Crimp Frequency Research Articles

Wool fibre crimp is determined by mitotic asymmetry and position of final keratinisation and not ortho- and para-cortical cell segmentation

Crimp, a distinguishing feature of sheep fibres, significantly affects wool value, processing and final fabric attributes. Several explanations for fibre bending have been proposed. Most concentrate on relative differences in the physicochemical properties of the cortical cells, which comprise the bulk of the fibre. However, the associations between cortical properties and fibre crimp are not consistent and may not reflect the underlying causation of fibre curvature (FC). We have formulated a mechanistic model in which fibre shape is dictated primarily by the degree of asymmetry in cell supply from the follicle bulb, and the point at which keratinisation is completed within the follicle. If this hypothesis is correct, one would anticipate that most variations in fibre crimp would be accounted for by quantitative differences in both the degree of mitotic asymmetry in follicle bulbs and the distance from the bulb to the point at which keratinisation is completed. To test this hypothesis, we took skin biopsies from Merino sheep from sites producing wool differing widely in fibre crimp frequency and FC. Mitotic asymmetry in follicle bulbs was measured using a DNA-labelling technique and the site of final keratinisation was defined by picric acid staining of the fibre. The proportion of para- to ortho-cortical cell area was determined in the cross-sections of fibres within biopsy samples. Mitotic asymmetry in the follicle bulb accounted for 0.64 (P < 0.0001) of the total variance in objectively measured FC, while the point of final keratinisation of the fibre accounted for an additional 0.05 (P < 0.05) of the variance. There was no association between ortho- to para-cortical cell ratio and FC. FC was positively associated with a subjective follicle curvature score (P < 0.01). We conclude that fibre crimp is caused predominantly by asymmetric cell division in follicles that are highly curved. Differential pressures exerted by the subsequent asymmetric cell supply and cell hardening in the lower follicle cause fibre bending. The extent of bending is then modulated by the point at which keratinisation is completed; later hardening means the fibre remains pliable for longer, thereby reducing the pressure differential and reducing fibre bending. This means that even highly asymmetric follicles may produce a straight fibre if keratinisation is sufficiently delayed, as is the case in deficiencies of zinc and copper, or when keratinisation is perturbed by transgenesis. The model presented here can account for the many variations in fibre shape found in mammals.

Genetic parameters for wool traits in Finnsheep lambs

Genetic parameters were estimated for wool characteristics of white and coloured Finnsheep. The data consisted of 5 309 lambs from ordinary production flocks, the Finnsheep nucleus flock and a breeding flock. The variance component estimation was done applying REML analyses. Wool traits included fleece uniformity, density, staple formation, lustre, crimp frequency, fineness grade and staple length. There was a smaller dataset that contained also lamb live weight, greasy fleece weight and additional fleece characteristics including fibre diameter measured with the OFDA method. The variance components for direct and maternal effects were estimated using bivariate analysis for 42-day, 120-day weight and greasy fleece weight. Heritability for visually assessed wool characteristics varied from 0.23 to 0.43 and for measured traits from 0.45 to 0.62. Staple length had a high negative genetic correlation with crimp frequency and fineness grade. Heritability of greasy fleece weight was high (0.55) and that of fibre diameter 0.62. The genetic correlation between crimp frequency and fibre diameter was negative (- 0.56). The results imply that the assessed traits are useful indicators for fleece quality and those of major importance can be introduced into the breeding programme. The results suggest that there is no antagonism in selection for both growth capacity and wool quantity.;

Implications to fleece evaluation derived from sources of variation contributing to cashmere fibre curvature

Cashmere fibre curvature (crimp) has important impact on the softness and quality of cashmere textiles, the efficiency of cashmere processing and cashmere production. This work was aimed to quantify the magnitude and direction of factors affecting cashmere fibre curvature, with data collected from 11 Australian commercial cashmere farms, using general linear model analysis. Nineteen parameters were recorded for 1244 goats. Following log transformation the best model for fibre curvature included farm, age, clean washing yield, mean fibre diameter, cashmere yield, fibre diameter standard deviation, and live weight and the interactions between these terms. The percentage variance accounted for was 71.7%. Mean fibre diameter alone accounted for 39% of the variation in fibre curvature and farm accounted for 49% of the variation. Cumulatively mean fibre diameter and farm accounted for 66.6% of the variation existing in fibre curvature. For the other terms, age added 2.2% and the other fibre measurements a further 2.9% to variation accounted for by the best model. Results suggest that within a farm, using cashmere fibre crimp frequency to estimate mean fibre diameter has a correlation of 0.72—provided the trained observers perform as well as the calibrated laboratory equipment. On the other hand, however, results indicate fibre curvature not to be a reasonable indicator of mean fibre diameter differences across farms. Farm-effects on fibre curvature are large and may explain the difficulties cashmere growers experience when they visit other farms to visually evaluate cashmere goats prior to purchase. This work indicated that heavier goats are likely to produce cashmere with a lower fibre curvature. As this relationship did not differ between farms, it is reasonable to conclude that all goats exhibit this phenotypic response. Using cashmere fibre curvature (crimp frequency) as a tool for changing mean fibre diameter or selecting homogenous batches of fibre for sale will be reasonably effective within a farm, but is not a reasonable indicator and predictor of mean fibre diameter differences between farms.

Frequency of shearing increases growth of fibre and changes objective and subjective attributes of Angora goat fleeces

SUMMARYThe impact of genotype and of frequency and timing of shearing, on mohair attributes and production of modern Angora goats was studied. Goats in the southern hemisphere grazed pastures between February 2004 and 2006. There were seven shearing treatments by three genetic strains with four or eight replicates of individual goats. Treatments were: three different 6-month shearing intervals and two of 12-month shearing intervals with different months of shearing, a 7-month winter shearing interval and a 3-month shearing interval. Genetic strain was based on sire line: 1·0 South African; 1·0 Texan; and Mixed 0·5 South African and 0·5 Texan. Annual greasy mohair production was 5·08 kg, and average clean fleece production was 4·37 kg. The Angora goats produced an annual clean fleece equivalent to 0·122 of their mean fleece-free live weight which was equal to 0·34 g/kg/day. Measurements were analysed over the period of spring 2004 shearing to spring 2005 shearing, excluding the June–December shearing treatment. Increased frequency of shearing increased fleece growth and affected 13 objective and subjective attributes of mohair that were evaluated including clean washing yield, fibre diameter and fibre diameter variation, incidence of medullated fibres, staple length, fibre curvature, crimp frequency, style, staple definition, staple fibre entanglement and staple tip shape. The direction of these effects were generally favourable and for most attributes the magnitude of the response was linear and commercially important. Each additional shearing resulted in an additional 149 g of clean mohair representing 0·034 of the annual clean mohair production. This increase was associated with a 0·6 cm increase in staple length and 0·32 μm increase in mean fibre diameter. In conclusion, Angora goats shorn less frequently grew less mohair that was more likely to be entangled in spring. Managers of Angora goats should take note of these findings.

A Quantitative Study of the Microstructure and Biochemistry of the Medial Meniscal Horn Attachments

Little quantitative data is available on the structure of meniscal attachments. Therefore, as an aid to designing meniscal replacements as well as a possible explanation for mechanical behavior, this study was designed to further the knowledge of the microstructure and biochemistry of native meniscal attachments. Bovine medial meniscal attachments (the external ligamentous portion as well as the transition zones at the bony insertion) were removed and prepared for microstructural evaluation. After embedding in paraffin, the samples were sliced on a microtome and stained for quantitative analysis. The anterior and posterior insertion sites are known to contain three zones: subchondral bone, calcified fibrocartilage, and uncalcified fibrocartilage. Additionally, others have shown that the anterior insertion site contains a ligamentous zone. The insertion zones were further divided into proximal, middle, and distal zones. The posterior attachment's insertion site had a significantly greater thickness of interdigitations, subchondral bone, uncalcified fibrocartilage, and calcified fibrocartilage zone thickness compared to the anterior attachment insertion. The anterior attachment's insertion had the greatest GAG fraction in each zone when compared to the posterior attachment's insertion. GAG fraction decreased from the meniscus to the subchondral bone. Both GAG fraction and normalized thickness varied within a given zone, decreasing from the distal to proximal regions in both the anterior and posterior attachments' insertion zones. Crimp frequency of the collagen fibrils in the external ligamentous portion of the tissue was homogeneous along the length. The findings from this study agree with previously published material property data on the medial meniscal attachments, and could be used in the future to design methods of attachment for tissue engineered replacement menisci.

Influence of nutrition, fibre diameter and fibre length on the fibre curvature of cashmere

Raw and dehaired Australian and Chinese Liaoning cashmere were evaluated for cashmere fibre curvature, cashmere fibre length, resistance to compression, and mean fibre diameter. Tested cashmere originated from commercial lots, and previous experimental samples. In Australian goats, cashmere fibre curvature was dependent on nutrition. Goats fed to lose weight grew cashmere with significantly (P&lt;0.05) increased fibre curvature compared with goats fed to gain weight (61 v. 47°/mm) but total fibre curvature (fibre curvature × fibre length) was not affected by nutrition treatment. In raw Liaoning cashmere, there was a significant (P&lt;0.001) difference between each age and sex group in fibre curvature (bucks 52; does 65; kid bucks 78°/mm). Increasing Liaoning cashmere staple crimp frequency by 1/cm was correlated with an increase in fibre curvature of 6.5°/mm (r2 = 0.61). In raw and dehaired Australian and Liaoning cashmere, increasing mean fibre diameter and cashmere fibre length was associated with decreasing fibre curvature (for each 3 μm increase in mean fibre diameter fibre curvature declined 10–41°/mm; for each 10 mm increase in cashmere fibre length fibre curvature declined 3–13°/mm). Increasing cashmere mean fibre diameter was positively correlated with dehaired cashmere fibre length (for each 3 μm change in mean fibre diameter there was a change of 7–23 mm in length). In Australian and Liaoning cashmere, the direction of responses to changes in cashmere fibre attributes measured on the fibre curvature was similar. In raw Australian and Liaoning cashmere, increasing the ratio of cashmere fibre length:mean fibre diameter was associated with reduced fibre curvature. It was concluded that the high fibre curvature of Liaoning cashmere may be a consequence of low mean fibre diameter and short fibre length resulting from a production system where goats are relatively poorly fed. The results suggest that for Australian cashmere, only a certain number of crimps are produced. As such, crimp frequency in Australian cashmere is time dependent and not length dependent. Producers can manipulate the fibre curvature attributes of their cashmere by altering cashmere production via nutrition management. Preparation and testing procedures for the selling of raw cashmere and definitions of cashmere may need to be revised to include fibre curvature.

Merino sheep responses to different stocking rates and seasonal variation under rangeland conditions of Lesotho

Merino sheep responses to stocking rates were determined over a one-year period. The experimental design consisted of three stocking rates; light (2.0ha LSU-1), moderate (1.25ha LSU-1) and heavy (0.5ha LSU-1) in a Randomised Complete Block Design with three replicates per treatment. Data collected were live weight, grease fleece weight, staple length, fibre diameter and crimp frequency from ewes, and birth weight, growth rate, weaning weight and percent mortality from lambs. Ewes in the heavy stocking rate had significantly (P<0.05) lower final weight, grease fleece weight and fleece length than those in moderate and light stocking rates. Lambs in the heavy stocking rate had significantly (P<0.05) lower birth weight and weaning weight, but higher mortality than those in moderate and light stocking rates. It is concluded that heavy stocking rate significantly reduced ewe and lamb performances.

Pedigree analysis of selected lines of Merino sheep. 1. Inbreeding

Four pairs of selection lines of Merino sheep consisting of 100 ewes and 5 rams were established at the Trangie Agricultural Research Centre in 1951. Each line was selected (mass selection) for the appropriate character and direction (Plus or Minus) for a period of 18 years (5 generations). The characters subjected to selection were clean fleece weight, crimp frequency, weaning weight, and skin folds. The average inbreeding coefficients calculated from the pedigree data of the those selected lines ranged from 3.79% in the Fleece Plus line to 9.09% in the Folds Plus line, corresponding to average annual inbreeding rates of 0.211% and 0.505%, respectively. Generally, there were similar fluctuating patterns in the means of inbreeding coefficients across years, with higher variation in the early years, and different rates of inbreeding in different flocks. The only exception was the Fleece Plus flock with a trend to increased variation across years, higher fluctuations in average inbreeding coefficient in final years, and inbreeding, which was not located in the 95% confidence interval of the inbreeding in flocks simulated for an infinitesimal model. Although the Folds Plus line showed inbreeding within the 95% confidence interval of simulation inbreeding, it was located at the higher end of the confidence interval, due to natural selection. Excellent agreement was found between the simulated flocks inbreeding (6.54%) and predicted inbreeding from an adaptation of the formula of JA Woolliams, NR Wray, and R Thompson (1993) (6.44%).

Intake and long-term cysteine supplementation change wool characteristics of Romney sheep

Sulfur amino acid supplementation increases wool production in sheep at low planes of nutrition but it is unclear whether there is any benefit of supplementation at planes of nutrition above maintenance and what implications this might have for wool quality characteristics. This experiment directly investigated the interaction between sulfur supplementation and plane of nutrition in terms of wool growth and fibre characteristics. Twenty-four Romney ewes, acclimatised in individual metabolism units over a 7-week pre-treatment period, were allocated to 1 of 4 treatment groups based on a 22 factorial arrangement. Groups were low (L) or high (H) intake (0.8 or 1.3 maintenance, respectively) with continuous intravenous infusion of either saline (–Cys) or cysteine (+Cys, 2 g/day). During the 3-month treatment period, measurements were obtained for liveweight, plasma cysteine concentration, wool sulfur concentration and output, clean wool growth, mean fibre diameter (MFD), length growth rate (LGR), colour, loose wool bulk, handle, and crimp frequency and character. Clean wool growth response (P &lt; 0.05) to cysteine supplementation was greater for the L sheep (6.06 v. 4.31 g/100 cm2) than the H sheep (7.20 v. 6.13 g/100 cm2). The response to supplementation in LGR (P &lt; 0.01) was similar in both H (14%) and L (20%) sheep. There was no response in MFD due to sulfur supplementation, although fibre diameter measurements made along the fibres suggest that there was a response in L but not H sheep (P &lt; 0.1). Wool sulfur concentration and output increased as a result of cysteine supplementation but concentration increased more in L (30.6 v. 24.5 mg S/g; P &lt; 0.01) than in H sheep (28.4 v. 26.2 mg S/g). Qualitative electrophoresis analyses suggested that the increase in wool sulfur was achieved primarily by an increase in ultra-high-sulfur proteins. Crimp frequency and character were both significantly (P &lt; 0.01) enhanced by cysteine supplementation. It is concluded that cysteine supplementation, at feed intakes that commonly occur in the commercial situation, can produce a useful increase in wool growth. This growth increase is primarily accomplished by increasing length growth rate rather than fibre diameter, which should also improve the value of the wool fibre produced.

Application of proteomics for determining protein markers for wool quality traits.

The technique of two-dimensional electrophoresis (2-DE) has been under investigation for its usefulness in identifying protein markers for wool quality traits in sheep. However, before this could be achieved, unique problems relating to the detection and quantitation of wool proteins needed to be overcome so that 2-DE protein maps could be examined using computational programs like Melanie II. Four protein staining regimes were examined. Colloidal Coomassie Blue G-250 was found to be superior to Coomassie Blue R-250 and gave satisfactory staining of all protein classes. Silver staining detects minor strings of keratinous proteins, but unfortunately it negatively stains intermediate filament proteins, the major high sulphur proteins (HSPs) and the high glycine tyrosine proteins and the latter two classes can only be seen by overstaining the background of the gel. In contrast, labeling reduced keratins with [14C]iodoacetamide, followed by autoradiography detection, results in a protein map with low background and all protein spots stained positively. 2-DE has been used to obtain wool protein maps of Lincoln/Merino chimeric sheep to examine wool originating from two genotypes grown with different crimp frequencies within the same fleece. Between fleece, variations have also been examined. Work to date suggests that several major HSPs may be associated with the fibre curvature trait known as crimp frequency. From matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectral mapping, one of these proteins has been identified as being from the B2A family from the HSP class.

Response to selection for ultrafine Merino sheep in New Zealand: I. Wool production and wool characteristics of ultrafine fibre diameter selected and control Merino yearlings

Merino ewes were screened for low fibre diameter from 15 000 yearlings within 12 flocks to establish a foundation flock in 1987, which was expanded to 500 ewes over the subsequent two years. Ewes were selected on fibre diameter BLUP breeding values. For comparison, a control flock of 100 ewes was randomly selected from the same sources. Data from approximately 2000 progeny over five birth years within 70 sire groups were analysed. Traits measured were live weight, greasy and clean fleece weight, yield, mean fibre diameter (FD), staple length, staple strength, staple crimp frequency, resistance to compression, Commission International de l'Eclairange (CIE) tristimulus value for scoured wool and coefficient of variation in fibre diameter. The ultrafine progeny had 2-μm finer FD, 0.6 units less yellow and had 0.6 more crimps/cm (all P<0.001) than their control counterparts. This experiment suggests that formation of an open nucleus breeding population by intensive screening for fibre diameter from a commercial population will improve selection response relative to traditional within flock selection without screening or to screening rams only.

Case control study of diarrhoea and faecal soiling in two to six-month-old lambs

A case control study was nested within a longitudinal study of faecal soiling on eight commercial farms in the south west of England. Eighty-two incident cases of faecal soiling in...

Physical Properties and Processing of Fine Merino Lamb's Wool

The fiber properties and handle of fine Merino lamb's and fleece wool are critically reviewed in Part 1 of this series of papers. Those objective characteristics that distin guish these two classes of raw wool and appear to account for the relative softness of hand of lamb's compared with fleece wool are presented here. The best single parameter indicating softness is resistance to compression. A reduction in staple crimp frequency or mean fibre diameter or both lowers resistance to compression and increases softness. The lower mean staple crimp frequency observed in wool grown in the first four months of a lamb's life is a visual indication of tactile softness compared with that of wool grown subsequently.

Physical Properties and Processing of Fine Merino Lamb's Wool

Literature pertinent to fiber properties and handle of fine Merino lamb's and fleece wool is critically discussed. The softness of handle of fine Merino wool varies inversely with loose fiber resistance to compression. This complex raw wool parameter has geo metric and mechanical attributes. Fiber bending and torsional rigidity are important mechanical factors that depend on mean fiber diameter, cross-sectional shape, and Young's modulus. Crimp frequency, amplitude, and form are equally important geo metric factors. Those characteristics that distinguish lamb's and adult wool and appear to account for the relative softness of hand of lamb's compared with fleece wool are presented in Part II.

A case control study of blowfly strike in lambs.

A case control study of the risk factors associated with blowfly strike was conducted on 11 farms in the south west of England. For each case, three control lambs were randomly selected from the remainder of the flock. Samples of blood, faeces and wool were taken from the cases and controls, and measurements of weight, dag score (faecal soiling), fleece length, crimp frequency and tail length were made. Conditional logistic regression was used to examine the univariate and multivariate relationships between the independent variables and the rate of blowfly strike. Case lambs had significantly higher dag scores and lower crimp frequencies than their matched controls, although the association with crimp frequency was confounded by dag score. The relationship between blowfly strike and fleece length was also strongly confounded by dag score. After stratifying by dag score, case lambs had shorter fleeces than their controls. Lambs with blowfly strike had significantly higher levels of blood copper and significantly lower levels of blood urea.

Fleece rot and body strike in Merino sheep. VI. Experimental evaluation of some physical fleece and body characteristics as indirect selection criteria for fleece rot

Indicators of staple thickness, staple weight, staple density, wool weight cm -2, crimp frequency, dust penetration, fibre diameter (mean, variability), birthcoat score, and neck and body wrinkle were evaluated for their suitability as indirect selection criteria against fleece rot and body strike. The fleece traits were assessed in 949 Merino ewe hoggets representing the progeny from 134 sires in 15 contemporarily managed flocks. Fleece rot and body strike were assessed following experimental induction. In decreasing order of importance, variability (s.d.) in fibre diameter, average staple thickness, crimp frequency, variability (c.v.) in fibre diameter, mean fibre diameter, birthcoat score, staple density, variability in staple thickness, staple weight, and neck wrinkle score, accounted for a significant component of the variation in liability of sheep to fleece rot. Body wrinkle, variability (c.v.) in staple thickness, staple length, dust penetration, and wool weight cm-2 were not important. Based on combined estimates of the heritability of the indicator trait and its genetic correlation with fleece rot, variability in fibre diameter (s.d.) and birthcoat score showed the highest potential as indirect selection criteria. Variability in fibre diameter (s.d.) also showed a similar scope for selection against body strike. Indicators of mean staple thickness, crimp frequency, dust penetration and wrinkle score showed little or no scope for indirect selection against fleece rot or body strike. The role of variability in fibre diameter (s.d.) as an indirect selection criterion for fleece rot and body strike in designed breeding programmes which include other important objectives, will need to be further evaluated, given an undesirable genetic correlation with clean fleece weight. High between-flock correlations were observed for a number of fleece traits and susceptibility to fleece rot. Susceptible flocks were characterized by fleeces with longer, heavier, thicker staples with a lower crimp frequency, and higher fibre diameter with a higher variability. Predicting the susceptibility of flocks to fleece rot and body strike, through a between flock index based on the measurement of simple fleece traits, is suggested.

Evidence of a unique developmental mechanism specifying both wool follicle density and fibre size in sheep selected for single skin and fleece characters.

Skin and fleece traits have been characterized in four lines of Merino sheep selected for high- and low-fibre diameter (D +/-) and staple length (L +/-) from a medium-woolled flock. Over a period of 20 years, each line responded in the desired direction, producing fleeces composed of thick or thin fibres and long or short wool staples. However, variations in the amounts of wool grown that might be expected from these procedures were compensated by changes in unselected characters. Thus a predicted difference in fleece weights between high and low staple length lines was reduced by an increase in fibre crimp frequency in L- sheep. Similarly, changes induced in fibre diameter in the D lines resulted in small effects on fleece weight in comparison to the large (and inverse) effects on follicle numbers. Towards the end of the selection regime, mean follicle density in D- sheep was twice that of D+ sheep. This intriguing response within the follicle population was examined further: an analysis of the relationship between follicle density and fibre diameter amongst the four lines revealed a highly significant, negative linear correlation. The implication of this statistical association is that the numbers of follicles initiated in skin during foetal life had a direct bearing on the sizes of wool fibres eventually produced. It was concluded that both features must be under the control of a single developmental mechanism. Since the expression of each of the characters is separated in time, the mechanism must be activated during the earlier event, i.e. at or before the phase of follicle initiation.

Selection responses in New Zealand Romney sheep

Data from a flock selected for high yearling greasy fleece weight and a randomly selected control group, derived from the same base flock, were analysed. Each flock contained 70-80 mixed-age breeding ewes mated to 4 rams each year. Data from yearlings born in the flocks from 1956 to 1979 were analysed. On average, they represented 8.5 generations. The accumulated selection differential in the selection flock was about 5 kg, and this resulted in a genetic response to selection of 0.7-0.8 kg in yearling greasy fleece weight. Estimates of the realised heritability of greasy fleece weight ranged from O. 10 to 0.17. Several significant correlated responses occurred in the yearling data. Relative to control flock means: clean fleece weight, staple length, mean fibre diameter, clean scoured yield, weaning weight, and liveweight increased; whereas quality number and crimp frequency decreased. Mean date-of-birth became earlier. Lifetime averages of the performance of ewes born between 1956 and 1971 indica...

Effects of Phenylalanine and Analogues of Methionine and Phenylalanine on the Composition of Wool and Mouse Hair

Administration of the methionine analogue methoxinine (O-methyl-DL-homoserine) to sheep substantially changed the composition of wool; in addition wool fibres were weakened and the staple crimp frequency was reduced for a prolonged period. The proportions of high-tyrosine proteins were reduced by 40-45% whereas the high-sulfur proteins were usually slightly increased. The content of high-tyrosine proteins in wool was still depressed in most sheep 70 days after dosing with methoxinine. These experiments supported a previous finding that the cystine content of wool and its crimp frequency are not causally related. Ethionine, another methionine analogue, did not consistently change the composition of wool. In some sheep there was no change in the proportions of high-tyrosine proteins following administration of ethionine, even though weak wool was produced. This result, together with the lack of association between the content of high-tyrosine proteins and the strength of wool fibres in a sheep given methoxinine plus methionine, indicates that a reduction of the high-tyrosine proteins is not a prerequisite for the production of weak wool. Neither a threefold increase in the phenylalanine intake by mice nor the administration of three analogues of phenylalanine (4-fluoro-DL-phenylalanine, 4-chloro-DL-phenylalanine and beta-(2-thienyl)-DL-alanine) to sheep altered the composition of hair or wool. Fluorophenylalanine was incorporated into all the constituent proteins of wool to the extent of c. 2% of phenylalanine residues. The other analogues studied could not be detected in wool.

Influence of Nutrition on Some Properties of High- and Low-Crimp Merino Wools and Their Cellular Components

High- and low-crimp wool fibers, due to the influence of low nutrition levels, had increased crimp frequencies and increased volume swelling in formic acid but decreased sulfur content and fiber diameter. Ortho- and paracortical cells were liberated by ultrasonification of the two types of wool swollen in formic acid. Low-crimp fibers disintegrate more readily than high-crimp fibers, and the rate is markedly accelerated in wools from sheep with low levels of nutrition. The expected compositional variations between ortho- and paracortical cells were observed, but in addition, both cell types were sensitive to genetic and nutritional variation.