drawings of fibre types showed that the internal and external diameters and their ratio all increase with the score.The mean medullation index for the 2-month-old lambs in the 2 years was 25·6 and 24·8. The effects of sex and type of birth of lamb and age of dam were assessed by fitting constants, but their contribution to the total variance was very small. The regression of medullation on age of lamb when sampled was −0·11 units per day in both years, and was highly significant. Possible explanations for this decline of medullation are discussed.The mean medullation index for 14-month-old hoggs was 16·1 in both years. Estimate of correlation between lamb and hogg for the 2 years were + 0·45 and + 0·33. It is probable that variation in medullation within the fleece and in fibre shedding account for these low values.

A survey of the follicle populations in a range of British breeds of sheep

Details are given of the S/P follicle ratios of a number of British breeds of sheep. These are discussed in relation to the figures of different authors for other breeds. Figures are given for the incidence of fibre shedding and follicle abnormalities, and evidence is presented which suggests that, at any rate in British breeds, follicles are formed after birth and it is suggested that the number formed may be roughly constant in all breeds. There is an appendix describing statistical treatment of the question of follicle competition.

Observations of nutritional and seasonal changes in the fleeces of some masham sheep

1. An experiment was carried out in summer when sheep do not normally shed their wool fibres to see if a poor diet would induce fibre shedding. Observations were then continued for a year to follow seasonal variations in the fleece.2. The two experimental sheep lost about a quarter of their body weight during the nutrition experiment. Measurement of areas tattooed in the skin showed that there was a reduction of about 5% in these areas.3. Histologieal observations of skin samples showed that there was very little fibre shedding during the nutrition experiment. This suggests that poor nutrition alone will not cause sheep to shed their fibres. More fibre shedding took place during the winter even though the sheep were well fed, suggesting a seasonal stimulus for shedding.4. ‘Brushes’ which are normally formed when fibres shed in primary follicles were also seen in secondary follicles.5. Observations were made during the nutrition experiment of the blood vessels in the skin and glycogen in the outer root sheaths of the follicles. No changes were seen in either the numbers of vessels, or the amount of glycogen present.6. The weight of wool produced per unit area per day was determined at each sampling time during the whole year. The experimental sheep behaved differently from the controls in their wool production during the nutrition experiment. Thereafter all sheep behaved the same, and seasonal fluctuations in wool production were found.7. The mean length and mean diameter of the wool produced was determined at each sampling time throughout the year.

Observations on Merino × Herdwick hybrid sheep with special reference to the fleece

1. Observations, mainly concerning the fleece and pigmentation, were made on about 80 F1 Merino × Herdwick sheep. Of these, nine were used for intensive fleece studies, and skin samples were obtained from six.2. Pigmentation in all the F1 lambs was greatly reduced as compared with the Herdwick breed, the majority being entirely white on the main fleece area, with varying amounts of black and brown speckling on the face, legs and neck. A few were entirely white, like the Merino. The shade of colour of the Herdwick dam did not affect the amount of pigment on her half-Merino offspring.3. The fibre type array most frequently encountered was one not previously described, which has been named Incline. Fine Plateau arrays were also frequent, especially on the mid-side and britch positions. Other arrays which occurred were Coarse Plain, Fine Plain, Ravine, and Coarse Plateau.4. The hogg fleece weights averaged approximately 4·5 lb. for females and 5 lb. for males, which is about double the average weight of Herdwick hogg fleeces. In general appearance they showed some superficial resemblance to Romney and Corriedale fleeces, but there was much variation between individuals. None closely resembled either parental fleece type, but the Merino influence was much more manifest than the Herdwick. Kemp, if present, was usually long and fine, resembling hair.5. Growth of the experimental animals was normal. In an endeavour to assess conformation, measurements were taken on a few sheep, and compared with similar measurements on Herdwick and Swaledale.6. The follicle population showed characteristics of both parental breeds, and varied greatly between individuals. The highest S/P ratio was 9·0, with a follicle density of 3000 per sq.cm. In comparison with the British breeds previously studied, autumn and winter fibre shedding was delayed and reduced in the crossbreds.7. Thetotal number offibresper tattooed square remained stable after sample 2 (about 2 months old). There was no significant difference between sheep or between samples in percentage of coarse, medium and fine fibres, but there was a highly significant difference between positions S (shoulder), A (last rib), B (britch) and D (rump). Mean fibre density was approximately 3000 per sq.cm., and mean fibre quality proportions (by number) in the A position was coarse 10%, medium 24% and fine 66%.8. Nearly 85% of the total clean weight of wool produced was grown in the late spring and summer months. The total wool grown was divided into three qualities and the proportion of the total weight derived from each quality was coarse 23·69%, medium 41·21%, and fine 35·10%. The distinction between the three qualities was often quite doubtful and never as clear as in the Herdwick breed. There were significant differences in proportions of coarse, medium and fine wool, between regions, between seasons and between sheep.9. In the discussion, which concludes the series of studies of fleece and follicle population, the following topics are treated: error of estimate of proportions in work of this kind; time of development of post-natal secondary follicle, and theories of the possible influence of primary follicles on the development of secondary follicles; post-natal growth in size of follicles in Merino and other breeds; autumn moult; recapitulation in follicles during regrowth after fibre shedding; significance of fibre type arrays; origin of the Longwool breeds; protective birth-coats; pigmentation; ‘lift’ in British wools; and the possibilities of establishing a breed with the Merino type of fleece on British hill and mountain farming areas.

The Shedding of Certain Fibres in the Goat of the Lamb

IN his letter1 in NATURE on Ovis astore, Prof. A. F. Barker discusses the shedding of certain fibres by domesticated sheep. As he points out, the shed fibres are usually regarded as representatives of the outer coat of wild sheep. The persistent fibres, of indeterminate growth, are looked upon as derivatives of the ancestral under-coat of wool. It is believed that the fibres of this under-coat, instead of ceasing to grow after a few weeks or months, and later being shed, have taken to maintaining their growth for a very much longer time, often probably throughout the natural lifetime of the animal.