Crimp Frequency Research Articles

The effects of anthelmintic treatment and season on the quantity and quality of wool grown by Merino sheep

Groups of 30 Merino weaner sheep were grazed in East Gippsland, Vic., and subjected to one of four anthelmintic programs during the 12-month period from December 1977. They were treated with thiabendazole either weekly (W), nine times (H), three times (L) or once (S). These programs resulted in marked differences in the degree of parasitism between the groups. Over the 12 months, parasites had no significant effect on yield, staple length or crimp frequency. However, compared with the wool from sheep treated weekly, greasy wool production was depressed by 13, 22 and 20% respectively in sheep given nine, three or one anthelmintic dose. Fibre diameter was also reduced. Dyebands were used to delineate wool grown during summer, autumn, winter and spring. Where parasite burdens were minimized (W group), wool growth, fibre diameter and rate of staple growth increased each season throughout the year. There was little increase in these characters in the other three groups until the spring, and wool growth and fibre diameter were significantly less than that of the W sheep in all but the initial summer season. Wool growth:fibre volume ratios indicated that sheep continued to initiate new fibres at least until the end of summer, when they were 9 months old. The subsequent depression in the wool growth of sheep dosed at less than weekly intervals provides further evidence of the deleterious effects parasites may have on the production of young sheep, even where anthelmintic is administered fairly frequently.

Dynamic mechanical analysis and image analysis characterization of crimped yarns

AbstractThe Quantimet image analysis system and dynamic mechanical analysis have been applied to characterization of crimped yarns. The image analysis system is useful for obtaining accurate measurements of crimps per inch, uncrimped versus crimped length, crimp wavelength, and crimp amplitude. In addition, the dynamic tensile mechanical properties of fibers and the dynamic compression mechanical properties of the fiber masses were examined. These analyses identify the relationships between crimp parameters and loss tangents for the first time. The loss tangents of fiber masses increase with increasing crimp frequency. The higher loss tangents of crimped yarns in the glassy region quantify both the internal friction of constituent fibers and the external fiber to fiber friction separately.

Influences of Fiber Geometry on the Performance of Nonwoven Air Filters

The effect, of fiber diameter and crimp frequency on the filtration performance of nonwoven fabrics were examined empirically. It was found that if fabric weight and density are kept constant, air permeability varies linearly with fiber diameter. When filtering a very dilute aerosol of submicron particles, the capture efficiency varies linearly with ln d s, where d is the effective particle diameter (taking Brownian motion into account) and s is the interfiber spacing. When a concentrated aerosol is filtered, penetration and specific cake resistance tend to limiting values as the fiber diameter approaches zero. As fiber crimp frequency is varied from zero, Frazier air permeability increases, but capture efficiency and specific cake resistance are affected only by a change from zero to a finite crimp frequency.

Fiber Crimp Characterization by Image Analysis

A method for rapidly and quantitatively measuring the two-dimensional crimp geometry of fibers using commercially available automatic Image Analysis instrumentation is described. The crimp frequency of a filament deknitted from a fabric is shown to be a useful indicator of fabric bulk. A macroscope device and a scheme for the measurement of three-dimensional geometry of crimp are outlined.

Response to selection in Australian Merino sheep. VIII.* Further results on selection for high clean wool weight with attention to quality

Results of selection for high clean wool weight per head with control of quality are reported for two selection groups over the period 1966–74. Results for the same experiment for the periods 1950–1959 and 1961–64 were reported earlier. Both groups were selected for high clean wool weight, one (S) with a ceiling on fibre diameter and degree of skin wrinkle, and the other (MS) with a lower limit on staple crimp frequency and a ceiling on skin wrinkle. Genetic progress in clean wool weight was greater in S than in MS over the 1966–74 period (0.12–0.15 lb/annum, compared with 0.06–0.09). This was to be expected from genetic correlations of clean wool weight with fibre diameter (low positive) and staple crimp frequency (high negative). The result supports the previous recommendation that staple crimp frequency is an inefficient way of controlling wool quality while attempting to improve quantity by selection, because its use severely restricts the likely progress in quantity. The actual rate of progress in the S group was similar to that in the period 1950–59, which was followed by a fall in superiority of the selected over the control group animals born during 1961–64. The recovery of response in the 1966–74 period negates the suggestion that the loss of response during the 1961-64 period was due to a 'plateau'. The most likely explanation is that a genotype x environment interaction occurred, such that the genetic gain made in the 1950-59 period could not be expressed in the poorer environments of 1960–65, but reappeared gradually under the improving environment of the 1966–74 period. Attempts to remove this interaction by regression of response on the mean clean wool weight of the unselected control group (as an index of the level of the environment) for each year, were not successful. The interaction is, therefore, not simply a case of all selection groups being equal when the environment is poor. ________________ *Part VII, Aust. J. Agric. Res., 26: 937 (1975).

Corrigendum - Relative efficiency of Merino and Border Leicester × Merino ewes

Thirteen South Australian strong-wool Merino ewes and eight Border Leicester × Merino ewes mated to Poll Dorset rams were fed on lucerne pellets ad libitum during late pregnancy and lactation in pens. Each of their single-born progeny was slaughtered at 33 kg full liveweight. Breeds were compared for efficiency of the ewe (organic matter intake per unit liveweight and clean wool per unit intake), efficiency of the lamb (liveweight and body solids gain per litre of milk), and efficiency of the ewe-lamb unit (liveweight and carcass weight per unit intake). Border Leicester × Merino ewes ate 7% less organic matter per unit liveweight than Merino ewes during lactation; however, there was no significant difference during late pregnancy. In terms of absolute intake 120 Merinos = 100 Border Leicester × Merinos. Border Leicester × Merino ewes were 73% as efficient in converting feed to clean wool as Merino ewes. Merino ewes grew wool of smaller diameter and higher crimp frequency than crossbreds. Lambs from the Merino ewes were as efficient in converting milk into animal tissue as the progeny from Border Leicester x Merino ewes during the first 4 weeks of suckling. Lambs from Merino ewes required on average 25 extra days to grow to the same slaughter weight and ate 110% more organic matter from solid feed than lambs from crossbred ewes. However, the proportion of feed eaten by the lamb was small (10%) compared with that eaten by the ewe. Lambs from crossbred ewes were 23% heavier than those from Merino ewes at the same age. The crossbred ewe-lamb unit, however, consumed 20% more feed and hence was as efficient as the Merino ewe–lamb unit. The Merino ewe–lamb unit was more efficient than the crossbred ewe-lamb unit when the lamb genotypes were slaughtered at the same liveweight (P < 0.05); however, the difference was not significant when expressed as carcass weight per unit intake.

Relative efficiency of Merino and Border Leicester × Merino ewes

Thirteen South Australian strong-wool Merino ewes and eight Border Leicester × Merino ewes mated to Poll Dorset rams were fed on lucerne pellets ad libitum during late pregnancy and lactation in pens. Each of their single-born progeny was slaughtered at 33 kg full liveweight. Breeds were compared for efficiency of the ewe (organic matter intake per unit liveweight and clean wool per unit intake), efficiency of the lamb (liveweight and body solids gain per litre of milk), and efficiency of the ewe-lamb unit (liveweight and carcass weight per unit intake). Border Leicester × Merino ewes ate 7% less organic matter per unit liveweight than Merino ewes during lactation; however, there was no significant difference during late pregnancy. In terms of absolute intake 120 Merinos = 100 Border Leicester × Merinos. Border Leicester × Merino ewes were 73% as efficient in converting feed to clean wool as Merino ewes. Merino ewes grew wool of smaller diameter and higher crimp frequency than crossbreds. Lambs from the Merino ewes were as efficient in converting milk into animal tissue as the progeny from Border Leicester x Merino ewes during the first 4 weeks of suckling. Lambs from Merino ewes required on average 25 extra days to grow to the same slaughter weight and ate 110% more organic matter from solid feed than lambs from crossbred ewes. However, the proportion of feed eaten by the lamb was small (10%) compared with that eaten by the ewe. Lambs from crossbred ewes were 23% heavier than those from Merino ewes at the same age. The crossbred ewe-lamb unit, however, consumed 20% more feed and hence was as efficient as the Merino ewe–lamb unit. The Merino ewe–lamb unit was more efficient than the crossbred ewe-lamb unit when the lamb genotypes were slaughtered at the same liveweight (P < 0.05); however, the difference was not significant when expressed as carcass weight per unit intake.

Effect of stocking rate on fleece measurements and their relationships in merino sheep

The wool characteristics of Merino wethers were measured for 6 years in a stocking rate experiment. The decline in fleece weight due to increasing stocking rate from 4.9 to 12.4 sheep per hectare was usually accompanied by a reduction in fibre diameter and staple length and an increase in staple crimp frequency. The magnitude of these responses differed considerably between years; in one year clean fleece weight was reduced by 50%, with an associated reduction of 5 µm in mean fibre diameter and one of 2 cm in staple length. In four of the six years of the experiment, variation in fibre diameter accounted for at least 50% of the variation in wool production between stocking rate treatments. The relationships between clean fleece weight and fibre diameter were similar between years, mean fibre diameter being reduced by about 1.8 �m for each kilogram reduction in clean fleece weight. Fibre diameter is the major determinant of wool price, and this information should improve the prediction of economic responses to changes in stocking rate.

3—THE TREATMENT OF WOOL IN LIQUID AMMONIA

The general effects of liquid ammonia on different wool qualities are described, and it is demonstrated that fine fibres are more affected by the reagent than coarse fibres. Differential contraction of the cortical components in the fibre as it supercontracts results in an increased crimp frequency, and this in turn is responsible for large increases in the observed bulk compressibility of the fibre assembly. Stress-strain data for untreated and ammonia-treated fibres are presented, and differences are explained in terms of morphological structure.

The appraisal of fineness in greasy wool sale lots

SUMMARYRelationships among quality number, crimp frequency and. fibre diameter of sale lots are reported for a wide range of Australian wools, the quality number appraisals being those of the selling broker and the successful bidder at auction.Results show that sale lots classified as having the same quality number exhibit a 95% confidence interval of ± 2·5 μm about the mean value. This variation is attributed first to the dependence of quality number on staple crimp frequency and secondly to the strength of the relationship between crimp frequency and fibre diameter.

Response to selection in Australian Merino sheep. VI. Inheritance of abnormal staple crimp; estimates of phenotypic and genetic parameters

The heritability of abnormal crimp in wool at various ages and the genetic and phenotypic cotreiations of crimp abnormality with several wool and body characters were estimated for Peppin Merino sheep. When examined by half-sib analyses of variance, the heritability of abnormal crimp scored at ages less than 4.5 years was low, whereas abnormality at 5.5 years and older was highly inherited. Heritabilities estimated by intra-sire dam-daughter regression analyses with fewer degrees of freedom did not show such a clear-cut pattern, although the estimates tended to increase with age. The genetic correlations of crimp abnormality scores at ages up to 4.5 years with scores at older ages were mainly low. Crimp abnormality scores at most ages had genetic correlations with wool and body characters at 15–16 months of age as follows: strong positive with fibre diameter, weak positive with greasy and clean wool weight, wrinkle score and staple length, and weak negative with fibre number. Genetic correlations with body weight, percentage clean yield, face cover score and crimp frequency were inconsistent. The phenotypic variance of crimp abnormality increased with age, owing almost entirely to an increase in the additive genetic variance. The environmental variance was approximately the same at all ages. Phenotypic correlations among crimp abnormality scores were generally higher between scores at close ages, and particularly at older ages. Crimp abnormality scores at all ages had positive phenotypic correlations with fibre diameter and wrinkle score and negative correlations with fibre number per unit area of skin and percentage clean yield.Crimp abnormality at old ages also had positive phenotypic correlations with greasy and clean wool weights. Environmental correlations of crimp abnormality with greasy wool weight, clean wool weight body weight and fibre number per unit area of skin were negative, and those with percentage clean yield and fibre number positive. Predicted correlated responses in crimp abnormality differed in some respects from correlated responses observed previously in groups of Peppin Merino sheep selected for high and low values of percentage clean yield, clean wool weight, fibre number per unit area of skin and fibre diameter. Methods of selection of sheep which would be expected to reduce crimp abnormality are outlined.

Response to selection in Australian Merino sheep. VII. Phenotypic and genetic parameters for some wool follicle characteristics and their correlation with wool and body traits

Four numerical characteristics-follicle depth, follicle curvature, number of follicles per unit area of skin, and ratio of number of secondary to number of primary follicles-describing the size, shape, and arrangement of wool follicles have been measured in Peppin Merino sheep at 4-5 months (weaning), 15-16 months (two-tooth shearing) and at later ages ranging from 2 1/2 to 7 1/2 years. Estimates of their repeatability, heritability and phenotypic, genetic, and environmental correlations with 10 wool and body characteristics are reported. All four follicle characteristics were found to be highly inherited and sufficiently correlated with wool characteristics to be of interest to both the wool biologist and the sheep breeder. Fixed environmental effects influenced the expression of some follicle characteristics, while others, notably follicle curvature at any age, were unaffected, and therefore potentially more useful as practical selection aids. Groups of sheep selected for clean wool weight with control of (i) fibre diameter and wrinkle score, and (li) crimp frequency and wrinkle score, exhibited changes in the four follicle characteristics, which agreed with what the genetic correlation estimates would predict. The role of follicle characteristics in the biology of genetic control of wool growth is portrayed by fitting causal models invoking follicle characteristics as intermediates between the gene and the wool character. The analysis separates three independent genetic control systems, the identity of which corresponds closely to factors postulated in previous theoretical studies.

Influence of nutrition on the crimping rate of wool and the type and proportion of constituent proteins.

When the nutritional level of sheep is restricted, the staple crimp frequency of the resultant fleece increases substantially whereas the cystine and high-sulphur protein contents decrease. This is in marked contrast to the direct relationship between crimp frequency and cystine content among sheep. These observations can be reconciled by assuming that variations in crimp frequency are attributable solely to a combination of follicle shape and fibre length growth rate without recourse to the more generally accepted theories relating to the proportion and distribution of ortho- and paracortical cells in the firbre cortex. The major portion of the decrease in the cystine content of high-crimp wools is due to the decreased synthesis of a specific protein fraction (ultra-high-sulphur protein) as would be expected from the results of dietary supplementation experiments. Low-crimp wools do not appear to contain this protein fraction and in this respect they may differ from high-crimp wools.

Measurement of Sliver Drafting Forces

A staple draftometer is described using a "Hall Effect" wattmeter as the transducer for measuring dynamic forces in staple slivers during drafting. The procedure for calibration and use of the instrument is also given. A novel feature of the apparatus is the use of a decade resistance box to calibrate the desired full-scale force range. Drafting force was a hyperbolic function of draft ratio (beyond 1.5× draft), and the relationship between the two variables can be expressed in terms of a constant as shown by the following equation: (Drafting Force) X (Draft Ratio) = K Thus the drafting force curve in terms of draft ratios can be defined by a single numher. An increase in crimp frequency (0-15 crimps per inch range) gave an exponential increase in sliver drafting force. Addition of luhricants such as Ucon® or silicone oils to clean T-54 Dacron® polyester fiber slivers produced a significant reduction in drafting force, most of which occurred during the addition of the first 0.1% lubricant. The absolute drafting force is governed by specific properties of the lubricant.

A Generalized Model for Crimp Analysis of Multi-Component Fibers

The present status of bicomponent fiber crimp frequency analysis is briefly reviewed. In order to develop a generalized model for the prediction of radius of curvature (or crimp frequency) of multi- (or bi-) component fiber, with an arbitrary shape of the cross-section and interfacial curves, the background of compound bars in the literature of classical theory of elasticity is also reviewed. Employing the semi-inverse method of St. Venant, the radius of curvature in the generalized case is derived through the use of the principle of minimum potential energy (see Appendix A). Both the limitations and the usefulness of the results are discussed.

13—SOME OBSERVATIONS ON THE OBJECTIVE CHARACTERISTICS OF CLASSED WOOL CLIPS PART I: DISTRICT ANALYSIS

Some relations between fibre diameter, quality number, and staple-crimp frequency among classers' lines are reported. There is a strong over-all relation between quality number and crimp frequency. The within-clip relations do vary, apparently as a result of a tendency among appraisers of superfine wools to allot classed lines from the same clip into different quality-number categories on the basis of small differences in staple-crimp frequency. This effect disappears when data from different clips are pooled. The relation between fibre diameter and quality number is also strong, but the slope of the regression line of fibre diameter on quality number varies markedly between districts, even when individual clip data are pooled. These two relations, taken together, reveal that the classification of fleeces on the basis of the quality-number system is not particularly effective in producing lots that differ significantly in fibre diameter.

Selection for crimp frequency in the wool of Merino sheep. 2. Efficiency of conversion of food to wool

Two experiments were conducted in which the efficiency of wool production of Merino sheep selected for increased (Crimps Plus) and decreased (Crimps Minus) crimp frequency, and a randomly selected control flock, was examined under pen feeding conditions. Ewes for the second experiment were chosen from the same genetic flocks as those used in the first experiment, after a further 1.8 generations (six years) of selection. In the first experiment, in which four levels of roughage diet were offered to ewes from each of the genetic groups, Crimps Minus ewes consistently produced more wool and with a greater efficiency than Random ewes, which were superior in these two characters relative to Crimps Plus ewes. Similar results were obtained in the second experiment, in which ewes were fed to maintain liveweight. Wool production and efficiency of Fleece Plus ewes were greater than those of Crimps Minus ewes indicating a higher genetic correlation between efficiency and fleece weight than between efficiency and crimp frequency.

Selection for clean fleece weight in Merino sheep. II.* Correlated responses to selection

Correlated responses to selection for high and low clean fleece weight (W) in the Peppin Merino (Fleece plus and Fleece minus flocks respectively) are presented together with estimates of realized genetic correlations where appropriate. There were strong positive correlations between W and greasy fleece weight and between W and clean scoured yield, and a strong negative correlation between Wand crimp frequency. There was no consistent association between W and body weight. Selection for W caused little change in wool colour, a slight improvement in wool character, and an improvement in wool handle in the rams, but not in the ewes. There was an increase in face cover score and a decrease in birthcoat score in the Fleece minus flock, but there was no change in either trait in the Fleece plus flock. Possible reasons for these asymmetries are discussed. Most of the response in W in the Fleece plus flock arose through increases in fibre density, fibre diameter and staple length. Staple length was the major component associated with response in W in the Fleece minus flock. Decreases also occurred in fibre density and wrinkle score but there was no change in fibre diameter. Continued response in W in the Fleece minus flock was through staple length and, to a lesser extent, wrinkle score. The response in fibre density in both flocks arose through change in the ratio of secondary to primary fibres. Two-year-old and lifetime reproductive performances are reported for the two selection flocks. The Fleece minus 2-year-old ewes weaned significantly more lambs than their Fleece plus counterparts over the period studied. The lifetime reproductive performance of ewes was similar in both flocks, although there were significantly more multiple births in the Fleece plus flock. An examination of the divergence between the two flocks revealed no significant time trends. The asymmetrical pattern of response in W in these flocks is discussed in the light of the present data. __________________ *Part I, Aust. J. Agric. Res., 25: 643 (1974).

Three-Dimensional Geometry of Crimp

Geometric torsion and curvature accurately describe three-dimensional forms of crimp. The usual parameters of crimp frequency and indices of amplitude or extensibility for idealized planar or helical crimp forms are expressible by specific relationships of geometric torsion and curvature. The more common, nonideal crimp forms are characterized by distribu tion statistics of these two fundamental parameters along the fiber. Mathematical techniques and analytical expressions were developed for describing crimp this way with data from an automatic crimp-measuring instrument and use of a digital computer. Examples are given from measurements made on several commercial man-made and natural fibers.

Phenotypic and genetic associations between production characters and blood characters in sheep. Erythrocyte potassium levels and haemoglobin types in Peppin Merinos genetically different for clean fleece weight and crimp frequency

SummaryRed blood cell electrolyte levels and haemoglobin types have been determined in flocks of Peppin Merino sheep genetically different for clean fleece weight and crimp frequency. The flocks selected for high clean fleece weight or low crimp frequency had significantly higher mean erythrocyte potassium levels than did those flocks selected for low clean fleece weight or high crimp frequency, this difference was apparent in both haemoglobin AB and BB types. Erythrocyte potassium concentration was not correlated with either clean fleece weight or crimp frequency within flocks. The high clean fleece weight flock had a significantly higher gene frequency for high potassium than did the low clean fleece weight flock, while the high crimp frequency flock had a lower haemoglobin B gene frequency than the low crimp frequency flock.