PROD-200 An Inherently Variable Product
Wool Production focuses on the characteristics of Merino wool which influence its value, such as fleece weight, average fibre diameter, staple strength, staple length, colour, vegetable matter and style. The impact of genetics, nutrition, environment, physiology and management on these wool characteristics is examined. The interactions between these factors is explored in a range of environments, providing a systems approach to wool production in each and an understanding of the constraints to wool production at a national level, thus allowing the identification and evaluation of options available to the commercial woolgrower for improving productivity and the value of their clip.
The components and variability of the characteristics of Merino wool influence its value, such as fleece weight, average fibre diameter, staple strength, staple length, colour, vegetable matter and style. The relative importance of these raw wool characteristics to fleece value is also considered in this theme.
PROD-200-050 Fleece weight, diameter, length and yield
Aspects of greasy and clean fleece weights and components such as body weight, follicle density, fibre diameter and fibre length that may influence fleece weight are described. Sources of variation of fibre diameter and fibre length, and non-fibre components of the fleece are outlined and their impact on final wool price demonstrated.
PROD-200-050-025 Fleece weight: greasy vs clean
This module defines greasy and clean fleece weights, as well as the measurement of washing yield used in flock testing. The phenotypic correlations between fleece weight, yield and the non-fibre components of the fleece are also given.
PROD-200-050-050 The components of clean fleece weight
This module defines clean fleece weight as a composite trait, reflecting the contributions of body weight, skin folds, fibre density, staple length and fibre diameter. The way in which these components combine to influence clean fleece weight is shown for two scenarios, one demonstrating the response to an increase in nutritional level and one showing the response to selection for clean fleece weight.
PROD-100-050-100 Within-fleece gradients in the components of clean fleece weight
This module considers the gradients within the fleece (or across the body) in wool production per unit area of skin and the component traits of fibre diameter, staple length and follicle density. The appropriateness of the mid-side sample for estimating the fleece (or sheep) average is discussed.
PROD-100-050-150 Non-genetic handicaps in the components of clean fleece weight
This module describes the extent of non-genetic handicaps such as age of dam, birth-rearing status and age on hogget performance for clean fleece weight and its components. The potential for bias at selection is discussed. The magnitude of annual variation in these traits is also shown.
PROD-100-050-200 Time trends: fleece weight and yield
This module displays the trends over time in the national average wool cut per head (from 1891 to 1992) and yield (from 1950 to 1992).
PROD-100-050-250 Premiums and discounts for fibre diameter and staple length
This module demonstrates the premiums and discounts for fibre diameter and staple length as realised at auction.
PROD-100-050-300 Sources of variation in fibre diameter and fibre length
This module partitions within-mob variation in fibre diameter and fibre length according to: variation between sheep; variation between sites within a fleece; variation between staples within a site; variation between fibres within a staple. It demonstrates that there is more variation in diameter and length within a single staple than there is between sheep within a mob.
PROD-100-050-350 Sources of variation in the non-fibre components of the fleece
This module examines sources of variation in the non-fibre components of the fleece: wax, suint, vegetable matter and dirt. Within-fleece gradients in these traits are outlined, including the appropriateness of the mid-side for estimating fleece averages.
PROD-200-100 Staple Strength
Various aspects of staple strength are examined in this topic. These include the definition of the measurement of staple strength, the role that fibre diameter plays in determining staple strength, fibre length variation within a staple and how this can influence staple strength, the potential role of intrinsic fibre strength, and premiums and discounts for staple strength.
PROD-200-100-050 Defining the measurement of staple strength
This module provides a basic definition of the measurement of staple strength and position of break.
PROD-200-100-100 Premiums and discounts for staple strength
This module demonstrates the nature of premiums and discounts for measured staple strength at auction. The dependency of the premiums and discounts on fibre diameter is shown, as is the non-linear relationship between measured staple strength and clean price.
PROD-200-100-150 Sources of variation in staple strength
This module looks at sources of variation in staple strength. Gradients within the fleece are discussed as is the use of the mid-side for estimating the fleece average.
PROD-200-100-200 Overview of potential determinants of staple strength
This module provides a theoretical framework within which to view the various determinants of staple strength. It introduces the notions of localised and generalised fibre weakness.
PROD-200-100-250 Staple strength: the influence of fibre diameter and diameter variation
This module looks at the relationship between average fibre diameter and staple strength, and diameter variation and staple strength. The greater contribution of along-fibre diameter variation for low strength wool is discussed.
PROD-200-100-300 Fibre diameter profiles
This module looks at fibre diameter profiles, this being the pattern of change in fibre diameter along the length of the staple. Specific parameters of the profile are identified. Differences between sheep within a mob and differences between genetic groups within a flock are shown, suggesting a degree of genetic control of the diameter response to environmental changes.
PROD-200-100-350 Staple strength: the potential role of initial diameter, rate of change in diameter and L/D ratio
This module introduces the concepts of initial fibre diameter, rate of change in fibre diameter and the length/diameter ratio (L/D). Attention is given to how these measurements may relate to staple strength.
PROD-200-100-400 Staple strength: the potential role of length variation
This module looks at fibre length variation within a staple and how this can influence staple strength. The major context of this is the presence of shed fibres within the staple.
PROD-200-100-450 Staple strength: the potential role of intrinsic fibre strength
This module provides a basic introduction to intrinsic fibre strength. Brief mention is made of how intrinsic strength may influence measured staple strength.
PROD-200-150 Fibre Diameter Variation, Style and Handle
Fibre diameter variation is covered in more detail in this topic, with aspects such as within-fleece gradients, micron blow-out and coarse edge defined and examined. The concept of raw wool style is addressed and the influence of various raw wool characteristics on wool style is explained. The role of fibre curvature on style and handle is also examined.
PROD-200-150-050 Fibre diameter variation defined
This module examines the parameters derived from the measured distribution of fibre diameter. It defines average diameter, standard deviation of diameter, coefficient of variation of diameter and coarse edge. The relationship between average diameter and diameter variation is shown.
PROD-200-150-100 Within-fleece gradients in diameter variation
This module examines within-fleece gradients for diameter variation, measured as either the standard deviation of diameter in the wool sample or the along-staple variation in diameter. Non-genetic sources of variation in these measurements are also discussed. The influence of skin folds on diameter variation is mentioned.
PROD-200-150-150 Micron blow-out
This module introduces the concept of micron blow-out. It also examines the industry perception that high diameter variation is an indicator of propensity for blow-out.
PROD-200-150-200 Coarse edge defined
This module defines the coarse edge or prickle factor and shows how this trait relates to average fibre diameter.
PROD-200-150-250 Associations involving fibre curvature
This module presents phenotypic correlations involving mean fibre curvature and curvature variation.
PROD-200-150-300 Style and the Australian wool clip
This module introduces the concept of raw wool style and provides a breakdown of state and national clips into the various style grades. It reflects the influence of environmental factors on style, suggesting that style is a function of the interaction between fleece and environment.
PROD-200-150-350 Premiums and discounts for style
This module presents the price differentials for style grade at auction and the dependency of these differentials on fibre diameter.
PROD-200-150-400 The components of style
This module examines style as a composite trait, reflecting crimp frequency, crimp definition, tip and staple structure, dust penetration, weathering and greasy colour. The contribution of each component trait to differences in style grade are discussed.
PROD-200-150-450 Sources of variation in style traits
This module presents within- and between- fleece variation in style traits.
PROD-200-150-500 The influence of sheep coats on wool style
This module looks briefly at the use of sheep coats to improve wool style by presenting a barrier for the entry of dust and VM into the fleece.  The economic considerations of using coats for this purpose is discussed
PROD-200-150-550 Associations between style traits and fibre diameter variation
This module presents the phenotypic correlations between diameter variation and a number of style traits ( crimp definition, staple thickness, staple structure, dust penetration and greasy colour).
PROD-200-150-600 Handle
This module introduces the concept of handle, this being the tactile properties of wool fibres. The role of fibre diameter and fibre curvature or crimp in determining handle is discussed. The relationship between diameter and curvature (crimp) is also shown.
PROD-200-200 Wool Colour and Fleece Rot
Wool colour, its measurement, the chemical reactions likely to occur when discolouration results, fleece factors which differentiate susceptible and resistant types in terms of wool discolouration and the association between wool colour and fleece rot are the subjects of this topic.
PROD-200-200-050 Assessed and measured wool colour
This module addresses subjectively-assessed greasy wool colour and objectively-measured clean colour, showing the poor relationship that exists between them. The level of discolouration present within the national clip is shown. The discounts imposed for discolouration in wool sold at auction are indicated, showing that greater discounts are imposed for discolouration in finer wool.
PROD-200-200-100 The chemical reactions involved in wool discolouration
This module summarises the chemical reactions likely to occur when wool discolouration results. The importance of moisture, heat, fleece chemistry and microbial activity is highlighted.
PROD-200-200-150 Resistance to wool discolouration
This module addresses some of the fleece factors which differentiate susceptible and resistant types in terms of wool discolouration. This helps to explain in part the difference between the Merino strains in the relative brightness and whiteness of the wool produced.
PROD-200-200-200 Incubated colour test
This module presents the incubated colour test as a means of identifying susceptible genotypes when environmental factors are not conducive to discolouration. The relationships between determinants of discolouration and the colour forming during incubation are shown.
PROD-200-200-250 Wool colour and fleece rot
This module examines the association between wool discolouration and the development of fleece rot, suggesting that wool colour may provide an indirect criteria for identifying individuals susceptible to fleece rot.
PROD-200-200-300 Susceptibility to fleece rot
This module addresses those factors influencing susceptibility of the sheep to fleece rot. Strain and bloodline differences in fleece rot susceptibility are shown.
PROD-200-250 Dark Fibre Contamination
Dark fibre contamination in the Merino industry is addressed in this topic, with a focus on sheep-derived sources of this contamination.
PROD-200-250-050 Dark fibre contamination
This module examines dark fibre contamination in the Merino industry, focusing on the sheep-derived sources of this contamination. It provides detailed discussion on the role of pigmented skin spots and isolated pigmented fibres in contributing to dark fibre contamination, and discusses potential genetic strategies for reducing isolated pigmented fibres. It also looks at urine stain, given that it is the major source of dark fibre contamination, and identifies the major management and clip preparation factors affecting dark fibre contamination associated with urine stain.
PROD-200-300 Vegetable matter contamination
This module introduces vegetable matter (VM) contamination. It defines the problem in terms of major contaminating species, price discounts for wool sold at auction, and differences between states and locations within states in VM amount and type. An AWTA Ltd publication, “Vegetable Matter in Australian Wool“, is available with this module.
PROD-200-300-050 Vegetable matter contamination
This module introduces vegetable matter (VM) contamination. It defines the problem in terms of major contaminating species, price discounts for wool sold at auction, and differences between states and locations within states in VM amount and type.
PROD-200-300-100 Shearing time and vegetable matter contamination
This module looks at the importance of shearing time in determining the amount and type of vegetable fault present in the fleece. A distinction is made between annual and perennial pasture systems, given the differences between the two in pasture dynamics and seed set. The influence of wool length on seed penetration of the skin is also included.
PROD-200-300-150 Stocking rate effects on vegetable matter
This module gives an example of how stocking rate can influence vegetable matter (VM) contamination by modifying the species composition of the pasture, and thus also the amount and type of vegetable fault present in the fleece.
PROD-200-300-200 Using sheep coats to control vegetable matter contamination
This module investigates the use of sheep coats to reduce the entry of vegetable matter (VM) into the fleece. The value of this strategy depends on the pasture species present, and the improvements in wool value arising from VM reduction, this being dependent on fibre diameter.
PROD-200-300-250 The potential for developing less problematic varieties of pasture species
This module provides an example of the opportunities that exist for developing less problematic varieties of valuable pasture species. The example looks at spineless varieties of barrel medic.